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- no second ata_hard_reset() call, saves ~2.5 seconds flash boot time (please test)

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- Jens' new assembler code in copy_read_sectors(), but still disabled


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@4358 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Jörg Hohensohn 2004-03-10 14:15:14 +00:00
parent dcdb89ca9f
commit 5fb1e1024f
1 changed files with 106 additions and 73 deletions
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165
firmware/drivers/ata.c
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@ -174,92 +174,129 @@ static void copy_read_sectors(unsigned char* buf,
__attribute__ ((section (".icode")));
static void copy_read_sectors(unsigned char* buf, int wordcount)
{
unsigned short tmp = 0; /* have to init to prevent warning? */
#ifdef PREFER_C
unsigned short tmp = 0;
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 9 assembler instructions */
/* takes 13 clock cycles because of 2 pipeline stalls */
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
/* I can bring it down to 7 instructions/loop, and exploit pipeline */
asm (
"mov #1, r0 \n" /* r0 = 1; */
/* correct for the "early increment" below */
"add #-2,%2 \n" /* buf -= 2; */
"add #-2,%3 \n" /* bufend -= 2; */
"loop_b: \n"
"mov.w @%1,%0 \n" /* tmp = ATA_DATA; */
/* Now we're reading from the bus, I do something independent we
need later, to avoid pipeline stall */
"add #0x02,%2 \n" /* buf += 2; */
"cmp/hs %3,%2 \n" /* if (buf < bufend) */
/* now use the read result */
"mov.b %0,@%2 \n" /* buf[0] = lowbyte(tmp); */
"shlr8 %0 \n" /* tmp >>= 8; */
"mov.b %0,@(r0,%2) \n" /* buf[r0] = lowbyte(tmp); */
"bf loop_b \n" /* goto loop_b; */
: /* 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 */
/* takes 11 clock cycles because of 2 pipeline stalls */
*wbuf = SWAB16(ATA_DATA);
} while (++wbuf < wbufend); /* tail loop is faster */
}
#else
/* I can bring it down to 9 instructions for 2 loops, and pipeline */
/* turbo-charged assembler version */
/* this assumes wordcount to be a multiple of 4 */
asm (
"mov #2, r0 \n" /* r0 = 2 */
/* correct for the "early increment" below */
"add #-4,%2 \n" /* wbuf -= 4; */
"bra enter_loop \n" /* goto enter_loop, after next instr. */
"add #-4,%3 \n" /* wbufend -= 4; */
"loop_w: \n"
/* use read result and store, from last round */
"swap.b %0,%0 \n" /* endian_swap(tmp); */
"mov.w %0,@(r0,%2) \n" /* wbuf[r0] = tmp; */
"enter_loop: \n"
"mov.w @%1,%0 \n" /* tmp = ATA_DATA; */
/* keep the pipeline busy with 2 independent instructions */
"add #0x04,%2 \n" /* wbuf += 4; */
"cmp/hs %3,%2 \n" /* if (wbuf < wbufend) */
"swap.b %0,%0 \n" /* endian_swap(tmp); */
"mov.w %0,@%2 \n" /* wbuf[0] = tmp; */
/* unrolled, do one more */
"mov.w @%1,%0 \n" /* tmp = ATA_DATA; */
/* use and store later, to keep pipeline busy */
"bf loop_w \n" /* goto loop_w; */
"swap.b %0,%0 \n" /* endian_swap(tmp); */
"mov.w %0,@(r0,%2) \n" /* wbuf[r0] = tmp; */
"add %1,%1 \n" /* wordcount -> bytecount */
"add %0,%1 \n" /* bytecount -> bufend */
"mov %0,r0 \n"
"tst #1,r0 \n" /* 16-bit aligned ? */
"bt .aligned \n" /* yes, do word copy */
".align 2 \n"
/* not 16-bit aligned */
"mov #-1,r3 \n" /* prepare a bit mask for high byte */
"extu.b r3,r3 \n"
"swap.b r3,r3 \n" /* r3 = 0x0000FF00 */
"mov.w @%2,r2 \n" /* read first word (1st round) */
"add #-12,%1 \n" /* adjust end address for offsets */
"mov.b r2,@%0 \n" /* store low byte of first word */
