97ff0102cd
The whole point of using a table is not only that comparisons like (c >= 'a' && c <= 'z') can be eliminated; but also that conditional branches (the "ands" and "ifs") should be eliminated as well. The existing code, however, uses separate branches to check e.g. for the end of string; to check for an error; and to check for the (num6b < 61) common case. With this change, the table is restructured so that the common case will be handled with only a single instruction.
1139 lines
26 KiB
C
1139 lines
26 KiB
C
/*
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* set.c - base62, golomb and set-string routines
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*
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* Copyright (C) 2010 Alexey Tourbin <at@altlinux.org>
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*
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* License: GPLv2+ or LGPL, see RPM COPYING
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*/
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#ifdef SELF_TEST
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#undef NDEBUG
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#include <stdio.h>
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#endif
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#include <string.h>
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#include <stdlib.h>
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#include <assert.h>
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/*
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* Base62 routines - encode bits with alnum characters.
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*
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* This is a base64-based base62 implementation. Values 0..61 are encoded
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* with '0'..'9', 'a'..'z', and 'A'..'Z'. However, 'Z' is special: it will
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* also encode 62 and 63. To achieve this, 'Z' will occupy two high bits in
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* the next character. Thus 'Z' can be interpreted as an escape character
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* (which indicates that the next character must be handled specially).
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* Note that setting high bits to "00", "01" or "10" cannot contribute
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* to another 'Z' (which would require high bits set to "11"). This is
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* how multiple escapes can be effectively avoided.
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*/
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// Estimate base62 buffer size required to encode a given number of bits.
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static inline
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int encode_base62_size(int bitc)
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{
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// Four bits can make a character; the remaining bits can make
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// a character, too. And the string should be null-terminated.
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return (bitc >> 2) + 2;
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}
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// Main base62 encoding routine: pack bitv into base62 string.
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static
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int encode_base62(int bitc, const char *bitv, char *base62)
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{
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char *base62_start = base62;
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void put_digit(int c)
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{
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assert(c >= 0 && c <= 61);
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if (c < 10)
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*base62++ = c + '0';
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else if (c < 36)
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*base62++ = c - 10 + 'a';
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else if (c < 62)
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*base62++ = c - 36 + 'A';
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}
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int bits2 = 0; // number of high bits set
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int bits6 = 0; // number of regular bits set
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int num6b = 0; // pending 6-bit number
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while (bitc-- > 0) {
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num6b |= (*bitv++ << bits6++);
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if (bits6 + bits2 < 6)
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continue;
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switch (num6b) {
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case 61:
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// escape
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put_digit(61);
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// extra "00...." high bits (in the next character)
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bits2 = 2;
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bits6 = 0;
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num6b = 0;
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break;
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case 62:
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put_digit(61);
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// extra "01...." high bits
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bits2 = 2;
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bits6 = 0;
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num6b = 16;
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break;
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case 63:
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put_digit(61);
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// extra "10...." high bits
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bits2 = 2;
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bits6 = 0;
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num6b = 32;
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break;
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default:
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assert(num6b < 61);
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put_digit(num6b);
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bits2 = 0;
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bits6 = 0;
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num6b = 0;
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break;
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}
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}
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if (bits6 + bits2) {
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assert(num6b < 61);
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put_digit(num6b);
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}
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*base62 = '\0';
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return base62 - base62_start;
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}
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// Estimate how many bits will result from decoding a base62 string.
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static inline
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int decode_base62_size(const char *base62)
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{
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int len = strlen(base62);
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// Each character will fill at most 6 bits.
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return (len << 2) + (len << 1);
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}
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// This table maps alnum characters to their numeric values.
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static
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const int char_to_num[256] = {
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[0 ... 255] = 0xee,
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[0] = 0xff,
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#define C1(c, b) [c] = c - b
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#define C2(c, b) C1(c, b), C1(c + 1, b)
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#define C5(c, b) C1(c, b), C2(c + 1, b), C2(c + 3, b)
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#define C10(c, b) C5(c, b), C5(c + 5, b)
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C10('0', '0'),
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#define C26(c, b) C1(c, b), C5(c + 1, b), C10(c + 6, b), C10(c + 16, b)
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C26('a', 'a' + 10),
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C26('A', 'A' + 36),
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};
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// Main base62 decoding routine: unpack base62 string into bitmap.
