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- /*
- * ---------------------------------------------------------------------------
- * sfxserver/mix.c
- *
- * Copyright by Terry Evans 1994
- * tevans@cs.utah.edu, tevans@slc.unisys.com
- * ---------------------------------------------------------------------------
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met: 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer. 2.
- * Redistributions in binary form must reproduce the above copyright notice,
- * this list of conditions and the following disclaimer in the documentation
- * and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND ANY
- * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
- * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- * ---------------------------------------------------------------------------
- */
-
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.h>
- #include <sys/types.h>
- #include <unistd.h>
-
-
- #include "global.h"
- #include "types.h"
- #include "channel.h"
- #include "io.h"
- #include "error.h"
-
-
- /* From channel.c */
- extern int channel_number;
-
-
- void M_Init(mix_t *mix, int frag_size)
- {
- IO_WriteStdout(" Setting up mix data structure\n");
-
- if((mix->clipped = (unsigned char *)calloc(sizeof(char), frag_size)) == NULL)
- E_FatalError("M_Init", "Unable to calloc clipped buffer");
-
- if((mix->silence = (unsigned char *)calloc(sizeof(char), frag_size)) == NULL)
- E_FatalError("M_Init", "Unable to calloc silence buffer");
-
- /* Set the silence to be silent */
- memset(mix->silence, 128, frag_size);
-
- mix->size = frag_size;
- }
-
-
- void M_DeInit(mix_t *mix)
- {
- if(mix->clipped != NULL)
- free(mix->clipped);
- }
-
-
- void M_MixChannels(mix_t *mix, channel_t **channel, int frag_size, int s_fd, int stereo)
- {
- int loop;
- int frag_offset;
- int num_channels_in_use;
- char data;
-
- /* This is so it isn't recalc'd at each iteration of the loop */
- int half_frag = frag_size >> 1;
-
- /* We are only doing a half a frag at a time */
- /* This is for stereo output */
- for(frag_offset = 0; frag_offset < half_frag; frag_offset++)
- {
- mix->unclipped_l = 0;
- mix->unclipped_r = 0;
- num_channels_in_use = 0;
-
- /* channel_number is the maximum channel number allocated so far */
- for(loop = 0; loop < channel_number; loop++)
- {
- /* See if it is a free channel */
- if(channel[loop] != NULL)
- {
- /* See if the channel is in use */
- if(channel[loop]->in_use)
- {
- /* Normalize the data */
- data = (*(channel[loop]->sample->data + channel[loop]->position)) ^ 0x80;
- mix->unclipped_l += channel[loop]->vol_left * (float)data;
- mix->unclipped_r += channel[loop]->vol_right * (float)data;
-
- num_channels_in_use++;
-
- /* Increment to the next byte of sound to read in */
- /* See if this sample is done being played */
- if(++channel[loop]->position >= channel[loop]->sample->length)
- channel[loop]->in_use = FALSE;
- }
- }
- }
-
- /* If there is nothing to play, just write out silence */
- if(num_channels_in_use == 0)
- {
- write(s_fd, mix->silence, frag_size);
- return;
- }
-
- /* Re-normalize the values */
- mix->unclipped_l += 128;
- mix->unclipped_r += 128;
-
- /* Left Channel */
- if(mix->unclipped_l < 0)
- mix->clipped[frag_offset << 1] = 0;
- else if(mix->unclipped_l > 255)
- mix->clipped[frag_offset << 1] = 255;
- else
- mix->clipped[frag_offset << 1] = mix->unclipped_l;
-
- /* Rigt Channel */
- if(mix->unclipped_r < 0)
- mix->clipped[(frag_offset << 1) + 1] = 0;
- else if(mix->unclipped_r > 255)
- mix->clipped[(frag_offset << 1) + 1] = 255;
- else
- mix->clipped[(frag_offset << 1) + 1] = mix->unclipped_r;
- }
-
- /* Write out the data */
- write(s_fd, mix->clipped, frag_size);
- }
-