effect_position.c

SDL_mixer 是一个基于 SDL 的混音器

			break;
		case 270:
        		*(ptr++) = (Sint16) SDL_SwapLE16(swaplr);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swapl);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swaprr);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swapr);
			break;
	}
    }
}

static void _Eff_position_s16lsb_c6(int chan, void *stream, int len, void *udata)
{
    /* 16 signed bits (lsb) * 6 channels. */
    volatile position_args *args = (volatile position_args *) udata;
    Sint16 *ptr = (Sint16 *) stream;
    int i;

    for (i = 0; i < len; i += sizeof (Sint16) * 6) {
        Sint16 swapl = (Sint16) ((((float) (Sint16) SDL_SwapLE16(*(ptr+0))) *
                                    args->left_f) * args->distance_f);
        Sint16 swapr = (Sint16) ((((float) (Sint16) SDL_SwapLE16(*(ptr+1))) *
                                    args->right_f) * args->distance_f);
        Sint16 swaplr = (Sint16) ((((float) (Sint16) SDL_SwapLE16(*(ptr+2))) *
                                    args->left_rear_f) * args->distance_f);
        Sint16 swaprr = (Sint16) ((((float) (Sint16) SDL_SwapLE16(*(ptr+3))) *
                                    args->right_rear_f) * args->distance_f);
        Sint16 swapce = (Sint16) ((((float) (Sint16) SDL_SwapLE16(*(ptr+4))) *
                                    args->center_f) * args->distance_f);
        Sint16 swapwf = (Sint16) ((((float) (Sint16) SDL_SwapLE16(*(ptr+5))) *
                                    args->lfe_f) * args->distance_f);
	switch (args->room_angle) {
		case 0:
        		*(ptr++) = (Sint16) SDL_SwapLE16(swapl);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swapr);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swaplr);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swaprr);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swapce);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swapwf);
			break;
		case 90:
        		*(ptr++) = (Sint16) SDL_SwapLE16(swapr);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swaprr);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swapl);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swaplr);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swapr)/2 + (Sint16) SDL_SwapLE16(swaprr)/2;
        		*(ptr++) = (Sint16) SDL_SwapLE16(swapwf);
			break;
		case 180:
        		*(ptr++) = (Sint16) SDL_SwapLE16(swaprr);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swaplr);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swapr);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swapl);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swaprr)/2 + (Sint16) SDL_SwapLE16(swaplr)/2;
        		*(ptr++) = (Sint16) SDL_SwapLE16(swapwf);
			break;
		case 270:
        		*(ptr++) = (Sint16) SDL_SwapLE16(swaplr);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swapl);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swaprr);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swapr);
        		*(ptr++) = (Sint16) SDL_SwapLE16(swapl)/2 + (Sint16) SDL_SwapLE16(swaplr)/2;
        		*(ptr++) = (Sint16) SDL_SwapLE16(swapwf);
			break;
	}
    }
}

static void _Eff_position_u16msb(int chan, void *stream, int len, void *udata)
{
    /* 16 signed bits (lsb) * 2 channels. */
    volatile position_args *args = (volatile position_args *) udata;
    Uint16 *ptr = (Uint16 *) stream;
    int i;

    for (i = 0; i < len; i += sizeof (Sint16) * 2) {
        Sint16 sampl = (Sint16) (SDL_SwapBE16(*(ptr+0)) - 32768);
        Sint16 sampr = (Sint16) (SDL_SwapBE16(*(ptr+1)) - 32768);
        
        Uint16 swapl = (Uint16) ((Sint16) (((float) sampl * args->left_f)
                                    * args->distance_f) + 32768);
        Uint16 swapr = (Uint16) ((Sint16) (((float) sampr * args->right_f)
                                    * args->distance_f) + 32768);

	if (args->room_angle == 180) {
        	*(ptr++) = (Uint16) SDL_SwapBE16(swapr);
        	*(ptr++) = (Uint16) SDL_SwapBE16(swapl);
	}
	else {
        	*(ptr++) = (Uint16) SDL_SwapBE16(swapl);
        	*(ptr++) = (Uint16) SDL_SwapBE16(swapr);
	}
    }
}
static void _Eff_position_u16msb_c4(int chan, void *stream, int len, void *udata)
{
    /* 16 signed bits (lsb) * 4 channels. */
    volatile position_args *args = (volatile position_args *) udata;
    Uint16 *ptr = (Uint16 *) stream;
    int i;

    for (i = 0; i < len; i += sizeof (Sint16) * 4) {
        Sint16 sampl = (Sint16) (SDL_SwapBE16(*(ptr+0)) - 32768);
        Sint16 sampr = (Sint16) (SDL_SwapBE16(*(ptr+1)) - 32768);
        Sint16 samplr = (Sint16) (SDL_SwapBE16(*(ptr+2)) - 32768);
        Sint16 samprr = (Sint16) (SDL_SwapBE16(*(ptr+3)) - 32768);
        
