FreeBSD/Linux Kernel Cross Reference
sys/tools/sound/snd_fxdiv_gen.awk

     #!/usr/bin/awk -f
     #
     # SPDX-License-Identifier: BSD-2-Clause-FreeBSD
     #
     # Copyright (c) 2008-2009 Ariff Abdullah <ariff@FreeBSD.org>
     # All rights reserved.
     #
     # Redistribution and use in source and binary forms, with or without
     # modification, are permitted provided that the following conditions
    # are met:
    # 1. Redistributions of source code must retain the above copyright
    #    notice, this list of conditions and the following disclaimer.
    # 2. Redistributions in binary form must reproduce the above copyright
    #    notice, this list of conditions and the following disclaimer in the
    #    documentation and/or other materials provided with the distribution.
    #
    # THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
    # ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
    # ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
    # FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
    # DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
    # OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
    # HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
    # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
    # OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
    # SUCH DAMAGE.
    #
    # $FreeBSD$
    #
    
    function floor(x, r)
    {
            r = int(x);
            if (r > x)
                    r--;
            return (r + 0);
    }
    
    function shl(x, y)
    {
            while (y > 0) {
                    x *= 2;
                    y--;
            }
            return (x);
    }
    
    function shr(x, y)
    {
            while (y > 0 && x != 0) {
                    x = floor(x / 2);
                    y--;
            }
            return (x);
    }
    
    function calcdiv(r, x, y, z)
    {
            y = floor(FXONE / x);
            z = FXSHIFT;
    
            while (shr((y * x), z) < 1)
                    y++;
    
            while ((y % 2) == 0 && z > 0) {
                    y = floor(y / 2);
                    z--;
            }
    
            r["mul"] = y;
            r["shift"] = z;
    }
    
    BEGIN {
            FXSHIFT = 16;
            FXONE   = shl(1, FXSHIFT);
    
            SND_CHN_MAX = 127;
    
            PCM_8_BPS  = 1;
            PCM_16_BPS = 2;
            PCM_24_BPS = 3;
            PCM_32_BPS = 4;
    
            SND_MAX_ALIGN = SND_CHN_MAX * PCM_32_BPS;
    
            for (i = 1; i <= SND_CHN_MAX; i++) {
                    aligns[PCM_8_BPS * i]  = 1;
                    aligns[PCM_16_BPS * i] = 1;
                    aligns[PCM_24_BPS * i] = 1;
                    aligns[PCM_32_BPS * i] = 1;
            }
    
            printf("#ifndef _SND_FXDIV_GEN_H_\n");
            printf("#define _SND_FXDIV_GEN_H_\n\n");
    
            printf("/*\n");
            printf(" * Generated using snd_fxdiv_gen.awk, heaven, wind and awesome.\n");
           printf(" *\n");
           printf(" * DO NOT EDIT!\n");
           printf(" */\n\n");
           printf("#ifdef SND_USE_FXDIV\n\n");
   
           printf("/*\n");
           printf(" * Fast unsigned 32bit integer division and rounding, accurate for\n");
           printf(" * x = 1 - %d. This table should be enough to handle possible\n", FXONE);
           printf(" * division for 1 - 508 (more can be generated though..).\n");
           printf(" *\n");
           printf(" * 508 = SND_CHN_MAX * PCM_32_BPS, which is why....\n");
           printf(" */\n\n");
   
           printf("extern const uint32_t snd_fxdiv_table[%d][2];\n\n", SND_MAX_ALIGN + 1);
   
           printf("#ifdef SND_DECLARE_FXDIV\n");
           printf("const uint32_t snd_fxdiv_table[%d][2] = {\n", SND_MAX_ALIGN + 1);
   
           for (i = 1; i <= SND_MAX_ALIGN; i++) {
                   if (aligns[i] != 1)
                           continue;
                   calcdiv(r, i);
                   printf("\t[0x%02x] = { 0x%04x, 0x%02x },",              \
                       i, r["mul"], r["shift"]);
                   printf("\t/* x / %-2d = (x * %-5d) >> %-2d */\n",       \
                       i, r["mul"], r["shift"]);
           }
   
           printf("};\n#endif\n\n");
   
           printf("#define SND_FXDIV_MAX\t\t0x%08x\n", FXONE);
           printf("#define SND_FXDIV(x, y)\t\t(((uint32_t)(x) *\t\t\t\\\n");
           printf("\t\t\t\t    snd_fxdiv_table[y][0]) >>\t\t\\\n");
           printf("\t\t\t\t    snd_fxdiv_table[y][1])\n");
           printf("#define SND_FXROUND(x, y)\t(SND_FXDIV(x, y) * (y))\n");
           printf("#define SND_FXMOD(x, y)\t\t((x) - SND_FXROUND(x, y))\n\n");
   
           printf("#else\t/* !SND_USE_FXDIV */\n\n");
   
           printf("#define SND_FXDIV_MAX\t\t0x%08x\n", 131072);
           printf("#define SND_FXDIV(x, y)\t\t((x) / (y))\n");
           printf("#define SND_FXROUND(x, y)\t((x) - ((x) %% (y)))\n");
           printf("#define SND_FXMOD(x, y)\t\t((x) %% (y))\n\n");
   
           printf("#endif\t/* SND_USE_FXDIV */\n\n");
   
           printf("#endif\t/* !_SND_FXDIV_GEN_H_ */\n");
   }

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