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static
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int decode_base62(const char *base62, char *bitv)
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{
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char *bitv_start = bitv;
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inline
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void put6bits(int c)
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{
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*bitv++ = (c >> 0) & 1;
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*bitv++ = (c >> 1) & 1;
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*bitv++ = (c >> 2) & 1;
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*bitv++ = (c >> 3) & 1;
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*bitv++ = (c >> 4) & 1;
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*bitv++ = (c >> 5) & 1;
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}
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inline
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void put4bits(int c)
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{
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*bitv++ = (c >> 0) & 1;
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*bitv++ = (c >> 1) & 1;
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*bitv++ = (c >> 2) & 1;
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*bitv++ = (c >> 3) & 1;
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}
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// ----8<----
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while (1) {
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int c = (unsigned char) *base62++;
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int num6b = char_to_num[c];
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while (num6b < 61) {
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put6bits(num6b);
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c = (unsigned char) *base62++;
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num6b = char_to_num[c];
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}
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if (num6b == 0xff)
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break;
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if (num6b == 0xee)
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return -1;
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assert(num6b == 61);
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c = (unsigned char) *base62++;
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int num4b = char_to_num[c];
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if (num4b == 0xff)
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return -2;
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if (num4b == 0xee)
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return -3;
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switch (num4b & (16 + 32)) {
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case 0:
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break;
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case 16:
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num6b = 62;
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num4b &= ~16;
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break;
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case 32:
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num6b = 63;
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num4b &= ~32;
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break;
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default:
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return -4;
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}
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put6bits(num6b);
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put4bits(num4b);
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}
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// ---->8----
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return bitv - bitv_start;
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}
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#ifdef SELF_TEST
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static
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void test_base62()
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{
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const char rnd_bitv[] = {
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1, 0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 0, 1, 0, 0, 1,
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1, 1, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 1,
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0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0,
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0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0,
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// trigger some 'Z'
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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};
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const int rnd_bitc = sizeof rnd_bitv;
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// encode
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char base62[encode_base62_size(rnd_bitc)];
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int len = encode_base62(rnd_bitc, rnd_bitv, base62);
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assert(len > 0);
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assert(len == (int)strlen(base62));
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fprintf(stderr, "len=%d base62=%s\n", len, base62);
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// The length cannot be shorter than 6 bits per symbol.
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assert(len >= rnd_bitc / 6);
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// Neither too long: each second character must fill at least 4 bits.
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assert(len <= rnd_bitc / 2 / 4 + rnd_bitc / 2 / 6 + 1);
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// decode
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char bitv[decode_base62_size(base62)];
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int bitc = decode_base62(base62, bitv);
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fprintf(stderr, "rnd_bitc=%d bitc=%d\n", rnd_bitc, bitc);
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assert(bitc >= rnd_bitc);
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// Decoded bits must match.
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int i;
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for (i = 0; i < rnd_bitc; i++)
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assert(rnd_bitv[i] == bitv[i]);
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// The remaining bits must be zero bits.
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for (i = rnd_bitc; i < bitc; i++)
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assert(bitv[i] == 0);
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fprintf(stderr, "%s: base62 test OK\n", __FILE__);
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}
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#endif
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/*
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* Golomb-Rice routines - compress integer values into bits.
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*
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* The idea is as follows. Input values are assumed to be small integers.
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* Each value is split into two parts: an integer resulting from its higher
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* bits and an integer resulting from its lower bits (with the number of lower
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* bits specified by the Mshift parameter). The frist integer is then stored
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* in unary coding (which is a variable-length sequence of '0' followed by a
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* terminating '1'); the second part is stored in normal binary coding (using
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* Mshift bits).
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*
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* The method is justified by the fact that, since most of the values are
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* small, their first parts will be short (typically 1..3 bits). In particular,
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* the method is known to be optimal for uniformly distributed hash values,
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* after the values are sorted and delta-encoded. See e.g.
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* Putze, F.; Sanders, P.; Singler, J. (2007),
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* "Cache-, Hash- and Space-Efficient Bloom Filters",
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* http://algo2.iti.uni-karlsruhe.de/singler/publications/cacheefficientbloomfilters-wea2007.pdf
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*/
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// Calculate Mshift paramter for encoding.
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static
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int encode_golomb_Mshift(int c, int bpp)
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{
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int log2i(int n)
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{
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int m = 0;
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while (n >>= 1)
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m++;
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return m;
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}
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// XXX Slightly better Mshift estimations are probably possible.
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// Recheck "Compression and coding algorithms" by Moffat & Turpin.
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int Mshift = bpp - log2i(c) - 1;
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// Adjust out-of-range values.
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if (Mshift < 7)
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Mshift = 7;
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if (Mshift > 31)
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Mshift = 31;
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assert(Mshift < bpp);
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return Mshift;
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}
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// Estimate how many bits can be filled up.
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static inline
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int encode_golomb_size(int c, int Mshift)
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{
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// XXX No precise estimation. However, we do not expect unary-encoded bits
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// to take more than binary-encoded Mshift bits.
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return (Mshift << 1) * c + 16;
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}
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// Main golomb encoding routine: package integers into bits.