"bra .start4_b \n" /* jump into loop after next instr. */
"add #-5,%0 \n" /* adjust for dest. offsets; now even */
".loop4_b: \n" /* main loop: copy 4 words in a row */
"mov.w @%2,r2 \n" /* read first word (2+ round) */
"and r3,r1 \n" /* get high byte of fourth word (2+ round) */
"extu.b r2,r0 \n" /* get low byte of first word (2+ round) */
"or r1,r0 \n" /* combine with high byte of fourth word */
"mov.w r0,@(4,%0) \n" /* store at buf[4] */
"nop \n" /* maintain alignment */
".start4_b: \n"
"mov.w @%2,r1 \n" /* read second word */
"and r3,r2 \n" /* get high byte of first word */
"extu.b r1,r0 \n" /* get low byte of second word */
"or r2,r0 \n" /* combine with high byte of first word */
"mov.w r0,@(6,%0) \n" /* store at buf[6] */
"add #8,%0 \n" /* buf += 8 */
"mov.w @%2,r2 \n" /* read third word */
"and r3,r1 \n" /* get high byte of second word */
"extu.b r2,r0 \n" /* get low byte of third word */
"or r1,r0 \n" /* combine with high byte of second word */
"mov.w r0,@%0 \n" /* store at buf[0] */
"cmp/hi %0,%1 \n" /* check for end */
"mov.w @%2,r1 \n" /* read fourth word */
"and r3,r2 \n" /* get high byte of third word */
"extu.b r1,r0 \n" /* get low byte of fourth word */
"or r2,r0 \n" /* combine with high byte of third word */
"mov.w r0,@(2,%0) \n" /* store at buf[2] */
"bt .loop4_b \n"
/* 24 instructions for 4 copies, takes 26 clock cycles */
/* avg. 6.5 cycles per word - 100% faster */
"swap.b r1,r0 \n" /* get high byte of last word */
"mov.b r0,@(4,%0) \n" /* and store it */
"bra .exit \n"
"nop \n"
".align 2 \n"
/* 16-bit aligned, loop(read and store word) */
".aligned: \n"
"mov.w @%2,r2 \n" /* read first word (1st round) */
"add #-12,%1 \n" /* adjust end address for offsets */
"bra .start4_w \n" /* jump into loop after next instr. */
"add #-6,%0 \n" /* adjust for destination offsets */
".loop4_w: \n" /* main loop: copy 4 words in a row */
"mov.w @%2,r2 \n" /* read first word (2+ round) */
"swap.b r1,r0 \n" /* swap fourth word (2+ round) */
"mov.w r0,@(4,%0) \n" /* store fourth word (2+ round) */
"nop \n" /* maintain alignment */
".start4_w: \n"
"mov.w @%2,r1 \n" /* read second word */
"swap.b r2,r0 \n" /* swap first word */
"mov.w r0,@(6,%0) \n" /* store first word in buf[6] */
"add #8,%0 \n" /* buf += 8 */
"mov.w @%2,r2 \n" /* read third word */
"swap.b r1,r0 \n" /* swap second word */
"mov.w r0,@%0 \n" /* store second word in buf[0] */
"cmp/hi %0,%1 \n" /* check for end */
"mov.w @%2,r1 \n" /* read fourth word */
"swap.b r2,r0 \n" /* swap third word */
"mov.w r0,@(2,%0) \n" /* store third word */
"bt .loop4_w \n"
/* 16 instructions for 4 copies, takes 18 clock cycles */
/* avg. 4.5 cycles per word - 144% faster */
"swap.b r1,r0 \n" /* swap fourth word (last round) */
"mov.w r0,@(4,%0) \n" /* and store it */
".exit: \n"
: /* outputs */
: /* inputs */
/* %0 */ "r"(tmp),
/* %1 */ "r"(&ATA_DATA),
/* %2 */ "r"(wbuf),
/* %3 */ "r"(wbufend)
: /* trashed */
"r0"
/* %0 */ "r"(buf),
/* %1 */ "r"(wordcount),
/* %2 */ "r"(&ATA_DATA)
: /*trashed */
"r0","r1","r2","r3"
);
#endif
}
}
int ata_read_sectors(unsigned long start,
@ -958,14 +995,10 @@ int ata_init(void)
if (coldstart)
{
/* Reset both master and slave, we don't yet know what's in */
/* this is safe because non-present devices don't report busy */
/* This should reset both master and slave, we don't yet know what's in */
ata_device = 0;
if (ata_hard_reset())
return -1;
ata_device = SELECT_DEVICE1;
if (ata_hard_reset())
return -2;
}
rc = master_slave_detect();