src/audio/SDL_mixer.c
author Sam Lantinga
Mon, 06 Feb 2006 08:28:51 +0000
changeset 1330 450721ad5436
parent 1312 c9b51268668f
child 1358 c71e05b4dc2e
permissions -rw-r--r--
It's now possible to build SDL without any C runtime at all on Windows,
using Visual C++ 2005
     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 
    23 /* This provides the default mixing callback for the SDL audio routines */
    24 
    25 #include "SDL_audio.h"
    26 #include "SDL_mutex.h"
    27 #include "SDL_timer.h"
    28 #include "SDL_cpuinfo.h"
    29 #include "SDL_sysaudio.h"
    30 #include "SDL_cpuinfo.h"
    31 #include "SDL_mixer_MMX.h"
    32 #include "SDL_mixer_MMX_VC.h"
    33 #include "SDL_mixer_m68k.h"
    34 
    35 /* This table is used to add two sound values together and pin
    36  * the value to avoid overflow.  (used with permission from ARDI)
    37  * Changed to use 0xFE instead of 0xFF for better sound quality.
    38  */
    39 static const Uint8 mix8[] =
    40 {
    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, 0x00, 0x00, 0x00,
    51   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    52   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x03,
    53   0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E,
    54   0x0F, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19,
    55   0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, 0x23, 0x24,
    56   0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F,
    57   0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A,
    58   0x3B, 0x3C, 0x3D, 0x3E, 0x3F, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45,
    59   0x46, 0x47, 0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F, 0x50,
    60   0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5A, 0x5B,
    61   0x5C, 0x5D, 0x5E, 0x5F, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66,
    62   0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70, 0x71,
    63   0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C,
    64   0x7D, 0x7E, 0x7F, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
    65   0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8F, 0x90, 0x91, 0x92,
    66   0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0x9B, 0x9C, 0x9D,
    67   0x9E, 0x9F, 0xA0, 0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8,
    68   0xA9, 0xAA, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF, 0xB0, 0xB1, 0xB2, 0xB3,
    69   0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE,
    70   0xBF, 0xC0, 0xC1, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7, 0xC8, 0xC9,
    71   0xCA, 0xCB, 0xCC, 0xCD, 0xCE, 0xCF, 0xD0, 0xD1, 0xD2, 0xD3, 0xD4,
    72   0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA, 0xDB, 0xDC, 0xDD, 0xDE, 0xDF,
    73   0xE0, 0xE1, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA,
    74   0xEB, 0xEC, 0xED, 0xEE, 0xEF, 0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5,
    75   0xF6, 0xF7, 0xF8, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 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, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    86   0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    87   0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE
    88 };
    89 
    90 /* The volume ranges from 0 - 128 */
    91 #define ADJUST_VOLUME(s, v)	(s = (s*v)/SDL_MIX_MAXVOLUME)
    92 #define ADJUST_VOLUME_U8(s, v)	(s = (((s-128)*v)/SDL_MIX_MAXVOLUME)+128)
    93 
    94 void SDL_MixAudio (Uint8 *dst, const Uint8 *src, Uint32 len, int volume)
    95 {
    96 	Uint16 format;
    97 
    98 	if ( volume == 0 ) {
    99 		return;
   100 	}
