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Assembler optimized copy_read_sectors() gives another speedup of factor 1.4 for aligned and 1.2 for misaligned. Including my previous change the file reading is now nearly twice as fast compared to when I started this. -> Less disk uptime, longer battery life.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@4281 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Jörg Hohensohn 2004-01-27 09:12:51 +00:00
parent 0a8fef9a24
commit cb570b9263
1 changed files with 103 additions and 7 deletions
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108
firmware/drivers/ata.c
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@ -162,33 +162,129 @@ static int wait_for_end_of_transfer(void)
}
/*
0x090156A8: 0x4F22 sts.l pr,@-r15
0x090156AA: 0x6243 mov r4,r2
0x090156AC: 0x6023 mov r2,r0
0x090156AE: 0xC901 and #0x01,r0
0x090156B0: 0x2008 tst r0,r0
0x090156B2: 0x8911 bt 0x090156D8
0x090156B4: 0x6153 mov r5,r1
0x090156B6: 0x311C add r1,r1
0x090156B8: 0x6523 mov r2,r5
0x090156BA: 0x351C add r1,r5
0x090156BC: 0xD30E mov.l @(0x03C,pc),r3 ; 0x090156F8 (0x06104100)
0x090156BE: 0x0009 nop
0x090156C0: 0x6131 mov.w @r3,r1
0x090156C2: 0x611D extu.w r1,r1
0x090156C4: 0x2210 mov.b r1,@r2
0x090156C6: 0x7201 add #0x01,r2
0x090156C8: 0x4119 shlr8 r1
0x090156CA: 0x2210 mov.b r1,@r2
0x090156CC: 0x7201 add #0x01,r2
0x090156CE: 0x3252 cmp/hs r5,r2
0x090156D0: 0x8BF6 bf 0x090156C0
0x090156D2: 0xA00F bra 0x090156F4
0x090156D4: 0x4F26 lds.l @r15+,pr
0x090156D6: 0x0009 nop
0x090156D8: 0x6423 mov r2,r4
0x090156DA: 0x6153 mov r5,r1
0x090156DC: 0x311C add r1,r1
0x090156DE: 0x6543 mov r4,r5
0x090156E0: 0x351C add r1,r5
0x090156E2: 0xD205 mov.l @(0x018,pc),r2 ; 0x090156F8 (0x06104100)
0x090156E4: 0x6121 mov.w @r2,r1
0x090156E6: 0x611F exts.w r1,r1
0x090156E8: 0x6118 swap.b r1,r1
0x090156EA: 0x2411 mov.w r1,@r4
0x090156EC: 0x7402 add #0x02,r4
0x090156EE: 0x3452 cmp/hs r5,r4
0x090156F0: 0x8BF8 bf 0x090156E4
0x090156F2: 0x4F26 lds.l @r15+,pr
0x090156F4: 0x000B rts
0x090156F6: 0x0009 nop
0x090156F8: 0x0610 .long 0x06104100 ; 0x090156E0
0x090156FA: 0x4100
*/
/* the tight loop of ata_read_sectors(), to avoid the whole in IRAM */
static void copy_read_sectors(unsigned char* buf,
int wordcount)
__attribute__ ((section (".icode")));
static void copy_read_sectors(unsigned char* buf, int wordcount)
{
if (wordcount <= 0)
return; /* should never happen, but to protect my tail loop */
unsigned short tmp = 0; /* have to init to prevent warning? */
if ( (unsigned int)buf & 1)
{
{ /* not 16-bit aligned, copy byte by byte */
unsigned char* bufend = buf + wordcount*2;
#ifdef PREFER_C
do
{ /* loop compiles to 8 assembler instructions */
unsigned short tmp = ATA_DATA;
{ /* loop compiles to 9 assembler instructions */
tmp = ATA_DATA;
*buf++ = tmp & 0xff; /* I assume big endian */
*buf++ = tmp >> 8; /* and don't use the SWAB16 macro */
} while (buf < bufend); /* tail loop is faster */
#else
asm (
"mov #1, r0 \n"
"loop_b: \n"
"mov.w @%1,%0 \n"
"mov.b %0,@%2 \n"
"shlr8 %0 \n"
"mov.b %0,@(r0,%2) \n"
"add #0x02,%2 \n"
"cmp/hs %3,%2 \n"
"bf loop_b \n"
: /* outputs */
: /* inputs */
/* %0 */ "r"(tmp),
/* %1 */ "r"(&ATA_DATA),
/* %2 */ "r"(buf),
/* %3 */ "r"(bufend)
: /* trashed */
"r0"
);
#endif
}
else
{
{ /* 16-bit aligned, can do faster copy */
unsigned short* wbuf = (unsigned short*)buf;
unsigned short* wbufend = wbuf + wordcount;
#ifdef PREFER_C
do
{ /* loop compiles to 7 assembler instructions */
*wbuf = SWAB16(ATA_DATA);
} while (++wbuf < wbufend); /* tail loop is faster */
#else
asm (
"mov #2, r0 \n"
"loop_w: \n"
"mov.w @%1,%0 \n"
"swap.b %0,%0 \n"
"mov.w %0,@%2 \n"
"mov.w @%1,%0 \n" /* unrolled, do one more */
"swap.b %0,%0 \n"
"mov.w %0,@(r0,%2) \n"
"add #0x04,%2 \n"
"cmp/hs %3,%2 \n"
"bf loop_w \n"
: /* outputs */
: /* inputs */
/* %0 */ "r"(tmp),
/* %1 */ "r"(&ATA_DATA),
/* %2 */ "r"(wbuf),
/* %3 */ "r"(wbufend)
: /* trashed */
"r0"
);
#endif
}
}