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Faster Q1.31 multiply for ARM. Add some ARM asm windowing code. Simply replacing c code with loop unrolled + load/store multiple instructions makes a surprising difference on PP. Also, add comments to the windowing code.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@14365 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Michael Giacomelli 2007-08-16 03:33:15 +00:00
parent 1d1d9a8491
commit 8159b9ee9a
2 changed files with 49 additions and 6 deletions
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49
apps/codecs/libwma/wmadeci.c
View file

@ -378,12 +378,47 @@ void ff_imdct_calc(MDCTContext *s,
*
*/
#ifdef CPU_ARM
static inline
void vector_fmul_add_add(fixed32 *dst, const fixed32 *data, const fixed32 *window, int n)
{
while (n>=2) {
asm volatile ("ldmia %[d]!, {r0, r1};"
"ldmia %[w]!, {r4, r5};"
/*consume the first data and window value so we can use those registers again */
"smull r8, r9, r0, r4;"
"ldmia %[dst], {r0, r4};"
"add r0, r0, r9, lsl #1;" /* *dst=*dst+(r9<<1)*/
"smull r8, r9, r1, r5;"
"add r1, r4, r9, lsl #1;"
"stmia %[dst]!, {r0, r1};"
: [d] "+r" (data), [w] "+r" (window), [dst] "+r" (dst)
: : "r0", "r1",
"r4", "r5", "r8", "r9",
"memory", "cc");
n -= 2;
}
while(n>0) {
*dst = fixmul32b(*data, *window);
data++;
window++;
n--;
}
}
#else
static inline void vector_fmul_add_add(fixed32 *dst, const fixed32 *src0, const fixed32 *src1, int len){
int i;
for(i=0; i<len; i++)
dst[i] = fixmul32b(src0[i], src1[i]) + dst[i];
}
#endif
/* TODO: Adapt the above to work with this */
static inline void vector_fmul_reverse(fixed32 *dst, const fixed32 *src0, const fixed32 *src1, int len){
int i;
src1 += len-1;
@ -391,11 +426,15 @@ static inline void vector_fmul_reverse(fixed32 *dst, const fixed32 *src0, const
dst[i] = fixmul32b(src0[i], src1[-i]);
}
/**
* Apply MDCT window and add into output.
*
* We ensure that when the windows overlap their squared sum
* is always 1 (MDCT reconstruction rule).
*
* The Vorbis I spec has a great diagram explaining this process.
* See section 1.3.2.3 of http://xiph.org/vorbis/doc/Vorbis_I_spec.html
*/
static void wma_window(WMADecodeContext *s, fixed32 *in, fixed32 *out)
{
@ -403,6 +442,7 @@ static inline void vector_fmul_reverse(fixed32 *dst, const fixed32 *src0, const
int block_len, bsize, n;
/* left part */
/*previous block was larger, so we'll use the size of the current block to set the window size*/
if (s->block_len_bits <= s->prev_block_len_bits) {
block_len = s->block_len;
bsize = s->frame_len_bits - s->block_len_bits;
@ -410,7 +450,9 @@ static inline void vector_fmul_reverse(fixed32 *dst, const fixed32 *src0, const
vector_fmul_add_add(out, in, s->windows[bsize], block_len);
} else {
/*previous block was smaller or the same size, so use it's size to set the window length*/
block_len = 1 << s->prev_block_len_bits;
/*find the middle of the two overlapped blocks, this will be the first overlapped sample*/
n = (s->block_len - block_len) / 2;
bsize = s->frame_len_bits - s->prev_block_len_bits;
@ -418,7 +460,10 @@ static inline void vector_fmul_reverse(fixed32 *dst, const fixed32 *src0, const
memcpy(out+n+block_len, in+n+block_len, n*sizeof(fixed32));
}
/* Advance to the end of the current block and prepare to window it for the next block.
* Since the window function needs to be reversed, we do it backwards starting with the
* last sample and moving towards the first
*/
out += s->block_len;
in += s->block_len;
@ -1124,7 +1169,7 @@ static int wma_decode_block(WMADecodeContext *s)
int nb_coefs[MAX_CHANNELS];
fixed32 mdct_norm;
// printf("***decode_block: %d:%d (%d)\n", s->frame_count - 1, s->block_num, s->block_len);
DEBUGF("***decode_block: %d of (%d samples) (%d)\n", s->block_num, s->frame_len, s->block_len);
/* compute current block length */
if (s->use_variable_block_len)

6
apps/codecs/libwma/wmafixed.h
View file

@ -67,11 +67,9 @@ long fsincos(unsigned long phase, fixed32 *cos);
uint32_t __lo; \
int32_t __result; \
asm ("smull %0, %1, %3, %4\n\t" \
"movs %0, %0, lsr %5\n\t" \
"adc %2, %0, %1, lsl %6" \
"movs %2, %1, lsl #1" \
: "=&r" (__lo), "=&r" (__hi), "=r" (__result) \
: "%r" (x), "r" (y), \
"M" (31), "M" (32 - 31) \
: "%r" (x), "r" (y) \
: "cc"); \
__result; \
})