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Annotation of quake1/dmasim.c, revision 1.1.1.1

1.1       root        1: // =======================================================================
                      2: // Sound client does nothing but walk a circular sound buffer
                      3: // =======================================================================
                      4: 
                      5: //#include <fcntl.h>
                      6: #include <sys/types.h>
                      7: #include <sys/ipc.h>
                      8: #include <sys/shm.h>
                      9: #include <stdarg.h>
                     10: //#include <sys/ioctl.h>
                     11: #include <stdio.h>
                     12: #include <unistd.h>
                     13: 
                     14: #include "quakedef.h"
                     15: 
                     16: // =======================================================================
                     17: // Sound data & structures
                     18: // =======================================================================
                     19: 
                     20: int samplewidth;
                     21: int    numfragments;
                     22: int    fragmentsize;
                     23: int dma_buffer_size;
                     24: char *dma_buffer;
                     25: 
                     26: volatile dma_t *shm = 0;
                     27: 
                     28: void I_Error (char *error, ...)
                     29: { 
                     30:     va_list     argptr;
                     31:     char        string[1024];
                     32:    
                     33:        if ((int)shm>0)
                     34:        {
                     35:                shm->soundalive = 0;
                     36:                shmdt((void*)shm);
                     37:        }
                     38: 
                     39:     va_start (argptr,error);
                     40:     vsprintf (string,error,argptr);
                     41:     va_end (argptr);
                     42:        fprintf(stderr, "dmasim error: %s\n", string);
                     43:        exit(-1);
                     44: } 
                     45: 
                     46: void I_Warn (char *warning, ...)
                     47: { 
                     48:     va_list     argptr;
                     49:     char        string[1024];
                     50:     
                     51:     va_start (argptr,warning);
                     52:     vsprintf (string,warning,argptr);
                     53:     va_end (argptr);
                     54:        fprintf(stderr, "dmasim: %s\n", string);
                     55: } 
                     56: 
                     57: // =======================================================================
                     58: // log base-2
                     59: // =======================================================================
                     60: 
                     61: int Q_log2(int val)
                     62: {
                     63:        int answer;
                     64:        for (answer = 0 ; val>>=1 ; answer++);
                     65:        return answer;
                     66: }
                     67: 
                     68: void I_InitDMASound(void);
                     69: void I_ShutdownDMASound(void);
                     70: void I_SubmitDMABuffer(void *buffer, int size);
                     71: 
                     72: // =======================================================================
                     73: // Portable main control
                     74: // =======================================================================
                     75: 
                     76: void main(int c, char **v)
                     77: {
                     78: 
                     79:        int shmid;
                     80:        int     samplepos;
                     81:        int pagesize = getpagesize();
                     82:        int shmsize;
                     83:        int parent_pid;
                     84:        struct shmid_ds shmbuf;
                     85: 
                     86:        if (c < 2 || !atoi(v[1]))
                     87:                I_Error("Usage: dmasim <Size of DMA buffer in bytes>");
                     88: 
                     89:        parent_pid = getppid();
                     90: 
                     91:        // attach to the shared memory segment
                     92: 
                     93:        shmsize = atoi(v[1]);
                     94:        dma_buffer_size = 1<<Q_log2(shmsize);
                     95:        fprintf(stderr, "snd started\n");
                     96:        fprintf(stderr, "snd DMA buffer size = %d\n", dma_buffer_size);
                     97: 
                     98:        shmid = shmget(ftok(".", 0), shmsize, 0666);
                     99:        shm = (void *) shmat(shmid, 0, 0);
                    100:        if ((int)shm<=0)
                    101:                I_Error("Usage: Could not attach to shared memory");
                    102:        dma_buffer = (char *) (shm+1);
                    103: 
                    104: // initialize sound
                    105: 
                    106:        I_InitDMASound();
                    107: 
                    108:        samplewidth = shm->samplebits / 8;
                    109: 
                    110:        I_Warn("fragmentsize = %d\n", fragmentsize);
                    111: 
                    112: // play sound until told to stop
                    113: 
                    114:        shm->soundalive = 1;
                    115:        samplepos = 0;
                    116:        while (1)
                    117:        {
                    118:                I_SubmitDMABuffer(&dma_buffer[samplepos*samplewidth], fragmentsize);
                    119:                samplepos =     (samplepos + fragmentsize)
                    120:                                        & (shm->samples - 1);
                    121:                shm->samplepos = samplepos;
                    122:                shmctl(shmid, IPC_STAT, &shmbuf);
                    123:                if (!shm->gamealive || shmbuf.shm_nattch == 1)
                    124:                {
                    125:                        fprintf(stderr, "Quake appears to have left me.\n");
                    126:                        break;  // FIXME: not a cool solution
                    127:                }
                    128:        }
                    129: 
                    130:        // get rid of shared memory and close audio device
                    131: 
                    132:        shm->soundalive = 0;
                    133:        shmdt((void *) shm);
                    134: 
                    135:        I_ShutdownDMASound();
                    136: 
                    137:        exit(0);
                    138: 
                    139: }
                    140: 

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