apps/fracmul.h

   1 #ifndef _FRACMUL_H
   2 #define _FRACMUL_H
   3
   4 /** FRACTIONAL MULTIPLICATION - TAKEN FROM apps/dsp.h
   5  *  Multiply two fixed point numbers with 31 fractional bits:
   6  *      FRACMUL(x, y)
   7  *
   8  *  Multiply two fixed point numbers with 31 fractional bits,
   9  *          then shift left by z bits:
  10  *      FRACMUL_SHL(x, y, z)
  11  *          NOTE: z must be in the range 1-8 on Coldfire targets.
  12  */
  13
  14
  15 /* A bunch of fixed point assembler helper macros */
  16 #if defined(CPU_COLDFIRE)
  17 /* These macros use the Coldfire EMAC extension and need the MACSR flags set
  18  * to fractional mode with no rounding.
  19  */
  20
  21 /* Multiply two S.31 fractional integers and return the sign bit and the
  22  * 31 most significant bits of the result.
  23  */
  24 #define FRACMUL(x, y) \
  25 ({ \
  26     long t; \
  27     asm ("mac.l    %[a], %[b], %%acc0\n\t" \
  28          "movclr.l %%acc0, %[t]\n\t" \
  29          : [t] "=r" (t) : [a] "r" (x), [b] "r" (y)); \
  30     t; \
  31 })
  32
  33 /* Multiply two S.31 fractional integers, and return the 32 most significant
  34  * bits after a shift left by the constant z. NOTE: Only works for shifts of
  35  * 1 to 8 on Coldfire!
  36  */
  37 #define FRACMUL_SHL(x, y, z) \
  38 ({ \
  39     long t, t2; \
  40     asm ("mac.l    %[a], %[b], %%acc0\n\t" \
  41          "moveq.l  %[d], %[t]\n\t" \
  42          "move.l   %%accext01, %[t2]\n\t" \
  43          "and.l    %[mask], %[t2]\n\t" \
  44          "lsr.l    %[t], %[t2]\n\t" \
  45          "movclr.l %%acc0, %[t]\n\t" \
  46          "asl.l    %[c], %[t]\n\t" \
  47          "or.l     %[t2], %[t]\n\t" \
  48          : [t] "=&d" (t), [t2] "=&d" (t2) \
  49          : [a] "r" (x), [b] "r" (y), [mask] "d" (0xff), \
  50            [c] "i" ((z)), [d] "i" (8 - (z))); \
  51     t; \
  52 })
  53
  54 #elif defined(CPU_ARM)
  55
  56 /* Multiply two S.31 fractional integers and return the sign bit and the
  57  * 31 most significant bits of the result.
  58  */
  59 #define FRACMUL(x, y) \
  60 ({ \
  61     long t, t2; \
  62     asm ("smull    %[t], %[t2], %[a], %[b]\n\t" \
  63          "mov      %[t2], %[t2], asl #1\n\t" \
  64          "orr      %[t], %[t2], %[t], lsr #31\n\t" \
  65          : [t] "=&r" (t), [t2] "=&r" (t2) \
  66          : [a] "r" (x), [b] "r" (y)); \
  67     t; \
  68 })
  69
  70 /* Multiply two S.31 fractional integers, and return the 32 most significant
  71  * bits after a shift left by the constant z.
  72  */
  73 #define FRACMUL_SHL(x, y, z) \
  74 ({ \
  75     long t, t2; \
  76     asm ("smull    %[t], %[t2], %[a], %[b]\n\t" \
  77          "mov      %[t2], %[t2], asl %[c]\n\t" \
  78          "orr      %[t], %[t2], %[t], lsr %[d]\n\t" \
  79          : [t] "=&r" (t), [t2] "=&r" (t2) \
  80          : [a] "r" (x), [b] "r" (y), \
  81            [c] "M" ((z) + 1), [d] "M" (31 - (z))); \
  82     t; \
  83 })
  84
  85 #else
  86
  87 #define FRACMUL(x, y) (long) (((((long long) (x)) * ((long long) (y))) >> 31))
  88 #define FRACMUL_SHL(x, y, z) \
  89 ((long)(((((long long) (x)) * ((long long) (y))) >> (31 - (z)))))
  90
  91 #endif
  92
  93 #endif