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static
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int encode_golomb(int c, const unsigned *v, int Mshift, char *bitv)
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{
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char *bitv_start = bitv;
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const unsigned mask = (1 << Mshift) - 1;
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while (c > 0) {
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c--;
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unsigned v0 = *v++;
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int i;
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// first part: variable-length sequence
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unsigned q = v0 >> Mshift;
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for (i = 0; i < (int)q; i++)
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*bitv++ = 0;
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*bitv++ = 1;
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// second part: lower Mshift bits
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unsigned r = v0 & mask;
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for (i = 0; i < Mshift; i++)
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*bitv++ = (r >> i) & 1;
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}
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return bitv - bitv_start;
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}
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// Estimate how many values will emerge.
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static inline
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int decode_golomb_size(int bitc, int Mshift)
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{
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// Each (Mshift + 1) bits can make a value.
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// The remaining bits cannot make a value, though.
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return bitc / (Mshift + 1);
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}
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// Main golomb decoding routine: unpackage bits into values.
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static
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int decode_golomb(int bitc, const char *bitv, int Mshift, unsigned *v)
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{
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unsigned *v_start = v;
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// next value
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while (bitc > 0) {
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// first part
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unsigned q = 0;
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char bit = 0;
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while (bitc > 0) {
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bitc--;
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bit = *bitv++;
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if (bit == 0)
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q++;
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else
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break;
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}
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// trailing zero bits in the input are okay
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if (bitc == 0 && bit == 0)
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break;
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// otherwise, incomplete value is not okay
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if (bitc < Mshift)
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return -10;
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// second part
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unsigned r = 0;
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int i;
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for (i = 0; i < Mshift; i++) {
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bitc--;
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if (*bitv++)
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r |= (1 << i);
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}
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// the value
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*v++ = (q << Mshift) | r;
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}
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return v - v_start;
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}
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// Combined base62+golomb decoding routine, no need for bitv[].
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static
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int decode_base62_golomb(const char *base62, int Mshift, unsigned *v)
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{
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unsigned *v_start = v;
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unsigned q = 0;
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unsigned r = 0;
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int rfill = 0;
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enum { ST_VLEN, ST_MBITS } state = ST_VLEN;
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inline
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void putNbits(unsigned c, int n)
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{
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if (state == ST_VLEN)
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goto vlen;
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r |= (c << rfill);
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rfill += n;
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int left = rfill - Mshift;
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if (left < 0)
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return;
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r &= (1 << Mshift) - 1;
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*v++ = (q << Mshift) | r;
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q = 0;
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state = ST_VLEN;
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if (left == 0)
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return;
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c >>= n - left;
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n = left;
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vlen:
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do {
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n--;
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if (c & 1) {
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r = (c >> 1);
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rfill = n;
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state = ST_MBITS;
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return;
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}
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q++;
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c >>= 1;
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}
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while (n > 0);
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}
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inline
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void put6bits(unsigned c)
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{
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putNbits(c, 6);
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}
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inline
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void put4bits(unsigned c)
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{
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putNbits(c, 4);
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}
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// ----8<----
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while (1) {
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int c = (unsigned char) *base62++;
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int num6b = char_to_num[c];
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while (num6b < 61) {
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put6bits(num6b);
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c = (unsigned char) *base62++;
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num6b = char_to_num[c];
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}
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if (num6b == 0xff)
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break;
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if (num6b == 0xee)
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return -1;
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assert(num6b == 61);
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c = (unsigned char) *base62++;
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int num4b = char_to_num[c];
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if (num4b == 0xff)
|
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return -2;
|
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if (num4b == 0xee)
|
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return -3;
|
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switch (num4b & (16 + 32)) {
|
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case 0:
|
|
break;
|
|
case 16:
|
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num6b = 62;
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num4b &= ~16;
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break;
|
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case 32:
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num6b = 63;
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num4b &= ~32;
|
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break;
|
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default:
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return -4;
|
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}
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put6bits(num6b);
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put4bits(num4b);
|
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}
|
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// ---->8----
|
|
if (state != ST_VLEN)
|
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return -10;
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return v - v_start;
|
|
}
|
|
|
|
#ifdef SELF_TEST
|
|
static
|
|
void test_golomb()
|
|
{
|
|
const unsigned rnd_v[] = {
|
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// do re mi fa sol la si
|
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1, 2, 3, 4, 5, 6, 7,
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// koshka sela na taksi
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|
7, 6, 5, 4, 3, 2, 1,
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};
|
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const int rnd_c = sizeof rnd_v / sizeof *rnd_v;
|
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int bpp = 10;
|
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int Mshift = encode_golomb_Mshift(rnd_c, bpp);
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fprintf(stderr, "rnd_c=%d bpp=%d Mshift=%d\n", rnd_c, bpp, Mshift);
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assert(Mshift > 0);
|
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assert(Mshift < bpp);
|
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// encode
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int alloc_bitc = encode_golomb_size(rnd_c, Mshift);
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assert(alloc_bitc > rnd_c);
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char bitv[alloc_bitc];
|
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int bitc = encode_golomb(rnd_c, rnd_v, Mshift, bitv);
|
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fprintf(stderr, "alloc_bitc=%d bitc=%d\n", alloc_bitc, bitc);
|
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assert(bitc > rnd_c);
|
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assert(bitc <= alloc_bitc);
|
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// decode
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int alloc_c = decode_golomb_size(bitc, Mshift);
|
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assert(alloc_c >= rnd_c);
|
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unsigned v[alloc_c];
|
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int c = decode_golomb(bitc, bitv, Mshift, v);
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fprintf(stderr, "rnd_c=%d alloc_c=%d c=%d\n", rnd_c, alloc_c, c);
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assert(alloc_c >= c);
|
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// Decoded values must match.
