A-Law to Signed linear conversion. More...
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Defines | |
| #define | AST_ALAW(a) (__ast_alaw[(int)(a)]) |
| #define | AST_ALAW_AMI_MASK 0x55 |
| #define | AST_ALAW_BIT_LOSS 4 |
| #define | AST_ALAW_SIGN_BIT 0x80 |
| #define | AST_ALAW_STEP (1 << AST_ALAW_BIT_LOSS) |
| #define | AST_ALAW_TAB_SIZE (32768 / AST_ALAW_STEP + 1) |
| #define | AST_LIN2A(a) (__ast_lin2a[((unsigned short)(a)) >> 3]) |
Functions | |
| void | ast_alaw_init (void) |
| To init the alaw to slinear conversion stuff, this needs to be run. | |
Variables | |
| short | __ast_alaw [256] |
| unsigned char | __ast_lin2a [8192] |
| converts signed linear to alaw | |
Detailed Description
A-Law to Signed linear conversion.
Definition in file alaw.h.
Define Documentation
| #define AST_ALAW | ( | a | ) | (__ast_alaw[(int)(a)]) |
Definition at line 84 of file alaw.h.
Referenced by alawtolin_framein(), ast_alaw_init(), ast_dsp_process(), calc_energy(), dahdi_r2_alaw_to_linear(), fill_rxgain(), fill_txgain(), and load_module().
| #define AST_ALAW_STEP (1 << AST_ALAW_BIT_LOSS) |
Definition at line 33 of file alaw.h.
Referenced by ast_alaw_init().
| #define AST_LIN2A | ( | a | ) | (__ast_lin2a[((unsigned short)(a)) >> 3]) |
Definition at line 50 of file alaw.h.
Referenced by ast_alaw_init(), ast_dsp_process(), dahdi_r2_linear_to_alaw(), fill_rxgain(), fill_txgain(), lintoalaw_framein(), and load_module().
Function Documentation
| void ast_alaw_init | ( | void | ) |
To init the alaw to slinear conversion stuff, this needs to be run.
Definition at line 150 of file alaw.c.
References alaw2linear(), AST_ALAW, AST_ALAW_STEP, AST_LIN2A, ast_log(), linear2alaw(), LOG_NOTICE, and LOG_WARNING.
Referenced by main().
{
int i;
/*
* Set up mu-law conversion table
*/
#ifndef G711_NEW_ALGORITHM
for (i = 0; i < 256; i++) {
__ast_alaw[i] = alaw2linear(i);
}
/* set up the reverse (mu-law) conversion table */
for (i = -32768; i < 32768; i++) {
__ast_lin2a[((unsigned short)i) >> 3] = linear2alaw(i);
}
#else
for (i = 0; i < 256; i++) {
__ast_alaw[i] = alaw2linear(i);
}
/* set up the reverse (a-law) conversion table */
for (i = 0; i <= 32768; i += AST_ALAW_STEP) {
AST_LIN2A_LOOKUP(i) = linear2alaw(i, 0 /* half-cooked */);
}
#endif
#ifdef TEST_CODING_TABLES
for (i = -32768; i < 32768; ++i) {
#ifndef G711_NEW_ALGORITHM
unsigned char e1 = linear2alaw(i);
#else
unsigned char e1 = linear2alaw(i, 1);
#endif
short d1 = alaw2linear(e1);
unsigned char e2 = AST_LIN2A(i);
short d2 = alaw2linear(e2);
short d3 = AST_ALAW(e1);
if (e1 != e2 || d1 != d3 || d2 != d3) {
ast_log(LOG_WARNING, "a-Law coding tables test failed on %d: e1=%u, e2=%u, d1=%d, d2=%d\n",
i, (unsigned)e1, (unsigned)e2, (int)d1, (int)d2);
}
}
ast_log(LOG_NOTICE, "a-Law coding tables test complete.\n");
#endif /* TEST_CODING_TABLES */
#ifdef TEST_TANDEM_TRANSCODING
/* tandem transcoding test */
for (i = -32768; i < 32768; ++i) {
unsigned char e1 = AST_LIN2A(i);
short d1 = AST_ALAW(e1);
unsigned char e2 = AST_LIN2A(d1);
short d2 = AST_ALAW(e2);
unsigned char e3 = AST_LIN2A(d2);
short d3 = AST_ALAW(e3);
if (e1 != e2 || e2 != e3 || d1 != d2 || d2 != d3) {
ast_log(LOG_WARNING, "a-Law tandem transcoding test failed on %d: e1=%u, e2=%u, d1=%d, d2=%d, d3=%d\n",
i, (unsigned)e1, (unsigned)e2, (int)d1, (int)d2, (int)d3);
}
}
ast_log(LOG_NOTICE, "a-Law tandem transcoding test complete.\n");
#endif /* TEST_TANDEM_TRANSCODING */
}
Variable Documentation
| short __ast_alaw[256] |
| unsigned char __ast_lin2a[8192] |
