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SPC codec on Coldfire: Move movclrs into the light and out of the long dark shadow cast my emac latency as much as possible. Put in a faster interpolation routine (emac saves the day...again). Add comments about what's going on.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@12558 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Michael Sevakis 2007-03-03 01:19:35 +00:00
parent 55aabe34ca
commit f2b6ecd5fe
1 changed files with 62 additions and 31 deletions
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93
apps/codecs/spc/Spc_Dsp.h
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@ -974,23 +974,35 @@ static void DSP_run_( struct Spc_Dsp* this, long count, int32_t* out_buf )
if ( (this->r.g.noise_enables & vbit) == 0 )
{
uint32_t f = voice->position;
int32_t y1;
int32_t y0;
/**
* Formula (fastest found so far of MANY):
* output = y0 + f*y1 - f*y0
*/
asm volatile (
"move.l %[f], %[y0] \r\n" /* separate fraction */
"and.l #0xfff, %[f] \r\n" /* and whole parts */
"lsr.l %[sh], %[y0] \r\n"
"move.l 2(%[s], %[y0].l*2), %[y1] \r\n" /* load two samples */
"move.l %[y1], %[y0] \r\n" /* separate samples */
"ext.l %[y1] \r\n" /* y0=s[1], y1=s[2] */
"swap %[y0] \r\n"
"ext.l %[y0] \r\n"
"sub.l %[y0], %[y1] \r\n" /* diff = y1 - y0 */
"muls.l %[f], %[y1] \r\n" /* y0 += f*diff */
"asr.l %[sh], %[y1] \r\n"
"add.l %[y1], %[y0] \r\n"
: [f]"+&d"(f), [y0]"=&d"(output), [y1]"=&d"(y1)
: [s]"a"(voice->samples), [sh]"r"(12)
/* separate fractional and whole parts */
"move.l %[f], %[y1] \r\n"
"and.l #0xfff, %[f] \r\n"
"lsr.l %[sh], %[y1] \r\n"
/* load samples y0 (upper) & y1 (lower) */
"move.l 2(%[s], %[y1].l*2), %[y1] \r\n"
/* %acc0 = f*y1 */
"mac.w %[f]l, %[y1]l, %%acc0 \r\n"
/* msac.w is 2% boostier so add negative */
"neg.l %[f] \r\n"
/* %acc0 -= f*y0 */
"mac.w %[f]l, %[y1]u, %%acc0 \r\n"
/* separate out y0 and sign extend */
"swap %[y1] \r\n"
"movea.w %[y1], %[y0] \r\n"
/* fetch result, scale down and add y0 */
"movclr.l %%acc0, %[y1] \r\n"
/* output = y0 + (result >> 12) */
"asr.l %[sh], %[y1] \r\n"
"add.l %[y0], %[y1] \r\n"
: [f]"+&d"(f), [y0]"=&a"(y0), [y1]"=&d"(output)
: [s]"a"(voice->samples), [sh]"d"(12)
);
}
@ -1093,9 +1105,13 @@ static void DSP_run_( struct Spc_Dsp* this, long count, int32_t* out_buf )
*this->last_fir_ptr = fb;
this->last_fir_ptr = this->fir_ptr;
/* Apply echo FIR filter to output - circular buffer is hardware
incremented and masked; FIR coefficients and buffer history are
loaded in parallel with multiply accumulate operations. */
/* Apply echo FIR filter to output samples read from echo buffer -
circular buffer is hardware incremented and masked; FIR
coefficients and buffer history are loaded in parallel with
multiply accumulate operations. Shift left by one here and once
