Asterisk - The Open Source Telephony Project GIT-master-1f1c5bb
Macros | Functions
lpc.c File Reference
#include <stdio.h>
#include <assert.h>
#include "private.h"
#include "gsm.h"
#include "proto.h"
Include dependency graph for lpc.c:

Go to the source code of this file.

Macros

#define NEXTI   sl = *++sp
 
#define SCALE(n)
 
#define STEP(A, B, MAC, MIC)
 
#define STEP(k)   L_ACF[k] += ((longword)sl * sp[ -(k) ]);
 

Functions

static void Quantization_and_coding P1 ((LAR), register word *LAR)
 
static void Transformation_to_Log_Area_Ratios P1 ((r), register word *r)
 
static void Reflection_coefficients P2 ((L_ACF, r), longword *L_ACF, register word *r)
 
static void Autocorrelation P2 ((s, L_ACF), word *s, longword *L_ACF)
 
void Gsm_LPC_Analysis P3 ((S, s, LARc), struct gsm_state *S, word *s, word *LARc)
 

Macro Definition Documentation

◆ NEXTI

#define NEXTI   sl = *++sp

◆ SCALE

#define SCALE (   n)
Value:
case n: for (k = 0; k <= 159; k++) \
s[k] = (word)GSM_MULT_R( s[k], 16384 >> (n-1) );\
break;
word
short word
Definition: codecs/gsm/inc/private.h:12
GSM_MULT_R
#define GSM_MULT_R(a, b)
Definition: codecs/gsm/inc/private.h:92

◆ STEP [1/2]

#define STEP (   A,
  B,
  MAC,
  MIC 
)

◆ STEP [2/2]

#define STEP (   k)    L_ACF[k] += ((longword)sl * sp[ -(k) ]);

Function Documentation

◆ P1() [1/2]

static void Quantization_and_coding P1 ( (LAR)  ,
register word *  LAR 
)
static

Definition at line 319 of file lpc.c.

322{
323 register word temp;
324
325
326 /* This procedure needs four tables; the following equations
327 * give the optimum scaling for the constants:
328 *
329 * A[0..7] = integer( real_A[0..7] * 1024 )
330 * B[0..7] = integer( real_B[0..7] * 512 )
331 * MAC[0..7] = maximum of the LARc[0..7]
332 * MIC[0..7] = minimum of the LARc[0..7]
333 */
334
335# undef STEP
336# define STEP( A, B, MAC, MIC ) \
337 temp = (word)GSM_MULT( A, *LAR ); \
338 temp = GSM_ADD( temp, B ); \
339 temp = GSM_ADD( temp, 256 ); \
340 temp = (word)SASR( temp, 9 ); \
341 *LAR = temp>MAC ? MAC - MIC : (temp<MIC ? 0 : temp - MIC); \
342 LAR++;
343
344 STEP( 20480, 0, 31, -32 );
345 STEP( 20480, 0, 31, -32 );
346 STEP( 20480, 2048, 15, -16 );
347 STEP( 20480, -2560, 15, -16 );
348
349 STEP( 13964, 94, 7, -8 );
350 STEP( 15360, -1792, 7, -8 );
351 STEP( 8534, -341, 3, -4 );
352 STEP( 9036, -1144, 3, -4 );
353
354# undef STEP
355}
STEP
#define STEP(k)

References STEP.

◆ P1() [2/2]

static void Transformation_to_Log_Area_Ratios P1 ( (r)  ,
register word *  r 
)
static

Definition at line 278 of file lpc.c.

288{
289 register word temp;
290 register int i;
291
292
293 /* Computation of the LAR[0..7] from the r[0..7]
294 */
295 for (i = 1; i <= 8; i++, r++) {
296
297 temp = *r;
298 temp = GSM_ABS(temp);
299 assert(temp >= 0);
300
301 if (temp < 22118) {
302 temp >>= 1;
303 } else if (temp < 31130) {
304 assert( temp >= 11059 );
305 temp -= 11059;
306 } else {
307 assert( temp >= 26112 );
308 temp -= 26112;
309 temp <<= 2;
310 }
311
312 *r = *r < 0 ? -temp : temp;
313 assert( *r != MIN_WORD );
314 }
315}
MIN_WORD
#define MIN_WORD
Definition: codecs/gsm/inc/private.h:44
GSM_ABS
#define GSM_ABS(a)
Definition: codecs/gsm/inc/private.h:168

References GSM_ABS, and MIN_WORD.

