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r2960: during a lunchtime discussion I found out that all powerpc processors

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can correctly (and quickly!) handle unaligned little endian memory
accesses, just like i386. This should reduce code size and speeds
things up quite a lot on ppc, at the expense of some inline asm code
(whcih means it only works with gcc)
This commit is contained in:
Andrew Tridgell 2004-10-14 05:26:35 +00:00 committed by Gerald (Jerry) Carter
parent 2f1e9954e3
commit 2a0c427c2b
1 changed files with 47 additions and 2 deletions
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49
source/include/byteorder.h
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@ -93,11 +93,45 @@ it also defines lots of intermediate macros, just ignore those :-)
*/
/*
on powerpc we can use the magic instructions to load/store
in little endian
*/
#if (defined(__powerpc__) && defined(__GNUC__))
static __inline__ uint16_t ld_le16(const uint16_t *addr)
{
uint16_t val;
__asm__ ("lhbrx %0,0,%1" : "=r" (val) : "r" (addr), "m" (*addr));
return val;
}
static __inline__ void st_le16(uint16_t *addr, const uint16_t val)
{
__asm__ ("sthbrx %1,0,%2" : "=m" (*addr) : "r" (val), "r" (addr));
}
static __inline__ uint32_t ld_le32(const uint32_t *addr)
{
uint32_t val;
__asm__ ("lwbrx %0,0,%1" : "=r" (val) : "r" (addr), "m" (*addr));
return val;
}
static __inline__ void st_le32(uint32_t *addr, const uint32_t val)
{
__asm__ ("stwbrx %1,0,%2" : "=m" (*addr) : "r" (val), "r" (addr));
}
#define HAVE_ASM_BYTEORDER 1
#endif
#undef CAREFUL_ALIGNMENT
/* we know that the 386 can handle misalignment and has the "right"
byteorder */
#ifdef __i386__
#if defined(__i386__)
#define CAREFUL_ALIGNMENT 0
#endif
@ -110,8 +144,19 @@ it also defines lots of intermediate macros, just ignore those :-)
#define PVAL(buf,pos) (CVAL(buf,pos))
#define SCVAL(buf,pos,val) (CVAL_NC(buf,pos) = (val))
#if HAVE_ASM_BYTEORDER
#if CAREFUL_ALIGNMENT
#define _PTRPOS(buf,pos) (((const uint8_t *)buf)+(pos))
#define SVAL(buf,pos) ld_le16((const uint16_t *)_PTRPOS(buf,pos))
#define IVAL(buf,pos) ld_le32((const uint32_t *)_PTRPOS(buf,pos))
#define SSVAL(buf,pos,val) st_le16((uint16_t *)__PTRPOS(buf,pos), val)
#define SIVAL(buf,pos,val) st_le32((uint32_t *)__PTRPOS(buf,pos), val)
#define SVALS(buf,pos) ((int16_t)SVAL(buf,pos))
#define IVALS(buf,pos) ((int32_t)IVAL(buf,pos))
#define SSVALS(buf,pos,val) SSVAL((buf),(pos),((int16_t)(val)))
#define SIVALS(buf,pos,val) SIVAL((buf),(pos),((int32_t)(val)))
#elif CAREFUL_ALIGNMENT
#define SVAL(buf,pos) (PVAL(buf,pos)|PVAL(buf,(pos)+1)<<8)
#define IVAL(buf,pos) (SVAL(buf,pos)|SVAL(buf,(pos)+2)<<16)