#include "asterisk.h"
#include "asterisk/alaw.h"
Include dependency graph for alaw.c:
Go to the source code of this file.
Defines | |
#define | AMI_MASK 0x55 |
Functions | |
static short int | alaw2linear (unsigned char alaw) |
void | ast_alaw_init (void) |
static unsigned char | linear2alaw (short int linear) |
Variables | |
short | __ast_alaw [256] |
unsigned char | __ast_lin2a [8192] |
Definition in file alaw.c.
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Definition at line 31 of file alaw.c. Referenced by alaw2linear(), and linear2alaw(). |
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Definition at line 67 of file alaw.c. References AMI_MASK. Referenced by ast_alaw_init(). 00068 { 00069 int i; 00070 int seg; 00071 00072 alaw ^= AMI_MASK; 00073 i = ((alaw & 0x0F) << 4); 00074 seg = (((int) alaw & 0x70) >> 4); 00075 if (seg) 00076 i = (i + 0x100) << (seg - 1); 00077 return (short int) ((alaw & 0x80) ? i : -i); 00078 }
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To init the ulaw to slinear conversion stuff, this needs to be run. Definition at line 83 of file alaw.c. References __ast_alaw, __ast_lin2a, alaw2linear(), and linear2alaw(). Referenced by main(). 00084 { 00085 int i; 00086 /* 00087 * Set up mu-law conversion table 00088 */ 00089 for(i = 0;i < 256;i++) 00090 { 00091 __ast_alaw[i] = alaw2linear(i); 00092 } 00093 /* set up the reverse (mu-law) conversion table */ 00094 for(i = -32768; i < 32768; i++) 00095 { 00096 __ast_lin2a[((unsigned short)i) >> 3] = linear2alaw(i); 00097 } 00098 00099 }
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Definition at line 33 of file alaw.c. References AMI_MASK. Referenced by ast_alaw_init(). 00034 { 00035 int mask; 00036 int seg; 00037 int pcm_val; 00038 static int seg_end[8] = 00039 { 00040 0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF 00041 }; 00042 00043 pcm_val = linear; 00044 if (pcm_val >= 0) 00045 { 00046 /* Sign (7th) bit = 1 */ 00047 mask = AMI_MASK | 0x80; 00048 } 00049 else 00050 { 00051 /* Sign bit = 0 */ 00052 mask = AMI_MASK; 00053 pcm_val = -pcm_val; 00054 } 00055 00056 /* Convert the scaled magnitude to segment number. */ 00057 for (seg = 0; seg < 8; seg++) 00058 { 00059 if (pcm_val <= seg_end[seg]) 00060 break; 00061 } 00062 /* Combine the sign, segment, and quantization bits. */ 00063 return ((seg << 4) | ((pcm_val >> ((seg) ? (seg + 3) : 4)) & 0x0F)) ^ mask; 00064 }
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help Definition at line 81 of file alaw.c. Referenced by ast_alaw_init(). |
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Definition at line 80 of file alaw.c. Referenced by ast_alaw_init(). |