◆ P2() [1/2]

static void Reflection_coefficients P2 ( (L_ACF, r)  ,
longword *  L_ACF,
register word *  r 
)
static

Definition at line 210 of file lpc.c.

214{
215 register int i, m, n;
216 register word temp;
217 word ACF[9]; /* 0..8 */
218 word P[ 9]; /* 0..8 */
219 word K[ 9]; /* 2..8 */
220
221 /* Schur recursion with 16 bits arithmetic.
222 */
223
224 if (L_ACF[0] == 0) {
225 for (i = 8; i--; *r++ = 0) ;
226 return;
227 }
228
229 assert( L_ACF[0] != 0 );
230 temp = gsm_norm( L_ACF[0] );
231
232 assert(temp >= 0 && temp < 32);
233
234 /* ? overflow ? */
235 for (i = 0; i <= 8; i++) ACF[i] = (word)SASR( L_ACF[i] << temp, 16 );
236
237 /* Initialize array P[..] and K[..] for the recursion.
238 */
239
240 for (i = 1; i <= 7; i++) K[ i ] = ACF[ i ];
241 for (i = 0; i <= 8; i++) P[ i ] = ACF[ i ];
242
243 /* Compute reflection coefficients
244 */
245 for (n = 1; n <= 8; n++, r++) {
246
247 temp = P[1];
248 temp = GSM_ABS(temp);
249 if (P[0] < temp) {
250 for (i = n; i <= 8; i++) *r++ = 0;
251 return;
252 }
253
254 *r = gsm_div( temp, P[0] );
255
256 assert(*r >= 0);
257 if (P[1] > 0) *r = -*r; /* r[n] = sub(0, r[n]) */
258 assert (*r != MIN_WORD);
259 if (n == 8) return;
260
261 /* Schur recursion
262 */
263 temp = (word)GSM_MULT_R( P[1], *r );
264 P[0] = GSM_ADD( P[0], temp );
265
266 for (m = 1; m <= 8 - n; m++) {
267 temp = (word)GSM_MULT_R( K[ m ], *r );
268 P[m] = GSM_ADD( P[ m+1 ], temp );
269
270 temp = (word)GSM_MULT_R( P[ m+1 ], *r );
271 K[m] = GSM_ADD( K[ m ], temp );
272 }
273 }
274}
SASR
#define SASR(x, by)
Definition: codecs/gsm/inc/private.h:54
GSM_ADD
static word GSM_ADD(longword a, longword b)
Definition: codecs/gsm/inc/private.h:152
P
#define P(protos)
Definition: proto.h:51

References GSM_ABS, GSM_ADD(), GSM_MULT_R, MIN_WORD, P, and SASR.

◆ P2() [2/2]

static void Autocorrelation P2 ( (s, L_ACF)  ,
word *  s,
longword *  L_ACF 
)
static

Definition at line 30 of file lpc.c.