|
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assert(rnd_c == c);
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int i;
|
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for (i = 0; i < c; i++)
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assert(rnd_v[i] == v[i]);
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// At the end of the day, did it save your money?
|
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int golomb_bpp = bitc / c;
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fprintf(stderr, "bpp=%d golomb_bpp=%d\n", bpp, golomb_bpp);
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assert(golomb_bpp < bpp);
|
|
fprintf(stderr, "%s: golomb test OK\n", __FILE__);
|
|
}
|
|
|
|
static
|
|
void test_base62_golomb()
|
|
{
|
|
// test combinded base62+golomb decoder
|
|
const char str[] = "set:hdf7q2P5VZwtLGr9TKxhrEM1";
|
|
const char *base62 = str + 4 + 2;
|
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int Mshift = 10;
|
|
char bitv[256];
|
|
int bitc = decode_base62(base62, bitv);
|
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assert(bitc > 0);
|
|
unsigned v1[32], v2[32];
|
|
int c1 = decode_golomb(bitc, bitv, Mshift, v1);
|
|
assert(c1 > 0);
|
|
int c2 = decode_base62_golomb(base62, Mshift, v2);
|
|
assert(c2 > 0);
|
|
assert(c1 == c2);
|
|
int i;
|
|
for (i = 0; i < c1; i++)
|
|
assert(v1[i] == v2[i]);
|
|
fprintf(stderr, "%s: base62_golomb test OK\n", __FILE__);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Delta encoding routines - replace an increasing sequence of integer values
|
|
* by the sequence of their differences.
|
|
*/
|
|
|
|
static
|
|
void encode_delta(int c, unsigned *v)
|
|
{
|
|
assert(c > 0);
|
|
unsigned *v_end = v + c;
|
|
unsigned v0 = *v++;
|
|
while (v < v_end) {
|
|
*v -= v0;
|
|
v0 += *v++;
|
|
}
|
|
}
|
|
|
|
static
|
|
void decode_delta(int c, unsigned *v)
|
|
{
|
|
assert(c > 0);
|
|
unsigned *v_end = v + c;
|
|
unsigned v0 = *v++;
|
|
while (v < v_end) {
|
|
*v += v0;
|
|
v0 = *v++;
|
|
}
|
|
}
|
|
|
|
#ifdef SELF_TEST
|
|
static
|
|
void test_delta()
|
|
{
|
|
unsigned v[] = {
|
|
1, 3, 7, 0
|
|
};
|
|
int c = 3;
|
|
encode_delta(c, v);
|
|
assert(v[0] == 1);
|
|
assert(v[1] == 2);
|
|
assert(v[2] == 4);
|
|
assert(v[3] == 0);
|
|
decode_delta(c, v);
|
|
assert(v[0] == 1);
|
|
assert(v[1] == 3);
|
|
assert(v[2] == 7);
|
|
assert(v[3] == 0);
|
|
fprintf(stderr, "%s: delta test OK\n", __FILE__);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Auxiliary routines.
|
|
*/
|
|
|
|
static
|
|
void maskv(int c, unsigned *v, unsigned mask)
|
|
{
|
|
unsigned *v_end = v + c;
|
|
while (v < v_end)
|
|
*v++ &= mask;
|
|
}
|
|
|
|
static
|
|
void sortv(int c, unsigned *v)
|
|
{
|
|
int cmp(const void *arg1, const void *arg2)
|
|
{
|
|
unsigned v1 = *(unsigned *) arg1;
|
|
unsigned v2 = *(unsigned *) arg2;
|
|
if (v1 > v2)
|
|
return 1;
|
|
if (v1 < v2)
|
|
return -1;
|
|
return 0;
|
|
}
|
|
qsort(v, c, sizeof *v, cmp);
|
|
}
|
|
|
|
static
|
|
int uniqv(int c, unsigned *v)
|
|
{
|
|
int i, j;
|
|
for (i = 0, j = 0; i < c; i++) {
|
|
while (i + 1 < c && v[i] == v[i+1])
|
|
i++;
|
|
v[j++] = v[i];
|
|
}
|
|
assert(j <= c);
|
|
return j;
|
|
}
|
|
|
|
#ifdef SELF_TEST
|
|
static
|
|
void test_aux()
|
|
{
|
|
unsigned v[] = { 2, 3, 1, 2, 7, 6, 5 };
|
|
int c = sizeof v / sizeof *v;
|
|
maskv(c, v, 4 - 1);
|
|
sortv(c, v);
|
|
c = uniqv(c, v);
|
|
assert(c == 3);
|
|
assert(v[0] == 1);
|
|
assert(v[1] == 2);
|
|
assert(v[2] == 3);
|
|
fprintf(stderr, "%s: aux test OK\n", __FILE__);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Higher-level set-string routines - serialize integers into a set-string.