   101 	/* Mix the user-level audio format */
   102 	if ( current_audio ) {
   103 		if ( current_audio->convert.needed ) {
   104 			format = current_audio->convert.src_format;
   105 		} else {
   106 			format = current_audio->spec.format;
   107 		}
   108 	} else {
   109   		/* HACK HACK HACK */
   110 		format = AUDIO_S16;
   111 	}
   112 	switch (format) {
   113 
   114 		case AUDIO_U8: {
   115 #if defined(__M68000__) && defined(__GNUC__)
   116 			SDL_MixAudio_m68k_U8((char*)dst,(char*)src,(unsigned long)len,(long)volume,(char *)mix8);
   117 #else
   118 			Uint8 src_sample;
   119 
   120 			while ( len-- ) {
   121 				src_sample = *src;
   122 				ADJUST_VOLUME_U8(src_sample, volume);
   123 				*dst = mix8[*dst+src_sample];
   124 				++dst;
   125 				++src;
   126 			}
   127 #endif
   128 		}
   129 		break;
   130 
   131 		case AUDIO_S8: {
   132 #if defined(i386) && defined(__GNUC__) && defined(USE_ASMBLIT)
   133 			if (SDL_HasMMX())
   134 			{
   135 				SDL_MixAudio_MMX_S8((char*)dst,(char*)src,(unsigned int)len,(int)volume);
   136 			}
   137 			else
   138 #endif
   139 #if defined(USE_ASM_MIXER_VC)
   140 			if (SDL_HasMMX())
   141 			{
   142 				SDL_MixAudio_MMX_S8_VC((char*)dst,(char*)src,(unsigned int)len,(int)volume);
   143 			}
   144 			else
   145 #endif
   146 #if defined(__M68000__) && defined(__GNUC__)
   147 			SDL_MixAudio_m68k_S8((char*)dst,(char*)src,(unsigned long)len,(long)volume);
   148 #else
   149 			{
   150 			Sint8 *dst8, *src8;
   151 			Sint8 src_sample;
   152 			int dst_sample;
   153 			const int max_audioval = ((1<<(8-1))-1);
   154 			const int min_audioval = -(1<<(8-1));
   155 
   156 			src8 = (Sint8 *)src;
   157 			dst8 = (Sint8 *)dst;
   158 			while ( len-- ) {
   159 				src_sample = *src8;
   160 				ADJUST_VOLUME(src_sample, volume);
   161 				dst_sample = *dst8 + src_sample;
   162 				if ( dst_sample > max_audioval ) {
   163 					*dst8 = max_audioval;
   164 				} else
   165 				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 #if defined(i386) && defined(__GNUC__) && defined(USE_ASMBLIT)
   180 			if (SDL_HasMMX())
   181 			{
   182 				SDL_MixAudio_MMX_S16((char*)dst,(char*)src,(unsigned int)len,(int)volume);
   183 			}
   184 			else
   185 #elif defined(USE_ASM_MIXER_VC)
   186 			if (SDL_HasMMX())
   187 			{
   188 				SDL_MixAudio_MMX_S16_VC((char*)dst,(char*)src,(unsigned int)len,(int)volume);
   189 			}
   190 			else
   191 #endif
   192 #if defined(__M68000__) && defined(__GNUC__)
   193 			SDL_MixAudio_m68k_S16LSB((short*)dst,(short*)src,(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
   211 				if ( dst_sample < min_audioval ) {
   212 					dst_sample = min_audioval;
   213 				}
   214 				dst[0] = dst_sample&0xFF;
   215 				dst_sample >>= 8;
   216 				dst[1] = dst_sample&0xFF;
   217 				dst += 2;
   218 			}
   219 			}
   220 #endif
   221 		}
   222 		break;
   223 
   224 		case AUDIO_S16MSB: {
   225 #if defined(__M68000__) && defined(__GNUC__)
   226 			SDL_MixAudio_m68k_S16MSB((short*)dst,(short*)src,(unsigned long)len,(long)volume);
   227 #else
   228 			Sint16 src1, src2;
   229 			int dst_sample;
   230 			const int max_audioval = ((1<<(16-1))-1);
   231 			const int min_audioval = -(1<<(16-1));
   232 
   233 			len /= 2;
   234 			while ( len-- ) {
   235 				src1 = ((src[0])<<8|src[1]);
   236 				ADJUST_VOLUME(src1, volume);
   237 				src2 = ((dst[0])<<8|dst[1]);
   238 				src += 2;
   239 				dst_sample = src1+src2;
   240 				if ( dst_sample > max_audioval ) {
   241 					dst_sample = max_audioval;
   242 				} else
   243 				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