effect_position.c

SDL_mixer 是一个基于 SDL 的混音器

/*
    SDL_mixer:  An audio mixer library based on the SDL library
    Copyright (C) 1997-2004 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 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
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    This file by Ryan C. Gordon ([e-mail])

    These are some internally supported special effects that use SDL_mixer's
    effect callback API. They are meant for speed over quality.  :)
*/

/* $Id: effect_position.c 1451 2004-11-15 23:36:49Z slouken $ */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "SDL.h"
#include "SDL_mixer.h"
#include "SDL_endian.h"

#define __MIX_INTERNAL_EFFECT__
#include "effects_internal.h"

/* profile code:
    #include <sys/time.h>
    #include <unistd.h>
    struct timeval tv1;
    struct timeval tv2;
    
    gettimeofday(&tv1, NULL);

        ... do your thing here ...

    gettimeofday(&tv2, NULL);
    printf("%ld\n", tv2.tv_usec - tv1.tv_usec);
*/


/*
 * Positional effects...panning, distance attenuation, etc.
 */

typedef struct _Eff_positionargs
{
    volatile float left_f;
    volatile float right_f;
    volatile Uint8 left_u8;
    volatile Uint8 right_u8;
    volatile float left_rear_f;
    volatile float right_rear_f;
    volatile float center_f;
    volatile float lfe_f;
    volatile Uint8 left_rear_u8;
    volatile Uint8 right_rear_u8;
    volatile Uint8 center_u8;
    volatile Uint8 lfe_u8;
    volatile float distance_f;
    volatile Uint8 distance_u8;
    volatile Sint16 room_angle;
    volatile int in_use;
    volatile int channels;
} position_args;

static position_args **pos_args_array = NULL;
static position_args *pos_args_global = NULL;
static int position_channels = 0;

/* This just frees up the callback-specific data. */
static void _Eff_PositionDone(int channel, void *udata)
{
    if (channel < 0) {
        if (pos_args_global != NULL) {
            free(pos_args_global);
            pos_args_global = NULL;
        }
    }

    else if (pos_args_array[channel] != NULL) {
        free(pos_args_array[channel]);
        pos_args_array[channel] = NULL;
    }
}


static void _Eff_position_u8(int chan, void *stream, int len, void *udata)
{
    volatile position_args *args = (volatile position_args *) udata;
    Uint8 *ptr = (Uint8 *) stream;
    int i;

        /*
         * if there's only a mono channnel (the only way we wouldn't have
         *  a len divisible by 2 here), then left_f and right_f are always
         *  1.0, and are therefore throwaways.
         */
    if (len % sizeof (Uint16) != 0) {
        *ptr = (Uint8) (((float) *ptr) * args->distance_f);
        ptr++;
        len--;
    }

    if (args->room_angle == 0)
    for (i = 0; i < len; i += sizeof (Uint8) * 2) {
        /* must adjust the sample so that 0 is the center */
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_f) * args->distance_f) + 128);
        ptr++;
    }
    else for (i = 0; i < len; i += sizeof (Uint8) * 2) {
        /* must adjust the sample so that 0 is the center */
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_f) * args->distance_f) + 128);
        ptr++;
    }
}
static void _Eff_position_u8_c4(int chan, void *stream, int len, void *udata)
{
    volatile position_args *args = (volatile position_args *) udata;
    Uint8 *ptr = (Uint8 *) stream;
    int i;

        /*
         * if there's only a mono channnel (the only way we wouldn't have
         *  a len divisible by 2 here), then left_f and right_f are always
         *  1.0, and are therefore throwaways.
         */
    if (len % sizeof (Uint16) != 0) {
        *ptr = (Uint8) (((float) *ptr) * args->distance_f);
        ptr++;
        len--;
    }

    if (args->room_angle == 0)
    for (i = 0; i < len; i += sizeof (Uint8) * 6) {
        /* must adjust the sample so that 0 is the center */
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_rear_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_rear_f) * args->distance_f) + 128);
        ptr++;
    }
    else if (args->room_angle == 90)
    for (i = 0; i < len; i += sizeof (Uint8) * 6) {
        /* must adjust the sample so that 0 is the center */
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_rear_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_rear_f) * args->distance_f) + 128);
        ptr++;
    }
    else if (args->room_angle == 180)
    for (i = 0; i < len; i += sizeof (Uint8) * 6) {
        /* must adjust the sample so that 0 is the center */
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_rear_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_rear_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_f) * args->distance_f) + 128);
        ptr++;
    }
    else if (args->room_angle == 270)
    for (i = 0; i < len; i += sizeof (Uint8) * 6) {
        /* must adjust the sample so that 0 is the center */
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_rear_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_rear_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_f) * args->distance_f) + 128);
        ptr++;
    }
}


static void _Eff_position_u8_c6(int chan, void *stream, int len, void *udata)
{
    volatile position_args *args = (volatile position_args *) udata;
    Uint8 *ptr = (Uint8 *) stream;
    int i;