|
|
*
|
|
* A set-string looks like this: "set:bMxyz..."
|
|
*
|
|
* The "set:" prefix marks set-versions in rpm (to distinguish them between
|
|
* regular rpm versions). It is assumed to be stripped here.
|
|
*
|
|
* The next two characters (denoted 'b' and 'M') encode two small integers
|
|
* in the range 7..32 using 'a'..'z'. The first character encodes bpp.
|
|
* Valid bpp range is 10..32. The second character encodes Mshift. Valid
|
|
* Mshift range is 7..31. Also, valid Mshift must be less than bpp.
|
|
*
|
|
* The rest ("xyz...") is a variable-length sequence of alnum characters.
|
|
* It encodes a (sorted) set of (non-negative) integer values, as follows:
|
|
* integers are delta-encoded, golomb-compressed and base62-serialized.
|
|
*/
|
|
|
|
static
|
|
int encode_set_size(int c, int bpp)
|
|
{
|
|
int Mshift = encode_golomb_Mshift(c, bpp);
|
|
int bitc = encode_golomb_size(c, Mshift);
|
|
// two leading characters are special
|
|
return 2 + encode_base62_size(bitc);
|
|
}
|
|
|
|
static
|
|
int encode_set(int c, unsigned *v, int bpp, char *base62)
|
|
{
|
|
// XXX v is non-const due to encode_delta
|
|
int Mshift = encode_golomb_Mshift(c, bpp);
|
|
int bitc = encode_golomb_size(c, Mshift);
|
|
char bitv[bitc];
|
|
// bpp
|
|
if (bpp < 10 || bpp > 32)
|
|
return -1;
|
|
*base62++ = bpp - 7 + 'a';
|
|
// golomb parameter
|
|
if (Mshift < 7 || Mshift > 31)
|
|
return -2;
|
|
*base62++ = Mshift - 7 + 'a';
|
|
// delta
|
|
encode_delta(c, v);
|
|
// golomb
|
|
bitc = encode_golomb(c, v, Mshift, bitv);
|
|
#ifdef SELF_TEST
|
|
decode_delta(c, v);
|
|
#endif
|
|
if (bitc < 0)
|
|
return -3;
|
|
// base62
|
|
int len = encode_base62(bitc, bitv, base62);
|
|
if (len < 0)
|
|
return -4;
|
|
return 2 + len;
|
|
}
|
|
|
|
static
|
|
int decode_set_init(const char *str, int *pbpp, int *pMshift)
|
|
{
|
|
// 7..32 values encoded with 'a'..'z'
|
|
int bpp = *str++ + 7 - 'a';
|
|
if (bpp < 10 || bpp > 32)
|
|
return -1;
|
|
// golomb parameter
|
|
int Mshift = *str++ + 7 - 'a';
|
|
if (Mshift < 7 || Mshift > 31)
|
|
return -2;
|
|
if (Mshift >= bpp)
|
|
return -3;
|
|
// no empty sets for now
|
|
if (*str == '\0')
|
|
return -4;
|
|
*pbpp = bpp;
|
|
*pMshift = Mshift;
|
|
return 0;
|
|
}
|
|
|
|
static inline
|
|
int decode_set_size(const char *str, int Mshift)
|
|
{
|
|
const char *base62 = str + 2;
|
|
int bitc = decode_base62_size(base62);
|
|
return decode_golomb_size(bitc, Mshift);
|
|
}
|
|
|
|
static
|
|
int decode_set(const char *str, int Mshift, unsigned *v)
|
|
{
|
|
const char *base62 = str + 2;
|
|
// separate base62+golomb stages, for reference
|
|
if (0) {
|
|
// base62
|
|
char bitv[decode_base62_size(base62)];
|
|
int bitc = decode_base62(base62, bitv);
|
|
if (bitc < 0)
|
|
return bitc;
|
|
// golomb
|
|
int c = decode_golomb(bitc, bitv, Mshift, v);
|
|
if (c < 0)
|
|
return c;
|
|
// delta
|
|
decode_delta(c, v);
|
|
return c;
|
|
}
|
|
// combined base62+golomb stage
|
|
int c = decode_base62_golomb(base62, Mshift, v);
|
|
if (c < 0)
|
|
return c;
|
|
// delta
|
|
decode_delta(c, v);
|
|
return c;
|
|
}
|
|
|
|
// Special decode_set version with LRU caching.
