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Another minor ARM speedup for libwmapro. Drop lsb of multiplication result in fixmul31(). The difference to current implementation is +/-1 in the output signal. Same routines are used for other codecs and in the codec lib as well.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@27728 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Andree Buschmann 2010-08-05 21:59:29 +00:00
parent cc7fac27b5
commit 4b49ef2ade
1 changed files with 3 additions and 4 deletions
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7
apps/codecs/libwmapro/wmapro_math.h
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@ -53,18 +53,17 @@
lo; \
})
/* Calculates: result = (X*Y)>>31 */
/* Calculates: result = (X*Y)>>31, loose 1 bit precision */
#define fixmul31(X,Y) \
({ \
int32_t lo; \
int32_t hi; \
asm volatile ( \
"smull %[lo], %[hi], %[x], %[y] \n\t" /* multiply */ \
"mov %[lo], %[lo], lsr #31 \n\t" /* lo >>= 31 */ \
"orr %[lo], %[lo], %[hi], lsl #1" /* lo |= (hi << 1) */ \
"mov %[hi], %[hi], lsl #1" /* hi <<= 1 */ \
: [lo]"=&r"(lo), [hi]"=&r"(hi) \
: [x]"r"(X), [y]"r"(Y)); \
lo; \
hi; \
})
#elif defined(CPU_COLDFIRE)
/* Calculates: result = (X*Y)>>Z */