        /*
         * if there's only a mono channnel (the only way we wouldn't have
         *  a len divisible by 2 here), then left_f and right_f are always
         *  1.0, and are therefore throwaways.
         */
    if (len % sizeof (Uint16) != 0) {
        *ptr = (Uint8) (((float) *ptr) * args->distance_f);
        ptr++;
        len--;
    }

    if (args->room_angle == 0)
    for (i = 0; i < len; i += sizeof (Uint8) * 6) {
        /* must adjust the sample so that 0 is the center */
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_rear_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_rear_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->center_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->lfe_f) * args->distance_f) + 128);
        ptr++;
    }
    else if (args->room_angle == 90)
    for (i = 0; i < len; i += sizeof (Uint8) * 6) {
        /* must adjust the sample so that 0 is the center */
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_rear_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_rear_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_rear_f) * args->distance_f/2) + 128)
            + (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_f) * args->distance_f/2) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->lfe_f) * args->distance_f) + 128);
        ptr++;
    }
    else if (args->room_angle == 180)
    for (i = 0; i < len; i += sizeof (Uint8) * 6) {
        /* must adjust the sample so that 0 is the center */
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_rear_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_rear_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_rear_f) * args->distance_f/2) + 128)
            + (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_rear_f) * args->distance_f/2) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->lfe_f) * args->distance_f) + 128);
        ptr++;
    }
    else if (args->room_angle == 270)
    for (i = 0; i < len; i += sizeof (Uint8) * 6) {
        /* must adjust the sample so that 0 is the center */
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_rear_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_rear_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->right_f) * args->distance_f) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_f) * args->distance_f/2) + 128)
            + (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->left_rear_f) * args->distance_f/2) + 128);
        ptr++;
        *ptr = (Uint8) ((Sint8) ((((float) (Sint8) (*ptr - 128)) 
            * args->lfe_f) * args->distance_f) + 128);
        ptr++;
    }
}


/*
 * This one runs about 10.1 times faster than the non-table version, with
 *  no loss in quality. It does, however, require 64k of memory for the
 *  lookup table. Also, this will only update position information once per
 *  call; the non-table version always checks the arguments for each sample,
 *  in case the user has called Mix_SetPanning() or whatnot again while this
 *  callback is running.
 */
static void _Eff_position_table_u8(int chan, void *stream, int len, void *udata)
{
    volatile position_args *args = (volatile position_args *) udata;
    Uint8 *ptr = (Uint8 *) stream;
    Uint32 *p;
    int i;
    Uint8 *l = ((Uint8 *) _Eff_volume_table) + (256 * args->left_u8);
    Uint8 *r = ((Uint8 *) _Eff_volume_table) + (256 * args->right_u8);
    Uint8 *d = ((Uint8 *) _Eff_volume_table) + (256 * args->distance_u8);

    if (args->room_angle == 180) {
	    Uint8 *temp = l;
	    l = r;
	    r = temp;
    }
        /*
         * if there's only a mono channnel, then l[] and r[] are always
         *  volume 255, and are therefore throwaways. Still, we have to
         *  be sure not to overrun the audio buffer...
         */
    while (len % sizeof (Uint32) != 0) {
        *ptr = d[l[*ptr]];
        ptr++;
        if (args->channels > 1) {
            *ptr = d[r[*ptr]];
            ptr++;
        }
        len -= args->channels;
    }

    p = (Uint32 *) ptr;

    for (i = 0; i < len; i += sizeof (Uint32)) {
#if (SDL_BYTEORDER == SDL_BIG_ENDIAN)
        *(p++) = (d[l[(*p & 0xFF000000) >> 24]] << 24) |
                 (d[r[(*p & 0x00FF0000) >> 16]] << 16) |
                 (d[l[(*p & 0x0000FF00) >>  8]] <<  8) |
                 (d[r[(*p & 0x000000FF)      ]]      ) ;
#else
        *(p++) = (d[r[(*p & 0xFF000000) >> 24]] << 24) |
                 (d[l[(*p & 0x00FF0000) >> 16]] << 16) |
                 (d[r[(*p & 0x0000FF00) >>  8]] <<  8) |
                 (d[l[(*p & 0x000000FF)      ]]      ) ;
#endif
    }
}


static void _Eff_position_s8(int chan, void *stream, int len, void *udata)
{
    volatile position_args *args = (volatile position_args *) udata;