|
|
static
|
|
int cache_decode_set(const char *str, int Mshift, unsigned *v)
|
|
{
|
|
const int cache_size = 192;
|
|
const int pivot_size = 172;
|
|
unsigned *v_start = v, *v_end;
|
|
struct cache_ent {
|
|
struct cache_ent *next;
|
|
char *str;
|
|
unsigned hash;
|
|
int c;
|
|
unsigned *v;
|
|
unsigned short *dv;
|
|
};
|
|
static __thread
|
|
struct cache_ent *cache;
|
|
// lookup in the cache
|
|
struct cache_ent *cur = cache, *prev = NULL;
|
|
struct cache_ent *pivot_cur = NULL, *pivot_prev = NULL;
|
|
unsigned hash = str[0] | (str[2] << 8) | (str[3] << 16);
|
|
int count = 0;
|
|
while (cur) {
|
|
if (hash == cur->hash && strcmp(str, cur->str) == 0) {
|
|
// hit, move to front
|
|
if (cur != cache) {
|
|
prev->next = cur->next;
|
|
cur->next = cache;
|
|
cache = cur;
|
|
}
|
|
// stored as values
|
|
if (cur->v) {
|
|
memcpy(v, cur->v, cur->c * sizeof(*cur->v));
|
|
return cur->c;
|
|
}
|
|
// stored as short deltas
|
|
unsigned short *dv = cur->dv;
|
|
unsigned short *dv_end = dv + cur->c;
|
|
while (dv < dv_end)
|
|
*v++ = *dv++;
|
|
v = v_start;
|
|
decode_delta(cur->c, v);
|
|
return cur->c;
|
|
}
|
|
count++;
|
|
if (cur->next == NULL)
|
|
break;
|
|
prev = cur;
|
|
cur = cur->next;
|
|
if (count == pivot_size) {
|
|
pivot_cur = cur;
|
|
pivot_prev = prev;
|
|
}
|
|
}
|
|
// miss, decode
|
|
int c = decode_base62_golomb(str + 2, Mshift, v);
|
|
if (c <= 0)
|
|
return c;
|
|
v_end = v_start + c;
|
|
// truncate
|
|
if (count >= cache_size) {
|
|
free(cur);
|
|
prev->next = NULL;
|
|
}
|
|
// check delta
|
|
int delta = 1;
|
|
while (v < v_end) {
|
|
if (*v++ > 65535) {
|
|
delta = 0;
|
|
break;
|
|
}
|
|
}
|
|
v = v_start;
|
|
// new entry
|
|
cur = malloc(sizeof(*cur) + strlen(str) + 1 +
|
|
c * (delta ? sizeof *cur->dv : sizeof *cur->v));
|
|
if (cur == NULL) {
|
|
decode_delta(c, v);
|
|
return c;
|
|
}
|
|
cur->c = c;
|
|
if (delta) {
|
|
cur->v = NULL;
|
|
unsigned short *dv = cur->dv = (unsigned short *)(cur + 1);
|
|
while (v < v_end)
|
|
*dv++ = *v++;
|
|
v = v_start;
|
|
decode_delta(c, v);
|
|
cur->str = (char *) dv;
|
|
}
|
|
else {
|
|
cur->dv = NULL;
|
|
cur->v = (unsigned *)(cur + 1);
|
|
decode_delta(c, v);
|
|
memcpy(cur->v, v, c * sizeof(*v));
|
|
cur->str = (char *)(cur->v + c);
|
|
}
|
|
strcpy(cur->str, str);
|
|
cur->hash = hash;
|
|
// pivotal insertion!
|
|
if (count >= cache_size) {
|
|
cur->next = pivot_cur;
|
|
pivot_prev->next = cur;
|
|
}
|
|
// early bird, push to front
|
|
else {
|
|
cur->next = cache;
|
|
cache = cur;
|
|
}
|
|
return c;
|
|
}
|
|
|
|
static
|
|
int downsample_set(int c, unsigned *v, int bpp)
|
|
{
|
|
unsigned mask = (1 << bpp) - 1;
|
|
maskv(c, v, mask);
|
|
sortv(c, v);
|
|
return uniqv(c, v);
|
|
}
|
|
|
|
#ifdef SELF_TEST
|
|
static
|
|
void test_set()
|
|
{
|
|
unsigned rnd_v[] = {
|
|
0x020a, 0x07e5, 0x3305, 0x35f5,
|
|
0x4980, 0x4c4f, 0x74ef, 0x7739,
|
|
0x82ae, 0x8415, 0xa3e7, 0xb07e,
|
|
0xb584, 0xb89f, 0xbb40, 0xf39e,
|
|
};
|
|
int rnd_c = sizeof rnd_v / sizeof *rnd_v;
|
|
// encode
|
|
int bpp = 16;
|
|
char base62[encode_set_size(rnd_c, bpp)];
|
|
int len = encode_set(rnd_c, rnd_v, bpp, base62);
|
|
assert(len > 0);
|
|
fprintf(stderr, "len=%d set=%s\n", len, base62);
|
|
// decode
|
|
int Mshift = bpp;
|
|
int rc = decode_set_init(base62, &bpp, &Mshift);
|
|
assert(rc == 0);
|
|
assert(bpp == 16);
|
|
assert(Mshift < bpp);
|
|
int c = decode_set_size(base62, Mshift);
|
|
assert(c >= rnd_c);
|
|
unsigned v[c];
|
|
c = decode_set(base62, Mshift, v);
|
|
// Decoded values must match.
