devs/foxbox
1
0
Fork 0
forked from len0rd/rockbox
Code Pull requests Activity

TDSpeed: Minor assembly optimization to frame fade on Coldfire.

Browse source 
Makes quite a huge difference to get rid of 64-bit math in a hot
area. Cuts about 12 MHz. Generic routine generates good code on
ARM and asm cuts no instructions there.

Change-Id: I4ac647406006c42004f9f5ab396cbf4e85688854
This commit is contained in:
Michael Sevakis 2012-05-11 02:39:15 -04:00
parent 0e5dd0a9cf
commit dd59e1d789
1 changed files with 38 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

41
lib/rbcodec/dsp/tdspeed.c
View file

@ -83,6 +83,37 @@ static const int buffer_sizes[NBUFFERS] =
/* Processed buffer passed out to later stages */
static struct dsp_buffer dsp_outbuf;
/* Blend overlapping frame samples according to position */
#if defined(CPU_COLDFIRE)
static inline int32_t blend_frame_samples(int32_t curr, int32_t prev,
int i, int j, int order)
{
int32_t a0, a1;
asm (
"mac.l %2, %3, %%acc0 \n" /* acc = curr*(i<<(30-order)) >> 23 */
"mac.l %4, %5, %%acc0 \n" /* acc += prev*(j<<(30-order)) >> 23 */
"moveq.l #1, %0 \n" /* Prepare mask */
"move.l %%accext01, %1 \n" /* Get extension bits */
"lsr.l #7, %1 \n" /* Get bit 7 of LSb extension ... */
"and.l %0, %1 \n" /* ... into bit 0 */
"movclr.l %%acc0, %0 \n" /* Get result >> 8 */
"asl.l #1, %0 \n" /* Everything x2 */
"or.l %1, %0 \n" /* Insert proper LSb from extension */
: "=d"(a0), "=d"(a1)
: "r"(curr), "r"(i << order),
"r"(prev), "r"(j << order));
return a0;
}
#else
/* Generic */
static inline int32_t blend_frame_samples(int32_t curr, int32_t prev,
int i, int j, int order)
{
return (curr * (int64_t)i + prev * (int64_t)j) >> order;
}
#endif /* CPU_* */
/* Discard all data */
static void tdspeed_flush(void)
{
@ -121,6 +152,11 @@ static bool tdspeed_update(int32_t samplerate, int32_t factor)
st->dst_order++;
st->dst_step = (1 << st->dst_order);
#ifdef CPU_COLDFIRE
/* blend_frame_samples works in s0.31 mode. Also must shift by
one less bit before mac in order not to overflow. */
st->dst_order = 30 - st->dst_order;
#endif
st->src_step = st->dst_step * factor / PITCH_SPEED_100;
st->shift_max = (st->dst_step > st->src_step) ?
st->dst_step : st->src_step;
@ -272,9 +308,8 @@ skip:;
for (int i = 0, j = st->dst_step; j; i++, j--)
{
assert(d < buf_out[ch] + out_size);
*d++ = (*curr++ * (int64_t)i +
*prev++ * (int64_t)j) >> st->dst_order;
*d++ = blend_frame_samples(*curr++, *prev++, i, j,
st->dst_order);
}
dest[ch] = d;