37{
38#ifndef K6OPT
39 register int k, i;
40 word temp;
41#endif
42
43 word smax, scalauto;
44
45#ifdef USE_FLOAT_MUL
46 float float_s[160];
47#endif
48
49 /* Dynamic scaling of the array s[0..159]
50 */
51
52 /* Search for the maximum.
53 */
54#ifndef K6OPT
55 smax = 0;
56 for (k = 0; k <= 159; k++) {
57 temp = GSM_ABS( s[k] );
58 if (temp > smax) smax = temp;
59 }
60#else
61 {
62 longword lmax;
63 lmax = k6maxmin(s,160,NULL);
64 smax = (lmax > MAX_WORD) ? MAX_WORD : lmax;
65 }
66#endif
67 /* Computation of the scaling factor.
68 */
69 if (smax == 0) scalauto = 0;
70 else {
71 assert(smax > 0);
72 scalauto = 4 - gsm_norm( (longword)smax << 16 );/* sub(4,..) */
73 }
74
75 /* Scaling of the array s[0...159]
76 */
77
78 if (scalauto > 0) {
79# ifndef K6OPT
80
81# ifdef USE_FLOAT_MUL
82# define SCALE(n) \
83 case n: for (k = 0; k <= 159; k++) \
84 float_s[k] = (float) \
85 (s[k] = GSM_MULT_R(s[k], 16384 >> (n-1)));\
86 break;
87# else
88# define SCALE(n) \
89 case n: for (k = 0; k <= 159; k++) \
90 s[k] = (word)GSM_MULT_R( s[k], 16384 >> (n-1) );\
91 break;
92# endif /* USE_FLOAT_MUL */
93
94 switch (scalauto) {
95 SCALE(1)
96 SCALE(2)
97 SCALE(3)
98 SCALE(4)
99 }
100# undef SCALE
101
102# else /* K6OPT */
103 k6vsraw(s,160,scalauto);
104# endif
105 }
106# ifdef USE_FLOAT_MUL
107 else for (k = 0; k <= 159; k++) float_s[k] = (float) s[k];
108# endif
109
110 /* Compute the L_ACF[..].
111 */
112#ifndef K6OPT
113 {
114# ifdef USE_FLOAT_MUL
115 register float * sp = float_s;
116 register float sl = *sp;
117
118# define STEP(k) L_ACF[k] += (longword)(sl * sp[ -(k) ]);
119# else
120 word * sp = s;
121 word sl = *sp;
122
123# define STEP(k) L_ACF[k] += ((longword)sl * sp[ -(k) ]);
124# endif
125
126# define NEXTI sl = *++sp
127
128
129 for (k = 9; k--; L_ACF[k] = 0) ;
130
131 STEP (0);
132 NEXTI;
133 STEP(0); STEP(1);
134 NEXTI;
135 STEP(0); STEP(1); STEP(2);
136 NEXTI;
137 STEP(0); STEP(1); STEP(2); STEP(3);
138 NEXTI;
139 STEP(0); STEP(1); STEP(2); STEP(3); STEP(4);
140 NEXTI;
141 STEP(0); STEP(1); STEP(2); STEP(3); STEP(4); STEP(5);
142 NEXTI;
143 STEP(0); STEP(1); STEP(2); STEP(3); STEP(4); STEP(5); STEP(6);
144 NEXTI;
145 STEP(0); STEP(1); STEP(2); STEP(3); STEP(4); STEP(5); STEP(6); STEP(7);
146
147 for (i = 8; i <= 159; i++) {
148
149 NEXTI;
150
151 STEP(0);
152 STEP(1); STEP(2); STEP(3); STEP(4);
153 STEP(5); STEP(6); STEP(7); STEP(8);
154 }
155
156 for (k = 9; k--; L_ACF[k] <<= 1) ;
157
158 }
159
160#else
161 {
162 int k;
163 for (k=0; k<9; k++) {
164 L_ACF[k] = 2*k6iprod(s,s+k,160-k);
165 }
166 }
167#endif
168 /* Rescaling of the array s[0..159]
169 */
170 if (scalauto > 0) {
171 assert(scalauto <= 4);
172#ifndef K6OPT
173 for (k = 160; k--; *s++ <<= scalauto) ;
174# else /* K6OPT */
175 k6vsllw(s,160,scalauto);
176# endif
177 }
178}
MAX_WORD
#define MAX_WORD
Definition: codecs/gsm/inc/private.h:45
longword
long longword
Definition: codecs/gsm/inc/private.h:13
NEXTI
#define NEXTI
SCALE
#define SCALE(n)
NULL
#define NULL
Definition: resample.c:96

References GSM_ABS, MAX_WORD, NEXTI, NULL, SCALE, and STEP.

◆ P3()

void Gsm_LPC_Analysis P3 ( (S, s, LARc)  ,
struct gsm_state *  S,
word *  s,
word *  LARc 
)

Definition at line 357 of file lpc.c.

361{
362 longword L_ACF[9];
363
364#if defined(USE_FLOAT_MUL) && defined(FAST)
365 if (S->fast) Fast_Autocorrelation (s, L_ACF );
366 else
367#endif
368 Autocorrelation (s, L_ACF );
369 Reflection_coefficients (L_ACF, LARc );
370 Transformation_to_Log_Area_Ratios (LARc);
371 Quantization_and_coding (LARc);
372}
S
#define S(e)
LARc
#define LARc

References LARc, and S.

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