        Uint16 swapl = (Uint16) ((Sint16) (((float) sampl * args->left_f)
                                    * args->distance_f) + 32768);
        Uint16 swapr = (Uint16) ((Sint16) (((float) sampr * args->right_f)
                                    * args->distance_f) + 32768);
        Uint16 swaplr = (Uint16) ((Sint16) (((float) samplr * args->left_rear_f)
                                    * args->distance_f) + 32768);
        Uint16 swaprr = (Uint16) ((Sint16) (((float) samprr * args->right_rear_f)
                                    * args->distance_f) + 32768);

	switch (args->room_angle) {
		case 0:
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapl);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swaplr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swaprr);
			break;
		case 90:
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swaprr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapl);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swaplr);
			break;
		case 180:
        		*(ptr++) = (Uint16) SDL_SwapBE16(swaprr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swaplr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapl);
			break;
		case 270:
        		*(ptr++) = (Uint16) SDL_SwapBE16(swaplr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapl);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swaprr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapr);
			break;
	}
    }
}
static void _Eff_position_u16msb_c6(int chan, void *stream, int len, void *udata)
{
    /* 16 signed bits (lsb) * 6 channels. */
    volatile position_args *args = (volatile position_args *) udata;
    Uint16 *ptr = (Uint16 *) stream;
    int i;

    for (i = 0; i < len; i += sizeof (Sint16) * 6) {
        Sint16 sampl = (Sint16) (SDL_SwapBE16(*(ptr+0)) - 32768);
        Sint16 sampr = (Sint16) (SDL_SwapBE16(*(ptr+1)) - 32768);
        Sint16 samplr = (Sint16) (SDL_SwapBE16(*(ptr+2)) - 32768);
        Sint16 samprr = (Sint16) (SDL_SwapBE16(*(ptr+3)) - 32768);
        Sint16 sampce = (Sint16) (SDL_SwapBE16(*(ptr+4)) - 32768);
        Sint16 sampwf = (Sint16) (SDL_SwapBE16(*(ptr+5)) - 32768);
        
        Uint16 swapl = (Uint16) ((Sint16) (((float) sampl * args->left_f)
                                    * args->distance_f) + 32768);
        Uint16 swapr = (Uint16) ((Sint16) (((float) sampr * args->right_f)
                                    * args->distance_f) + 32768);
        Uint16 swaplr = (Uint16) ((Sint16) (((float) samplr * args->left_rear_f)
                                    * args->distance_f) + 32768);
        Uint16 swaprr = (Uint16) ((Sint16) (((float) samprr * args->right_rear_f)
                                    * args->distance_f) + 32768);
        Uint16 swapce = (Uint16) ((Sint16) (((float) sampce * args->center_f)
                                    * args->distance_f) + 32768);
        Uint16 swapwf = (Uint16) ((Sint16) (((float) sampwf * args->lfe_f)
                                    * args->distance_f) + 32768);

	switch (args->room_angle) {
		case 0:
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapl);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swaplr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swaprr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapce);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapwf);
			break;
		case 90:
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swaprr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapl);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swaplr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapr)/2 + (Uint16) SDL_SwapBE16(swaprr)/2;
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapwf);
			break;
		case 180:
        		*(ptr++) = (Uint16) SDL_SwapBE16(swaprr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swaplr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapl);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swaprr)/2 + (Uint16) SDL_SwapBE16(swaplr)/2;
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapwf);
			break;
		case 270:
        		*(ptr++) = (Uint16) SDL_SwapBE16(swaplr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapl);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swaprr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapr);
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapl)/2 + (Uint16) SDL_SwapBE16(swaplr)/2;
        		*(ptr++) = (Uint16) SDL_SwapBE16(swapwf);
			break;
	}
    }
}

static void _Eff_position_s16msb(int chan, void *stream, int len, void *udata)
{
    /* 16 signed bits (lsb) * 2 channels. */
    volatile position_args *args = (volatile position_args *) udata;
    Sint16 *ptr = (Sint16 *) stream;
    int i;

    for (i = 0; i < len; i += sizeof (Sint16) * 2) {
        Sint16 swapl = (Sint16) ((((float) (Sint16) SDL_SwapBE16(*(ptr+0))) *
                                    args->left_f) * args->distance_f);
        Sint16 swapr = (Sint16) ((((float) (Sint16) SDL_SwapBE16(*(ptr+1))) *
                                    args->right_f) * args->distance_f);
        *(ptr++) = (Sint16) SDL_SwapBE16(swapl);
        *(ptr++) = (Sint16) SDL_SwapBE16(swapr);
    }
}
static void _Eff_position_s16msb_c4(int chan, void *stream, int len, void *udata)
{
    /* 16 signed bits (lsb) * 4 channels. */
    volatile position_args *args = (volatile position_args *) udata;
    Sint16 *ptr = (Sint16 *) stream;
    int i;

