103 lines
2.8 KiB
C
103 lines
2.8 KiB
C
#ifndef _FRACMUL_H
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#define _FRACMUL_H
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#include <stdint.h>
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#include "gcc_extensions.h"
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/** FRACTIONAL MULTIPLICATION
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* Multiply two fixed point numbers with 31 fractional bits:
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* FRACMUL(x, y)
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*
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* Multiply two fixed point numbers with 31 fractional bits,
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* then shift left by z bits:
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* FRACMUL_SHL(x, y, z)
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* NOTE: z must be in the range 1-8 on Coldfire targets.
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*/
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/* A bunch of fixed point assembler helper macros */
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#if defined(CPU_COLDFIRE)
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/* These macros use the Coldfire EMAC extension and need the MACSR flags set
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* to fractional mode with no rounding.
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*/
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/* Multiply two S.31 fractional integers and return the sign bit and the
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* 31 most significant bits of the result.
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*/
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static inline int32_t FRACMUL(int32_t x, int32_t y)
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{
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int32_t t;
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asm ("mac.l %[a], %[b], %%acc0\n\t"
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"movclr.l %%acc0, %[t]\n\t"
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: [t] "=r" (t) : [a] "r" (x), [b] "r" (y));
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return t;
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}
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/* Multiply two S.31 fractional integers, and return the 32 most significant
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* bits after a shift left by the constant z. NOTE: Only works for shifts of
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* 1 to 8 on Coldfire!
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*/
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static FORCE_INLINE int32_t FRACMUL_SHL(int32_t x, int32_t y, int z)
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{
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int32_t t, t2;
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asm ("mac.l %[a], %[b], %%acc0\n\t"
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"move.l %[d], %[t]\n\t"
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"move.l %%accext01, %[t2]\n\t"
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"and.l %[mask], %[t2]\n\t"
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"lsr.l %[t], %[t2]\n\t"
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"movclr.l %%acc0, %[t]\n\t"
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"asl.l %[c], %[t]\n\t"
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"or.l %[t2], %[t]\n\t"
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: [t] "=&d" (t), [t2] "=&d" (t2)
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: [a] "r" (x), [b] "r" (y), [mask] "d" (0xff),
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[c] "id" ((z)), [d] "id" (8 - (z)));
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return t;
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}
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#elif defined(CPU_ARM)
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/* Multiply two S.31 fractional integers and return the sign bit and the
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* 31 most significant bits of the result.
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*/
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static inline int32_t FRACMUL(int32_t x, int32_t y)
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{
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int32_t t, t2;
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asm ("smull %[t], %[t2], %[a], %[b]\n\t"
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"mov %[t2], %[t2], asl #1\n\t"
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"orr %[t], %[t2], %[t], lsr #31\n\t"
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: [t] "=&r" (t), [t2] "=&r" (t2)
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: [a] "r" (x), [b] "r" (y));
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return t;
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}
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/* Multiply two S.31 fractional integers, and return the 32 most significant
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* bits after a shift left by the constant z.
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*/
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static FORCE_INLINE int32_t FRACMUL_SHL(int32_t x, int32_t y, int z)
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{
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int32_t t, t2;
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asm ("smull %[t], %[t2], %[a], %[b]\n\t"
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"mov %[t2], %[t2], asl %[c]\n\t"
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"orr %[t], %[t2], %[t], lsr %[d]\n\t"
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: [t] "=&r" (t), [t2] "=&r" (t2)
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: [a] "r" (x), [b] "r" (y),
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[c] "Mr" ((z) + 1), [d] "Mr" (31 - (z)));
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return t;
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}
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#else
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static inline int32_t FRACMUL(int32_t x, int32_t y)
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{
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return (int32_t) (((int64_t)x * y) >> 31);
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}
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static inline int32_t FRACMUL_SHL(int32_t x, int32_t y, int z)
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{
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return (int32_t) (((int64_t)x * y) >> (31 - z));
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}
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#endif
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#endif
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