again when calculating feedback to have sample values justified
to bit 31 in the output to ease endian swap, interleaving and
clamping before placing result in the program's echo buffer. */
int _0, _1, _2;
asm volatile (
"move.l (%[fir_c]) , %[_2] \r\n"
@ -1115,53 +1131,68 @@ static void DSP_run_( struct Spc_Dsp* this, long count, int32_t* out_buf )
"mac.w %[_1]l, %[_2]u, << , %%acc1 \r\n"
"mac.w %[_0]u, %[_2]l, << , %%acc0 \r\n"
"mac.w %[_0]l, %[_2]l, << , %%acc1 \r\n"
"movclr.l %%acc0, %[out_0] \r\n"
"movclr.l %%acc1, %[out_1] \r\n"
: [_0]"=&r"(_0), [_1]"=&r"(_1), [_2]"=&r"(_2),
[fir_p]"+a"(this->fir_ptr),
[out_0]"=r"(out_0), [out_1]"=r"(out_1)
[fir_p]"+a"(this->fir_ptr)
: [fir_c]"a"(this->fir_coeff), [fb]"r"(fb)
);
/* Generate output */
asm volatile (
/* fetch filter results to eliminate stalls */
"movclr.l %%acc0, %[out_0] \r\n"
"movclr.l %%acc1, %[out_1] \r\n"
/* apply global volume */
"mac.l %[chans_0], %[gv_0] , %%acc2 \r\n"
"mac.l %[chans_1], %[gv_1] , %%acc3 \r\n"
/* apply echo volume and add to final output */
"mac.l %[ev_0], %[out_0], >>, %%acc2 \r\n"
"mac.l %[ev_1], %[out_1], >>, %%acc3 \r\n"
:
: [out_0]"=&r"(out_0), [out_1]"=&r"(out_1)
: [chans_0]"r"(chans_0), [gv_0]"r"(global_vol_0),
[ev_0]"r"((int)this->r.g.echo_volume_0),
[chans_1]"r"(chans_1), [gv_1]"r"(global_vol_1),
[ev_1]"r"((int)this->r.g.echo_volume_1),
[out_0]"r"(out_0), [out_1]"r"(out_1)
[ev_1]"r"((int)this->r.g.echo_volume_1)
);
/* Feedback into echo buffer */
if ( !(this->r.g.flags & 0x20) )
{
asm volatile (
"mac.l %[sh], %[e0] , %%acc0 \r\n"
"mac.l %[out_0], %[ef], <<, %%acc0 \r\n"
/* scale echo voices; saturate if overflow */
"mac.l %[sh], %[e1] , %%acc1 \r\n"
"mac.l %[sh], %[e0] , %%acc0 \r\n"
/* add scaled output from FIR filter */
"mac.l %[out_1], %[ef], <<, %%acc1 \r\n"
"movclr.l %%acc0, %[e0] \r\n"
"mac.l %[out_0], %[ef], <<, %%acc0 \r\n"
/* swap and fetch feedback results - simply
swap_odd_even32 mixed in between macs and
movclrs to mitigate stall issues */
"move.l #0x00ff00ff, %[sh] \r\n"
"movclr.l %%acc1, %[e1] \r\n"
"swap %[e1] \r\n"
"movclr.l %%acc0, %[e0] \r\n"
"move.w %[e1], %[e0] \r\n"
"and.l %[e0], %[sh] \r\n"
"eor.l %[sh], %[e0] \r\n"
"lsl.l #8, %[sh] \r\n"
"lsr.l #8, %[e0] \r\n"
"or.l %[sh], %[e0] \r\n"
/* save final feedback into echo buffer */
"move.l %[e0], (%[echo_ptr]) \r\n"
: [e0]"+&d"(echo_0), [e1]"+&d"(echo_1)
: [out_0]"r"(out_0), [out_1]"r"(out_1),
[ef]"r"((int)this->r.g.echo_feedback),
[sh]"r"(1 << 9)
[echo_ptr]"a"((int32_t *)echo_ptr),
[sh]"d"(1 << 9)
);
*(int32_t *)echo_ptr = swap_odd_even32(echo_0);
}
/* Output final samples */
asm volatile (
/* fetch output saved in %acc2 and %acc3 */
"movclr.l %%acc2, %[out_0] \r\n"
"movclr.l %%acc3, %[out_1] \r\n"
/* scale right by global_muting shift */
"asr.l %[gm], %[out_0] \r\n"
"asr.l %[gm], %[out_1] \r\n"
: [out_0]"=&d"(out_0), [out_1]"=&d"(out_1)