461 lines
10 KiB
C
461 lines
10 KiB
C
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/*
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* Copyright 1992 by Jutta Degener and Carsten Bormann, Technische
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* Universitaet Berlin. See the accompanying file "COPYRIGHT" for
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* details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
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*/
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#include <stdio.h>
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#include <assert.h>
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#include "gsm610_priv.h"
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/* 4.2.13 .. 4.2.17 RPE ENCODING SECTION
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*/
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/* 4.2.13 */
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static void Weighting_filter (
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register int16_t * e, /* signal [-5..0.39.44] IN */
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int16_t * x /* signal [0..39] OUT */
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)
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/*
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* The coefficients of the weighting filter are stored in a table
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* (see table 4.4). The following scaling is used:
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*
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* H[0..10] = integer(real_H [0..10] * 8192) ;
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*/
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{
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/* int16_t wt [50] ; */
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register int32_t L_result ;
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register int k /* , i */ ;
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/* Initialization of a temporary working array wt[0...49]
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*/
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/* for (k = 0 ; k <= 4 ; k++) wt[k] = 0 ;
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* for (k = 5 ; k <= 44 ; k++) wt[k] = *e++;
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* for (k = 45 ; k <= 49 ; k++) wt[k] = 0 ;
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*
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* (e[-5..-1] and e[40..44] are allocated by the caller,
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* are initially zero and are not written anywhere.)
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*/
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e -= 5 ;
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/* Compute the signal x[0..39]
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*/
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for (k = 0 ; k <= 39 ; k++)
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{ L_result = 8192 >> 1 ;
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/* for (i = 0 ; i <= 10 ; i++) {
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* L_temp = GSM_L_MULT(wt[k+i], gsm_H[i]) ;
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* L_result = GSM_L_ADD(L_result, L_temp) ;
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* }
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*/
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#undef STEP
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#define STEP(i, H) (e [k + i] * (int32_t) H)
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/* Every one of these multiplications is done twice --
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* but I don't see an elegant way to optimize this.
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* Do you?
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*/
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#ifdef STUPID_COMPILER
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L_result += STEP (0, -134) ;
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L_result += STEP (1, -374) ;
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/* + STEP (2, 0) */
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L_result += STEP (3, 2054) ;
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L_result += STEP (4, 5741) ;
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L_result += STEP (5, 8192) ;
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L_result += STEP (6, 5741) ;
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L_result += STEP (7, 2054) ;
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/* + STEP (8, 0) */
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L_result += STEP (9, -374) ;
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L_result += STEP (10, -134) ;
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#else
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L_result += STEP (0, -134)
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+ STEP (1, -374)
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/* + STEP (2, 0) */
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+ STEP (3, 2054)
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+ STEP (4, 5741)
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+ STEP (5, 8192)
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+ STEP (6, 5741)
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+ STEP (7, 2054)
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/* + STEP (8, 0) */
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+ STEP (9, -374)
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+ STEP (10, -134) ;
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#endif
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/* L_result = GSM_L_ADD(L_result, L_result) ; (* scaling(x2) *)
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* L_result = GSM_L_ADD(L_result, L_result) ; (* scaling(x4) *)
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*
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* x[k] = SASR(L_result, 16) ;
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*/
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/* 2 adds vs. >>16 => 14, minus one shift to compensate for
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* those we lost when replacing L_MULT by '*'.
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*/
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L_result = SASR_L (L_result, 13) ;
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x [k] = (L_result < MIN_WORD ? MIN_WORD
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: (L_result > MAX_WORD ? MAX_WORD : L_result)) ;
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}
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}
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/* 4.2.14 */
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static void RPE_grid_selection (
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int16_t * x, /* [0..39] IN */
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int16_t * xM, /* [0..12] OUT */
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int16_t * Mc_out /* OUT */
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)
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/*
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* The signal x[0..39] is used to select the RPE grid which is
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* represented by Mc.
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*/
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{
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register int i ;
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register int32_t L_result, L_temp ;
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int32_t EM ; /* xxx should be L_EM? */
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int16_t Mc ;
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int32_t L_common_0_3 ;
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EM = 0 ;
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Mc = 0 ;
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/* for (m = 0 ; m <= 3 ; m++) {
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* L_result = 0 ;
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*
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*
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* for (i = 0 ; i <= 12 ; i++) {
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*
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* temp1 = SASR_W (x[m + 3*i], 2) ;
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*
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* assert (temp1 != MIN_WORD) ;
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*
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* L_temp = GSM_L_MULT(temp1, temp1) ;
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* L_result = GSM_L_ADD(L_temp, L_result) ;
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* }
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*
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* if (L_result > EM) {
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* Mc = m ;
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* EM = L_result ;
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* }
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* }
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*/
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#undef STEP
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#define STEP(m, i) L_temp = SASR_W (x [m + 3 * i], 2) ; \
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L_result += L_temp * L_temp ;
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/* common part of 0 and 3 */
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L_result = 0 ;
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STEP (0, 1) ; STEP (0, 2) ; STEP (0, 3) ; STEP (0, 4) ;
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STEP (0, 5) ; STEP (0, 6) ; STEP (0, 7) ; STEP (0, 8) ;
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STEP (0, 9) ; STEP (0, 10) ; STEP (0, 11) ; STEP (0, 12) ;
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L_common_0_3 = L_result ;
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/* i = 0 */
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STEP (0, 0) ;
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L_result <<= 1 ; /* implicit in L_MULT */
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EM = L_result ;
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/* i = 1 */
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L_result = 0 ;
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STEP (1, 0) ;
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STEP (1, 1) ; STEP (1, 2) ; STEP (1, 3) ; STEP (1, 4) ;
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STEP (1, 5) ; STEP (1, 6) ; STEP (1, 7) ; STEP (1, 8) ;
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STEP (1, 9) ; STEP (1, 10) ; STEP (1, 11) ; STEP (1, 12) ;
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L_result <<= 1 ;
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if (L_result > EM)
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{ Mc = 1 ;
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EM = L_result ;
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}
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/* i = 2 */
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L_result = 0 ;
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STEP (2, 0) ;
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STEP (2, 1) ; STEP (2, 2) ; STEP (2, 3) ; STEP (2, 4) ;
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STEP (2, 5) ; STEP (2, 6) ; STEP (2, 7) ; STEP (2, 8) ;
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STEP (2, 9) ; STEP (2, 10) ; STEP (2, 11) ; STEP (2, 12) ;
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L_result <<= 1 ;
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if (L_result > EM)
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{ Mc = 2 ;
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EM = L_result ;
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}
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/* i = 3 */
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L_result = L_common_0_3 ;
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STEP (3, 12) ;
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L_result <<= 1 ;
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if (L_result > EM)
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{ Mc = 3 ;
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EM = L_result ;
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}
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/* Down-sampling by a factor 3 to get the selected xM [0..12]
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* RPE sequence.