|
|
assert(c == rnd_c);
|
|
int i;
|
|
for (i = 0; i < c; i++)
|
|
assert(v[i] == rnd_v[i]);
|
|
// Cached version.
|
|
c = cache_decode_set(base62, Mshift, v);
|
|
assert(c == rnd_c);
|
|
for (i = 0; i < c; i++)
|
|
assert(v[i] == rnd_v[i]);
|
|
fprintf(stderr, "%s: set test OK\n", __FILE__);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* API routines start here.
|
|
*/
|
|
|
|
#include "set.h"
|
|
|
|
// main API routine
|
|
int rpmsetcmp(const char *str1, const char *str2)
|
|
{
|
|
if (strncmp(str1, "set:", 4) == 0)
|
|
str1 += 4;
|
|
if (strncmp(str2, "set:", 4) == 0)
|
|
str2 += 4;
|
|
// initialize decoding
|
|
int bpp1, Mshift1;
|
|
int bpp2, Mshift2;
|
|
if (decode_set_init(str1, &bpp1, &Mshift1) < 0)
|
|
return -3;
|
|
if (decode_set_init(str2, &bpp2, &Mshift2) < 0)
|
|
return -4;
|
|
// make room for hash values
|
|
unsigned v1buf[decode_set_size(str1, Mshift1)], *v1 = v1buf;
|
|
unsigned v2buf[decode_set_size(str2, Mshift2)], *v2 = v2buf;
|
|
// decode hash values
|
|
// str1 comes on behalf of provides, decode with caching
|
|
int c1 = cache_decode_set(str1, Mshift1, v1);
|
|
if (c1 < 0)
|
|
return -3;
|
|
int c2 = decode_set(str2, Mshift2, v2);
|
|
if (c2 < 0)
|
|
return -4;
|
|
// adjust for comparison
|
|
if (bpp1 > bpp2) {
|
|
bpp1 = bpp2;
|
|
c1 = downsample_set(c1, v1, bpp1);
|
|
}
|
|
if (bpp2 > bpp1) {
|
|
bpp2 = bpp1;
|
|
c2 = downsample_set(c2, v2, bpp2);
|
|
}
|
|
// compare
|
|
int ge = 1;
|
|
int le = 1;
|
|
unsigned *v1end = v1 + c1;
|
|
unsigned *v2end = v2 + c2;
|
|
while (v1 < v1end && v2 < v2end) {
|
|
if (*v1 < *v2) {
|
|
le = 0;
|
|
v1++;
|
|
}
|
|
else if (*v1 > *v2) {
|
|
ge = 0;
|
|
v2++;
|
|
}
|
|
else {
|
|
v1++;
|
|
v2++;
|
|
}
|
|
}
|
|
// return
|
|
if (v1 < v1end)
|
|
le = 0;
|
|
if (v2 < v2end)
|
|
ge = 0;
|
|
if (le && ge)
|
|
return 0;
|
|
if (ge)
|
|
return 1;
|
|
if (le)
|
|
return -1;
|
|
return -2;
|
|
}
|
|
|
|
/*
|
|
* Simple API for creating set-versions.
|
|
*/
|
|
|
|
#include "system.h"
|
|
#include "rpmlib.h"
|
|
|
|
// Internally, "struct set" is just a bag of strings and their hash values.
|
|
struct set {
|
|
int c;
|
|
struct sv {
|
|
const char *s;
|
|
unsigned v;
|
|
} *sv;
|
|
};
|
|
|
|
struct set *set_new()
|
|
{
|
|
struct set *set = xmalloc(sizeof *set);
|
|
set->c = 0;
|
|
set->sv = NULL;
|
|
return set;
|
|
}
|
|
|
|
void set_add(struct set *set, const char *sym)
|
|
{
|
|
const int delta = 1024;
|
|
if ((set->c & (delta - 1)) == 0)
|
|
set->sv = xrealloc(set->sv, sizeof(*set->sv) * (set->c + delta));
|
|
set->sv[set->c].s = xstrdup(sym);
|
|
set->sv[set->c].v = 0;
|
|
set->c++;
|
|
}
|
|
|
|
struct set *set_free(struct set *set)
|
|
{
|
|
if (set) {
|
|
int i;
|
|
for (i = 0; i < set->c; i++)
|
|
set->sv[i].s = _free(set->sv[i].s);
|
|
set->sv = _free(set->sv);
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
// This routine does the whole job.
