/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2006 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken@libsdl.org
*/
#include "SDL_config.h"

/* This provides the default mixing callback for the SDL audio routines */

#include "SDL_cpuinfo.h"
#include "SDL_timer.h"
#include "SDL_audio.h"
#include "SDL_sysaudio.h"
#include "SDL_mixer_MMX.h"
#include "SDL_mixer_MMX_VC.h"
#include "SDL_mixer_m68k.h"

/* This table is used to add two sound values together and pin
 * the value to avoid overflow.  (used with permission from ARDI)
 * Changed to use 0xFE instead of 0xFF for better sound quality.
 */
static const Uint8 mix8[] = {
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x03,
    0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E,
    0x0F, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19,
    0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, 0x23, 0x24,
    0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F,
    0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A,
    0x3B, 0x3C, 0x3D, 0x3E, 0x3F, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45,
    0x46, 0x47, 0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F, 0x50,
    0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5A, 0x5B,
    0x5C, 0x5D, 0x5E, 0x5F, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66,
    0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70, 0x71,
    0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C,
    0x7D, 0x7E, 0x7F, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
    0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8F, 0x90, 0x91, 0x92,
    0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0x9B, 0x9C, 0x9D,
    0x9E, 0x9F, 0xA0, 0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8,
    0xA9, 0xAA, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF, 0xB0, 0xB1, 0xB2, 0xB3,
    0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE,
    0xBF, 0xC0, 0xC1, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7, 0xC8, 0xC9,
    0xCA, 0xCB, 0xCC, 0xCD, 0xCE, 0xCF, 0xD0, 0xD1, 0xD2, 0xD3, 0xD4,
    0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA, 0xDB, 0xDC, 0xDD, 0xDE, 0xDF,
    0xE0, 0xE1, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA,
    0xEB, 0xEC, 0xED, 0xEE, 0xEF, 0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5,
    0xF6, 0xF7, 0xF8, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE, 0xFE, 0xFE,
    0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE
};

/* The volume ranges from 0 - 128 */
#define ADJUST_VOLUME(s, v)	(s = (s*v)/SDL_MIX_MAXVOLUME)
#define ADJUST_VOLUME_U8(s, v)	(s = (((s-128)*v)/SDL_MIX_MAXVOLUME)+128)

void
SDL_MixAudio(Uint8 * dst, const Uint8 * src, Uint32 len, int volume)
{
    Uint16 format;

    if (volume == 0) {
        return;
    }
    /* Mix the user-level audio format */
    if (current_audio) {
        if (current_audio->convert.needed) {
            format = current_audio->convert.src_format;
        } else {
            format = current_audio->spec.format;
        }
    } else {
        /* HACK HACK HACK */
        format = AUDIO_S16;
    }
    switch (format) {

    case AUDIO_U8:
        {
#if defined(__GNUC__) && defined(__M68000__) && defined(SDL_ASSEMBLY_ROUTINES)
            SDL_MixAudio_m68k_U8((char *) dst, (char *) src,
                                 (unsigned long) len, (long) volume,
                                 (char *) mix8);
#else
            Uint8 src_sample;

            while (len--) {
                src_sample = *src;
                ADJUST_VOLUME_U8(src_sample, volume);
                *dst = mix8[*dst + src_sample];
                ++dst;
                ++src;
            }
#endif
        }
        break;

    case AUDIO_S8:
        {
#if defined(__GNUC__) && defined(__i386__) && defined(SDL_ASSEMBLY_ROUTINES)
            if (SDL_HasMMX()) {
                SDL_MixAudio_MMX_S8((char *) dst, (char *) src,
                                    (unsigned int) len, (int) volume);
            } else
#elif ((defined(_MSC_VER) && defined(_M_IX86)) || defined(__WATCOMC__)) && defined(SDL_ASSEMBLY_ROUTINES)
            if (SDL_HasMMX()) {
                SDL_MixAudio_MMX_S8_VC((char *) dst, (char *) src,
                                       (unsigned int) len, (int) volume);
            } else
#endif
#if defined(__GNUC__) && defined(__M68000__) && defined(SDL_ASSEMBLY_ROUTINES)
                SDL_MixAudio_m68k_S8((char *) dst, (char *) src,
                                     (unsigned long) len, (long) volume);
#else
            {
                Sint8 *dst8, *src8;
                Sint8 src_sample;
                int dst_sample;
                const int max_audioval = ((1 << (8 - 1)) - 1);
                const int min_audioval = -(1 << (8 - 1));

