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Add mempcpy implementation

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A GNU extension that returns dst + size instead of dst. It's a nice
shortcut when copying strings with a known size or back-to-back blocks
and you have to do it often.

May of course be called directly or alternately through
__builtin_mempcpy in some compiler versions.

For ASM on native targets, it is implemented as an alternate entrypoint
to memcpy which adds minimal code and overhead.

Change-Id: I4cbb3483f6df3c1007247fe0a95fd7078737462b
This commit is contained in:
Michael Sevakis 2014-08-06 04:26:52 -04:00
parent 7d1a47cf13
commit 77b3625763
8 changed files with 99 additions and 4 deletions
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4
firmware/asm/SOURCES
View file

@ -7,6 +7,10 @@ memset.c
strlen.c
#endif
#if defined(WIN32) || defined(APPLICATION)
mempcpy.c
#endif
#if (defined(SANSA_E200) || defined(GIGABEAT_F) || defined(GIGABEAT_S) || \
defined(CREATIVE_ZVx) || defined(SANSA_CONNECT) || defined(SANSA_FUZEPLUS) || \
defined(COWON_D2) || defined(MINI2440) || defined(SAMSUNG_YPR0) || \

10
firmware/asm/arm/memcpy.S
View file

@ -36,17 +36,25 @@
#endif
/* Prototype: void *memcpy(void *dest, const void *src, size_t n); */
/* Prototype: void *mempcpy(void *dest, const void *src, size_t n); */
.section .icode,"ax",%progbits
.align 2
.global memcpy
.type memcpy,%function
.global mempcpy
.type mempcpy,%function
mempcpy:
add r3, r0, r2
stmfd sp!, {r3, r4, lr}
b 0f
memcpy:
stmfd sp!, {r0, r4, lr}
subs r2, r2, #4
0: subs r2, r2, #4
blt 8f
ands ip, r0, #3
bne 9f

10
firmware/asm/m68k/memcpy.S
View file

@ -27,6 +27,8 @@
.global memcpy
.global __memcpy_fwd_entry
.type memcpy,@function
.global mempcpy
.type mempcpy,@function
/* Copies <length> bytes of data in memory from <source> to <dest>
* This version is optimized for speed
@ -53,6 +55,14 @@
* long+3) it writes longwords only. Same goes for word aligned destinations
* if FULLSPEED is undefined.
*/
mempcpy:
move.l (4,%sp),%a1 /* Destination */
move.l (8,%sp),%a0 /* Source */
move.l (12,%sp),%d1 /* Length */
add.l %d1,(4,%sp) /* retval=Destination + Length */
bra.b __memcpy_fwd_entry
memcpy:
move.l (4,%sp),%a1 /* Destination */
move.l (8,%sp),%a0 /* Source */

47
firmware/asm/mempcpy.c Normal file
View file

@ -0,0 +1,47 @@
/*
FUNCTION
<<mempcpy>>---copy memory regions and return end pointer
ANSI_SYNOPSIS
#include <string.h>
void* mempcpy(void *<[out]>, const void *<[in]>, size_t <[n]>);
TRAD_SYNOPSIS
void *mempcpy(<[out]>, <[in]>, <[n]>
void *<[out]>;
void *<[in]>;
size_t <[n]>;
DESCRIPTION
This function copies <[n]> bytes from the memory region
pointed to by <[in]> to the memory region pointed to by
<[out]>.
If the regions overlap, the behavior is undefined.
RETURNS
<<mempcpy>> returns a pointer to the byte following the
last byte copied to the <[out]> region.
PORTABILITY
<<mempcpy>> is a GNU extension.
<<mempcpy>> requires no supporting OS subroutines.
*/
#include "config.h"
#include "_ansi.h" /* for _DEFUN */
#include <string.h>
/* This may be conjoined with memcpy in <cpu>/memcpy.S to get it nearly for
free */
_PTR
_DEFUN (mempcpy, (dst0, src0, len0),
_PTR dst0 _AND
_CONST _PTR src0 _AND
size_t len0)
{
return memcpy(dst0, src0, len0) + len0;
}

11
firmware/asm/mips/memcpy.S
View file

@ -43,8 +43,16 @@
.global memcpy
.type memcpy, %function
.global mempcpy
.type mempcpy, %function
.set noreorder
mempcpy:
slti t0, a2, 8 # Less than 8?
bne t0, zero, last8
addu v0, a0, a2 # exit value = s1 + n
b 1f
xor t0, a1, a0 # Find a0/a1 displacement (fill delay)
memcpy:
slti t0, a2, 8 # Less than 8?
@ -52,7 +60,8 @@ memcpy:
move v0, a0 # Setup exit value before too late
xor t0, a1, a0 # Find a0/a1 displacement
andi t0, 0x3
1: andi t0, 0x3
bne t0, zero, shift # Go handle the unaligned case
subu t1, zero, a1
andi t1, 0x3 # a0/a1 are aligned, but are we

8
firmware/asm/sh/memcpy.S
View file

@ -24,8 +24,10 @@
.align 2
.global _memcpy
.global _mempcpy
.global ___memcpy_fwd_entry
.type _memcpy,@function
.type _mempcpy,@function
/* Copies <length> bytes of data in memory from <source> to <dest>
* This version is optimized for speed
@ -51,6 +53,10 @@
* The instruction order is devised in a way to utilize the pipelining
* of the SH1 to the max. The routine also tries to utilize fast page mode.
*/
_mempcpy:
mov r4,r7 /* store dest + length for returning */
bra ___memcpy_fwd_entry
add r6,r7
_memcpy:
mov r4,r7 /* store dest for returning */
@ -217,3 +223,5 @@ ___memcpy_fwd_entry:
mov r7,r0 /* return dest start address */
.end:
.size _memcpy,.end-_memcpy
.size _mempcpy,.end-_mempcpy

12
firmware/include/string-extra.h
View file

@ -18,8 +18,8 @@
* KIND, either express or implied.
*
****************************************************************************/
#ifndef STRING_EXTRA_H
#define STRING_EXTRA_H
#include <string.h>
#include "strlcpy.h"
#include "strlcat.h"
@ -27,3 +27,11 @@
#include "strcasestr.h"
#include "strtok_r.h"
#include "memset16.h"
#if defined(WIN32) || defined(APPLICATION)
#ifndef mempcpy
#define mempcpy __builtin_mempcpy
#endif
#endif
#endif /* STRING_EXTRA_H */

1
firmware/libc/include/string.h
View file

@ -20,6 +20,7 @@ extern "C" {
_PTR _EXFUN(memchr,(const _PTR, int, size_t));
int _EXFUN(memcmp,(const _PTR, const _PTR, size_t));
_PTR _EXFUN(memcpy,(_PTR, const _PTR, size_t));
_PTR _EXFUN(mempcpy,(_PTR, const _PTR, size_t));
_PTR _EXFUN(memmove,(_PTR, const _PTR, size_t));
_PTR _EXFUN(memset,(_PTR, int, size_t));
char *_EXFUN(strcat,(char *, const char *));