|
|
const char *set_fini(struct set *set, int bpp)
|
|
{
|
|
if (set->c < 1)
|
|
return NULL;
|
|
if (bpp < 10)
|
|
return NULL;
|
|
if (bpp > 32)
|
|
return NULL;
|
|
unsigned mask = (bpp < 32) ? (1u << bpp) - 1 : ~0u;
|
|
// Jenkins' one-at-a-time hash
|
|
unsigned int hash(const char *str)
|
|
{
|
|
unsigned int hash = 0x9e3779b9;
|
|
const unsigned char *p = (const unsigned char *) str;
|
|
while (*p) {
|
|
hash += *p++;
|
|
hash += (hash << 10);
|
|
hash ^= (hash >> 6);
|
|
}
|
|
hash += (hash << 3);
|
|
hash ^= (hash >> 11);
|
|
hash += (hash << 15);
|
|
return hash;
|
|
}
|
|
// hash sv strings
|
|
int i;
|
|
for (i = 0; i < set->c; i++)
|
|
set->sv[i].v = hash(set->sv[i].s) & mask;
|
|
// sort by hash value
|
|
int cmp(const void *arg1, const void *arg2)
|
|
{
|
|
struct sv *sv1 = (struct sv *) arg1;
|
|
struct sv *sv2 = (struct sv *) arg2;
|
|
if (sv1->v > sv2->v)
|
|
return 1;
|
|
if (sv2->v > sv1->v)
|
|
return -1;
|
|
return 0;
|
|
}
|
|
qsort(set->sv, set->c, sizeof *set->sv, cmp);
|
|
// warn on hash collisions
|
|
for (i = 0; i < set->c - 1; i++) {
|
|
if (set->sv[i].v != set->sv[i+1].v)
|
|
continue;
|
|
if (strcmp(set->sv[i].s, set->sv[i+1].s) == 0)
|
|
continue;
|
|
fprintf(stderr, "warning: hash collision: %s %s\n",
|
|
set->sv[i].s, set->sv[i+1].s);
|
|
}
|
|
// encode
|
|
unsigned v[set->c];
|
|
for (i = 0; i < set->c; i++)
|
|
v[i] = set->sv[i].v;
|
|
int c = uniqv(set->c, v);
|
|
char base62[encode_set_size(c, bpp)];
|
|
int len = encode_set(c, v, bpp, base62);
|
|
if (len < 0)
|
|
return NULL;
|
|
return xstrdup(base62);
|
|
}
|
|
|
|
#ifdef SELF_TEST
|
|
static
|
|
void test_api()
|
|
{
|
|
struct set *set1 = set_new();
|
|
set_add(set1, "mama");
|
|
set_add(set1, "myla");
|
|
set_add(set1, "ramu");
|
|
const char *str10 = set_fini(set1, 16);
|
|
fprintf(stderr, "set10=%s\n", str10);
|
|
|
|
int cmp;
|
|
struct set *set2 = set_new();
|
|
set_add(set2, "myla");
|
|
set_add(set2, "mama");
|
|
const char *str20 = set_fini(set2, 16);
|
|
fprintf(stderr, "set20=%s\n", str20);
|
|
cmp = rpmsetcmp(str10, str20);
|
|
assert(cmp == 1);
|
|
|
|
set_add(set2, "ramu");
|
|
const char *str21 = set_fini(set2, 16);
|
|
fprintf(stderr, "set21=%s\n", str21);
|
|
cmp = rpmsetcmp(str10, str21);
|
|
assert(cmp == 0);
|
|
|
|
set_add(set2, "baba");
|
|
const char *str22 = set_fini(set2, 16);
|
|
cmp = rpmsetcmp(str10, str22);
|
|
assert(cmp == -1);
|
|
|
|
set_add(set1, "deda");
|
|
const char *str11 = set_fini(set1, 16);
|
|
cmp = rpmsetcmp(str11, str22);
|
|
assert(cmp == -2);
|
|
|
|
set1 = set_free(set1);
|
|
set2 = set_free(set2);
|
|
str10 = _free(str10);
|
|
str11 = _free(str11);
|
|
str20 = _free(str20);
|
|
str21 = _free(str21);
|
|
str22 = _free(str22);
|
|
|
|
fprintf(stderr, "%s: api test OK\n", __FILE__);
|
|
}
|
|
#endif
|
|
|
|
#ifdef SELF_TEST
|
|
int main()
|
|
{
|
|
test_base62();
|
|
test_golomb();
|
|
test_base62_golomb();
|
|
test_delta();
|
|
test_aux();
|
|
test_set();
|
|
test_api();
|
|
return 0;
|
|
}
|
|
#endif
|
|
// ex: set ts=8 sts=4 sw=4 noet:
|