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pcm as3525v1: revert 26761 to use faster ASM code

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Fix the asm constraints to mark the left output variable as earlyclobber
Thanks to amiconn

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@26777 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Rafaël Carré 2010-06-11 14:04:48 +00:00
parent 9a2b1d612c
commit d5a27c2fb1
1 changed files with 14 additions and 1 deletions
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15
firmware/target/arm/as3525/pcm-as3525.c
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@ -263,7 +263,7 @@ static inline void mono2stereo(int16_t *end)
{ {
if(audio_channels != 1) /* only for microphone */ if(audio_channels != 1) /* only for microphone */
return; return;
#if 0
/* load pointer in a register and avoid updating it in each loop */ /* load pointer in a register and avoid updating it in each loop */
register int16_t *samples = mono_samples; register int16_t *samples = mono_samples;
@ -273,6 +273,19 @@ static inline void mono2stereo(int16_t *end)
} while(samples != end); } while(samples != end);
mono_samples = samples; /* update pointer */ mono_samples = samples; /* update pointer */
#else
/* gcc doesn't use pre indexing : let's save 1 cycle */
int16_t left;
asm (
"1: ldrh %0, [%1], #2 \n" // load 1 sample of the left-channel
" strh %0, [%1], #2 \n" // copy it in the right-channel
" cmp %1, %2 \n" // are we finished?
" bne 1b \n"
: "=&r"(left), "+r"(mono_samples)
: "r"(end)
: "memory"
);
#endif /* C / ASM */
} }
#endif /* CONFIG_CPU == AS3525 */ #endif /* CONFIG_CPU == AS3525 */