apps/codecs/libatrac/fixp_math.h

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2009 Mohamed Tarek
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21 #include <stdlib.h>
  22 #include <inttypes.h>
  23
  24 /* Macros for converting between various fixed-point representations and floating point. */
  25 #define ONE_16 (1L << 16)
  26 #define fixtof64(x)       (float)((float)(x) / (float)(1 << 16))        //does not work on int64_t!
  27 #define ftofix32(x)       ((int32_t)((x) * (float)(1 << 16) + ((x) < 0 ? -0.5 : 0.5)))
  28 #define ftofix31(x)       ((int32_t)((x) * (float)(1 << 31) + ((x) < 0 ? -0.5 : 0.5)))
  29 #define fix31tof64(x)     (float)((float)(x) / (float)(1 << 31))
  30
  31 /* Fixed point math routines for use in atrac3.c */
  32
  33 #if defined(CPU_ARM)
  34     /* Calculates: result = (X*Y)>>16 */
  35     #define fixmul16(X,Y) \
  36      ({ \
  37         int32_t lo; \
  38         int32_t hi; \
  39         asm volatile ( \
  40            "smull %[lo], %[hi], %[x], %[y] \n\t" /* multiply */ \
  41            "mov   %[lo], %[lo], lsr #16    \n\t" /* lo >>= 16 */ \
  42            "orr   %[lo], %[lo], %[hi], lsl #16"  /* lo |= (hi << 16) */ \
  43            : [lo]"=&r"(lo), [hi]"=&r"(hi) \
  44            : [x]"r"(X), [y]"r"(Y)); \
  45         lo; \
  46      })
  47
  48     /* Calculates: result = (X*Y)>>31 */
  49     /* Use scratch register r12 */
  50     #define fixmul31(X,Y) \
  51      ({ \
  52         int32_t lo; \
  53         int32_t hi; \
  54         asm volatile ( \
  55            "smull %[lo], %[hi], %[x], %[y] \n\t" /* multiply */ \
  56            "mov   %[lo], %[lo], lsr #31    \n\t" /* lo >>= 31 */ \
  57            "orr   %[lo], %[lo], %[hi], lsl #1"   /* lo |= (hi << 1) */ \
  58            : [lo]"=&r"(lo), [hi]"=&r"(hi) \
  59            : [x]"r"(X), [y]"r"(Y)); \
  60         lo; \
  61      })
  62 #elif defined(CPU_COLDFIRE)
  63     /* Calculates: result = (X*Y)>>16 */
  64     #define fixmul16(X,Y) \
  65     ({ \
  66         int32_t t, x = (X); \
  67         asm volatile ( \
  68             "mac.l    %[x],%[y],%%acc0\n\t" /* multiply */ \
  69             "mulu.l   %[y],%[x]       \n\t" /* get lower half, avoid emac stall */ \
  70             "movclr.l %%acc0,%[t]     \n\t" /* get higher half */ \
  71             "lsr.l    #1,%[t]         \n\t" /* hi >>= 1 to compensate emac shift */ \
  72             "move.w   %[t],%[x]       \n\t" /* combine halfwords */\
  73             "swap     %[x]            \n\t" \
  74             : [t]"=&d"(t), [x] "+d" (x) \
  75             : [y] "d" ((Y))); \
  76         x; \
  77     })
  78
  79     #define fixmul31(X,Y) \
  80     ({ \
  81        int32_t t; \
  82        asm volatile ( \
  83           "mac.l %[x], %[y], %%acc0\n\t"   /* multiply */ \
  84           "movclr.l %%acc0, %[t]\n\t"      /* get higher half as result */ \
  85           : [t] "=d" (t) \
  86           : [x] "r" ((X)), [y] "r" ((Y))); \
  87        t; \
  88     })
  89 #else
  90     static inline int32_t fixmul16(int32_t x, int32_t y)
  91     {
  92         int64_t temp;
  93         temp = x;
  94         temp *= y;
  95
  96         temp >>= 16;
  97
  98         return (int32_t)temp;
  99     }
 100
 101     static inline int32_t fixmul31(int32_t x, int32_t y)
 102     {
 103         int64_t temp;
 104         temp = x;
 105         temp *= y;
 106
 107         temp >>= 31;        //16+31-16 = 31 bits
 108
 109         return (int32_t)temp;
 110     }
 111 #endif