                src8 = (Sint8 *) src;
                dst8 = (Sint8 *) dst;
                while (len--) {
                    src_sample = *src8;
                    ADJUST_VOLUME(src_sample, volume);
                    dst_sample = *dst8 + src_sample;
                    if (dst_sample > max_audioval) {
                        *dst8 = max_audioval;
                    } else if (dst_sample < min_audioval) {
                        *dst8 = min_audioval;
                    } else {
                        *dst8 = dst_sample;
                    }
                    ++dst8;
                    ++src8;
                }
            }
#endif
        }
        break;

    case AUDIO_S16LSB:
        {
#if defined(__GNUC__) && defined(__i386__) && defined(SDL_ASSEMBLY_ROUTINES)
            if (SDL_HasMMX()) {
                SDL_MixAudio_MMX_S16((char *) dst, (char *) src,
                                     (unsigned int) len, (int) volume);
            } else
#elif ((defined(_MSC_VER) && defined(_M_IX86)) || defined(__WATCOMC__)) && defined(SDL_ASSEMBLY_ROUTINES)
            if (SDL_HasMMX()) {
                SDL_MixAudio_MMX_S16_VC((char *) dst, (char *) src,
                                        (unsigned int) len, (int) volume);
            } else
#endif
#if defined(__GNUC__) && defined(__M68000__) && defined(SDL_ASSEMBLY_ROUTINES)
                SDL_MixAudio_m68k_S16LSB((short *) dst, (short *) src,
                                         (unsigned long) len, (long) volume);
#else
            {
                Sint16 src1, src2;
                int dst_sample;
                const int max_audioval = ((1 << (16 - 1)) - 1);
                const int min_audioval = -(1 << (16 - 1));

                len /= 2;
                while (len--) {
                    src1 = ((src[1]) << 8 | src[0]);
                    ADJUST_VOLUME(src1, volume);
                    src2 = ((dst[1]) << 8 | dst[0]);
                    src += 2;
                    dst_sample = src1 + src2;
                    if (dst_sample > max_audioval) {
                        dst_sample = max_audioval;
                    } else if (dst_sample < min_audioval) {
                        dst_sample = min_audioval;
                    }
                    dst[0] = dst_sample & 0xFF;
                    dst_sample >>= 8;
                    dst[1] = dst_sample & 0xFF;
                    dst += 2;
                }
            }
#endif
        }
        break;

    case AUDIO_S16MSB:
        {
#if defined(__GNUC__) && defined(__M68000__) && defined(SDL_ASSEMBLY_ROUTINES)
            SDL_MixAudio_m68k_S16MSB((short *) dst, (short *) src,
                                     (unsigned long) len, (long) volume);
#else
            Sint16 src1, src2;
            int dst_sample;
            const int max_audioval = ((1 << (16 - 1)) - 1);
            const int min_audioval = -(1 << (16 - 1));

            len /= 2;
            while (len--) {
                src1 = ((src[0]) << 8 | src[1]);
                ADJUST_VOLUME(src1, volume);
                src2 = ((dst[0]) << 8 | dst[1]);
                src += 2;
                dst_sample = src1 + src2;
                if (dst_sample > max_audioval) {
                    dst_sample = max_audioval;
                } else if (dst_sample < min_audioval) {
                    dst_sample = min_audioval;
                }
                dst[1] = dst_sample & 0xFF;
                dst_sample >>= 8;
                dst[0] = dst_sample & 0xFF;
                dst += 2;
            }
#endif
        }
        break;

    default:                   /* If this happens... FIXME! */
        SDL_SetError("SDL_MixAudio(): unknown audio format");
        return;
    }
}

/* vi: set ts=4 sw=4 expandtab: */