    for (i = 0; i < len; i += sizeof (Sint16) * 4) {
        Sint16 swapl = (Sint16) ((((float) (Sint16) SDL_SwapBE16(*(ptr+0))) *
                                    args->left_f) * args->distance_f);
        Sint16 swapr = (Sint16) ((((float) (Sint16) SDL_SwapBE16(*(ptr+1))) *
                                    args->right_f) * args->distance_f);
        Sint16 swaplr = (Sint16) ((((float) (Sint16) SDL_SwapBE16(*(ptr+2))) *
                                    args->left_rear_f) * args->distance_f);
        Sint16 swaprr = (Sint16) ((((float) (Sint16) SDL_SwapBE16(*(ptr+3))) *
                                    args->right_rear_f) * args->distance_f);
	switch (args->room_angle) {
		case 0:
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapl);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swaplr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swaprr);
			break;
		case 90:
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swaprr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapl);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swaplr);
			break;
		case 180:
        		*(ptr++) = (Sint16) SDL_SwapBE16(swaprr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swaplr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapl);
			break;
		case 270:
        		*(ptr++) = (Sint16) SDL_SwapBE16(swaplr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapl);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swaprr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapr);
			break;
	}
    }
}
static void _Eff_position_s16msb_c6(int chan, void *stream, int len, void *udata)
{
    /* 16 signed bits (lsb) * 6 channels. */
    volatile position_args *args = (volatile position_args *) udata;
    Sint16 *ptr = (Sint16 *) stream;
    int i;

    for (i = 0; i < len; i += sizeof (Sint16) * 6) {
        Sint16 swapl = (Sint16) ((((float) (Sint16) SDL_SwapBE16(*(ptr+0))) *
                                    args->left_f) * args->distance_f);
        Sint16 swapr = (Sint16) ((((float) (Sint16) SDL_SwapBE16(*(ptr+1))) *
                                    args->right_f) * args->distance_f);
        Sint16 swaplr = (Sint16) ((((float) (Sint16) SDL_SwapBE16(*(ptr+2))) *
                                    args->left_rear_f) * args->distance_f);
        Sint16 swaprr = (Sint16) ((((float) (Sint16) SDL_SwapBE16(*(ptr+3))) *
                                    args->right_rear_f) * args->distance_f);
        Sint16 swapce = (Sint16) ((((float) (Sint16) SDL_SwapBE16(*(ptr+4))) *
                                    args->center_f) * args->distance_f);
        Sint16 swapwf = (Sint16) ((((float) (Sint16) SDL_SwapBE16(*(ptr+5))) *
                                    args->lfe_f) * args->distance_f);

	switch (args->room_angle) {
		case 0:
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapl);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swaplr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swaprr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapce);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapwf);
			break;
		case 90:
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swaprr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapl);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swaplr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapr)/2 + (Sint16) SDL_SwapBE16(swaprr)/2;
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapwf);
			break;
		case 180:
        		*(ptr++) = (Sint16) SDL_SwapBE16(swaprr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swaplr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapl);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swaprr)/2 + (Sint16) SDL_SwapBE16(swaplr)/2;
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapwf);
			break;
		case 270:
        		*(ptr++) = (Sint16) SDL_SwapBE16(swaplr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapl);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swaprr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapr);
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapl)/2 + (Sint16) SDL_SwapBE16(swaplr)/2;
        		*(ptr++) = (Sint16) SDL_SwapBE16(swapwf);
			break;
	}
    }
}

static void init_position_args(position_args *args)
{
    memset(args, '\0', sizeof (position_args));
    args->in_use = 0;
    args->room_angle = 0;
    args->left_u8 = args->right_u8 = args->distance_u8 = 255;
    args->left_f  = args->right_f  = args->distance_f  = 1.0f;
    args->left_rear_u8 = args->right_rear_u8 = args->center_u8 = args->lfe_u8 = 255;
    args->left_rear_f = args->right_rear_f = args->center_f = args->lfe_f = 1.0f;
    Mix_QuerySpec(NULL, NULL, (int *) &args->channels);
}


static position_args *get_position_arg(int channel)
{
    void *rc;
    int i;

    if (channel < 0) {
        if (pos_args_global == NULL) {
            pos_args_global = malloc(sizeof (position_args));
            if (pos_args_global == NULL) {
                Mix_SetError("Out of memory");
                return(NULL);
            }
            init_position_args(pos_args_global);
        }

        return(pos_args_global);
    }

    if (channel >= position_channels) {
        rc = realloc(pos_args_array, (channel + 1) * sizeof (position_args *));
        if (rc == NULL) {
            Mix_SetError("Out of memory");
            return(NULL);
        }
        pos_args_array = (position_args **) rc;
        for (i = position_channels; i <= channel; i++) {
            pos_args_array[i] = NULL;
        }
        position_channels = channel + 1;
    }

    if (pos_args_array[channel] == NULL) {
        pos_args_array[channel] = (position_args *)malloc(sizeof(position_args));
        if (pos_args_array[channel] == NULL) {
            Mix_SetError("Out of memory");
            return(NULL);
        }
        init_position_args(pos_args_array[channel]);
    }

    return(pos_args_array[channel]);
}


static Mix_EffectFunc_t get_position_effect_func(Uint16 format, int channels)
{
    Mix_EffectFunc_t f = NULL;

    switch (format) {
        case AUDIO_U8:
	    switch (channels) {
		    case 1: