src/audio/SDL_mixer.c
author Sam Lantinga <slouken@libsdl.org>
Sun, 28 May 2006 13:04:16 +0000
branchSDL-1.3
changeset 1662 782fd950bd46
parent 1442 e3242177fe4a
child 1668 4da1ee79c9af
permissions -rw-r--r--
Revamp of the video system in progress - adding support for multiple displays, multiple windows, and a full video mode selection API.

WARNING: None of the video drivers have been updated for the new API yet! The API is still under design and very fluid.

The code is now run through a consistent indent format:
indent -i4 -nut -nsc -br -ce

The headers are being converted to automatically generate doxygen documentation.
     1 /*
     2     SDL - Simple DirectMedia Layer
     3     Copyright (C) 1997-2006 Sam Lantinga
     4 
     5     This library is free software; you can redistribute it and/or
     6     modify it under the terms of the GNU Lesser General Public
     7     License as published by the Free Software Foundation; either
     8     version 2.1 of the License, or (at your option) any later version.
     9 
    10     This library is distributed in the hope that it will be useful,
    11     but WITHOUT ANY WARRANTY; without even the implied warranty of
    12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    13     Lesser General Public License for more details.
    14 
    15     You should have received a copy of the GNU Lesser General Public
    16     License along with this library; if not, write to the Free Software
    17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
    18 
    19     Sam Lantinga
    20     slouken@libsdl.org
    21 */
    22 #include "SDL_config.h"
    23 
    24 /* This provides the default mixing callback for the SDL audio routines */
    25 
    26 #include "SDL_cpuinfo.h"
    27 #include "SDL_timer.h"
    28 #include "SDL_audio.h"
    29 #include "SDL_sysaudio.h"
    30 #include "SDL_mixer_MMX.h"
    31 #include "SDL_mixer_MMX_VC.h"
    32 #include "SDL_mixer_m68k.h"
    33 
    34 /* This table is used to add two sound values together and pin
    35  * the value to avoid overflow.  (used with permission from ARDI)
    36  * Changed to use 0xFE instead of 0xFF for better sound quality.
    37  */
    38 static const Uint8 mix8[] = {
    39     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    40     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    41     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    42     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    43     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    44     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    45     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    46     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    47     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    48     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    49     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    50     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x03,
    51     0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E,
    52     0x0F, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19,
    53     0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, 0x23, 0x24,
    54     0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F,
    55     0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A,
    56     0x3B, 0x3C, 0x3D, 0x3E, 0x3F, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45,
    57     0x46, 0x47, 0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F, 0x50,
    58     0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5A, 0x5B,
    59     0x5C, 0x5D, 0x5E, 0x5F, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66,
    60     0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70, 0x71,
    61     0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C,
    62     0x7D, 0x7E, 0x7F, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
    63     0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8F, 0x90, 0x91, 0x92,
    64     0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0x9B, 0x9C, 0x9D,
    65     0x9E, 0x9F, 0xA0, 0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8,
    66     0xA9, 0xAA, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF, 0xB0, 0xB1, 0xB2, 0xB3,
    67     0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE,
    68     0xBF, 0xC0, 0xC1, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7, 0xC8, 0xC9,
    69     0xCA, 0xCB, 0xCC, 0xCD, 0xCE, 0xCF, 0xD0, 0xD1, 0xD2, 0xD3, 0xD4,
    70     0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA, 0xDB, 0xDC, 0xDD, 0xDE, 0xDF,
    71     0xE0, 0xE1, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA,
    72     0xEB, 0xEC, 0xED, 0xEE, 0xEF, 0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5,
    73     0xF6, 0xF7, 0xF8, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE, 0xFE, 0xFE,
    74     0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    75     0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    76     0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    77     0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    78     0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    79     0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    80     0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    81     0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    82     0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    83     0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    84     0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    85     0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE
    86 };
    87 
    88 /* The volume ranges from 0 - 128 */
    89 #define ADJUST_VOLUME(s, v)	(s = (s*v)/SDL_MIX_MAXVOLUME)
    90 #define ADJUST_VOLUME_U8(s, v)	(s = (((s-128)*v)/SDL_MIX_MAXVOLUME)+128)
    91 
    92 void
    93 SDL_MixAudio (Uint8 * dst, const Uint8 * src, Uint32 len, int volume)
    94 {
    95     Uint16 format;
    96 
    97     if (volume == 0) {
    98         return;
    99     }
   100     /* Mix the user-level audio format */
   101     if (current_audio) {
   102         if (current_audio->convert.needed) {
   103             format = current_audio->convert.src_format;
   104         } else {
   105             format = current_audio->spec.format;
   106         }
   107     } else {
   108         /* HACK HACK HACK */
   109         format = AUDIO_S16;
   110     }
   111     switch (format) {
   112 
   113     case AUDIO_U8:
   114         {
   115 #if defined(__GNUC__) && defined(__M68000__) && defined(SDL_ASSEMBLY_ROUTINES)
   116             SDL_MixAudio_m68k_U8 ((char *) dst, (char *) src,
   117                                   (unsigned long) len, (long) volume,
   118                                   (char *) mix8);
   119 #else
   120             Uint8 src_sample;
   121 
   122             while (len--) {
   123                 src_sample = *src;
   124                 ADJUST_VOLUME_U8 (src_sample, volume);
   125                 *dst = mix8[*dst + src_sample];
   126                 ++dst;
   127                 ++src;
   128             }
   129 #endif
   130         }
   131         break;
   132 
   133     case AUDIO_S8:
   134         {
   135 #if defined(__GNUC__) && defined(__i386__) && defined(SDL_ASSEMBLY_ROUTINES)
   136             if (SDL_HasMMX ()) {
   137                 SDL_MixAudio_MMX_S8 ((char *) dst, (char *) src,
   138                                      (unsigned int) len, (int) volume);
   139             } else
   140 #elif ((defined(_MSC_VER) && defined(_M_IX86)) || defined(__WATCOMC__)) && defined(SDL_ASSEMBLY_ROUTINES)
   141             if (SDL_HasMMX ()) {
   142                 SDL_MixAudio_MMX_S8_VC ((char *) dst, (char *) src,
   143                                         (unsigned int) len, (int) volume);
   144             } else
   145 #endif
   146 #if defined(__GNUC__) && defined(__M68000__) && defined(SDL_ASSEMBLY_ROUTINES)
   147                 SDL_MixAudio_m68k_S8 ((char *) dst, (char *) src,
   148                                       (unsigned long) len, (long) volume);
   149 #else
   150             {
   151                 Sint8 *dst8, *src8;
   152                 Sint8 src_sample;
   153                 int dst_sample;
   154                 const int max_audioval = ((1 << (8 - 1)) - 1);
   155                 const int min_audioval = -(1 << (8 - 1));
   156 
   157                 src8 = (Sint8 *) src;
   158                 dst8 = (Sint8 *) dst;
   159                 while (len--) {
   160                     src_sample = *src8;
   161                     ADJUST_VOLUME (src_sample, volume);
   162                     dst_sample = *dst8 + src_sample;
   163                     if (dst_sample > max_audioval) {
   164                         *dst8 = max_audioval;
   165                     } else if (dst_sample < min_audioval) {
   166                         *dst8 = min_audioval;
   167                     } else {
   168                         *dst8 = dst_sample;
   169                     }
   170                     ++dst8;
   171                     ++src8;
   172                 }
   173             }
   174 #endif
   175         }
   176         break;
   177 
   178     case AUDIO_S16LSB:
   179         {
   180 #if defined(__GNUC__) && defined(__i386__) && defined(SDL_ASSEMBLY_ROUTINES)
   181             if (SDL_HasMMX ()) {
   182                 SDL_MixAudio_MMX_S16 ((char *) dst, (char *) src,
   183                                       (unsigned int) len, (int) volume);
   184             } else
   185 #elif ((defined(_MSC_VER) && defined(_M_IX86)) || defined(__WATCOMC__)) && defined(SDL_ASSEMBLY_ROUTINES)
   186             if (SDL_HasMMX ()) {
   187                 SDL_MixAudio_MMX_S16_VC ((char *) dst, (char *) src,
   188                                          (unsigned int) len, (int) volume);
   189             } else
   190 #endif
   191 #if defined(__GNUC__) && defined(__M68000__) && defined(SDL_ASSEMBLY_ROUTINES)
   192                 SDL_MixAudio_m68k_S16LSB ((short *) dst, (short *) src,
   193                                           (unsigned long) len, (long) volume);
   194 #else
   195             {
   196                 Sint16 src1, src2;
   197                 int dst_sample;
   198                 const int max_audioval = ((1 << (16 - 1)) - 1);
   199                 const int min_audioval = -(1 << (16 - 1));
   200 
   201                 len /= 2;
   202                 while (len--) {
   203                     src1 = ((src[1]) << 8 | src[0]);
   204                     ADJUST_VOLUME (src1, volume);
   205                     src2 = ((dst[1]) << 8 | dst[0]);
   206                     src += 2;
   207                     dst_sample = src1 + src2;
   208                     if (dst_sample > max_audioval) {
   209                         dst_sample = max_audioval;
   210                     } else if (dst_sample < min_audioval) {
   211                         dst_sample = min_audioval;
   212                     }
   213                     dst[0] = dst_sample & 0xFF;
   214                     dst_sample >>= 8;
   215                     dst[1] = dst_sample & 0xFF;
   216                     dst += 2;
   217                 }
   218             }
   219 #endif
   220         }
   221         break;
   222 
   223     case AUDIO_S16MSB:
   224         {
   225 #if defined(__GNUC__) && defined(__M68000__) && defined(SDL_ASSEMBLY_ROUTINES)
   226             SDL_MixAudio_m68k_S16MSB ((short *) dst, (short *) src,
   227                                       (unsigned long) len, (long) volume);
   228 #else
   229             Sint16 src1, src2;
   230             int dst_sample;
   231             const int max_audioval = ((1 << (16 - 1)) - 1);
   232             const int min_audioval = -(1 << (16 - 1));
   233 
   234             len /= 2;
   235             while (len--) {
   236                 src1 = ((src[0]) << 8 | src[1]);
   237                 ADJUST_VOLUME (src1, volume);
   238                 src2 = ((dst[0]) << 8 | dst[1]);
   239                 src += 2;
   240                 dst_sample = src1 + src2;
   241                 if (dst_sample > max_audioval) {
   242                     dst_sample = max_audioval;
   243                 } else if (dst_sample < min_audioval) {
   244                     dst_sample = min_audioval;
   245                 }
   246                 dst[1] = dst_sample & 0xFF;
   247                 dst_sample >>= 8;
   248                 dst[0] = dst_sample & 0xFF;
   249                 dst += 2;
   250             }
   251 #endif
   252         }
   253         break;
   254 
   255     default:                   /* If this happens... FIXME! */
   256         SDL_SetError ("SDL_MixAudio(): unknown audio format");
   257         return;
   258     }
   259 }
   260 
   261 /* vi: set ts=4 sw=4 expandtab: */