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*/
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for (i = 0 ; i <= 12 ; i ++) xM [i] = x [Mc + 3 * i] ;
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*Mc_out = Mc ;
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}
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/* 4.12.15 */
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static void APCM_quantization_xmaxc_to_exp_mant (
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int16_t xmaxc, /* IN */
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int16_t * expon_out, /* OUT */
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int16_t * mant_out) /* OUT */
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{
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int16_t expon, mant ;
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/* Compute expononent and mantissa of the decoded version of xmaxc
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*/
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expon = 0 ;
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if (xmaxc > 15) expon = SASR_W (xmaxc, 3) - 1 ;
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mant = xmaxc - (expon << 3) ;
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if (mant == 0)
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{ expon = -4 ;
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mant = 7 ;
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}
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else
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{ while (mant <= 7)
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{ mant = mant << 1 | 1 ;
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expon-- ;
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}
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mant -= 8 ;
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}
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assert (expon >= -4 && expon <= 6) ;
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assert (mant >= 0 && mant <= 7) ;
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*expon_out = expon ;
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*mant_out = mant ;
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}
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static void APCM_quantization (
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int16_t * xM, /* [0..12] IN */
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int16_t * xMc, /* [0..12] OUT */
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int16_t * mant_out, /* OUT */
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int16_t * expon_out, /* OUT */
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int16_t * xmaxc_out /* OUT */
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)
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{
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int i, itest ;
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int16_t xmax, xmaxc, temp, temp1, temp2 ;
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int16_t expon, mant ;
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/* Find the maximum absolute value xmax of xM [0..12].
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*/
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xmax = 0 ;
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for (i = 0 ; i <= 12 ; i++)
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{ temp = xM [i] ;
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temp = GSM_ABS (temp) ;
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if (temp > xmax) xmax = temp ;
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}
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/* Qantizing and coding of xmax to get xmaxc.
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*/
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expon = 0 ;
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temp = SASR_W (xmax, 9) ;
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itest = 0 ;
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for (i = 0 ; i <= 5 ; i++)
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{ itest |= (temp <= 0) ;
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temp = SASR_W (temp, 1) ;
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assert (expon <= 5) ;
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if (itest == 0) expon++ ; /* expon = add (expon, 1) */
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}
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assert (expon <= 6 && expon >= 0) ;
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temp = expon + 5 ;
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assert (temp <= 11 && temp >= 0) ;
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xmaxc = gsm_add (SASR_W (xmax, temp), (int16_t) (expon << 3)) ;
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/* Quantizing and coding of the xM [0..12] RPE sequence
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* to get the xMc [0..12]
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*/
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APCM_quantization_xmaxc_to_exp_mant (xmaxc, &expon, &mant) ;
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/* This computation uses the fact that the decoded version of xmaxc
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* can be calculated by using the expononent and the mantissa part of
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* xmaxc (logarithmic table).
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* So, this method avoids any division and uses only a scaling
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* of the RPE samples by a function of the expononent. A direct
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* multiplication by the inverse of the mantissa (NRFAC[0..7]
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* found in table 4.5) gives the 3 bit coded version xMc [0..12]
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* of the RPE samples.
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*/
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/* Direct computation of xMc [0..12] using table 4.5
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*/
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assert (expon <= 4096 && expon >= -4096) ;
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assert (mant >= 0 && mant <= 7) ;
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temp1 = 6 - expon ; /* normalization by the expononent */
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temp2 = gsm_NRFAC [mant] ; /* inverse mantissa */
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for (i = 0 ; i <= 12 ; i++)
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{ assert (temp1 >= 0 && temp1 < 16) ;
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temp = arith_shift_left (xM [i], temp1) ;
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temp = GSM_MULT (temp, temp2) ;
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temp = SASR_W (temp, 12) ;
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xMc [i] = temp + 4 ; /* see note below */
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}
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/* NOTE: This equation is used to make all the xMc [i] positive.
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*/
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*mant_out = mant ;
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*expon_out = expon ;
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*xmaxc_out = xmaxc ;
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}
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/* 4.2.16 */
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static void APCM_inverse_quantization (
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register int16_t * xMc, /* [0..12] IN */
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int16_t mant,
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int16_t expon,
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register int16_t * xMp) /* [0..12] OUT */
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/*
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* This part is for decoding the RPE sequence of coded xMc [0..12]
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* samples to obtain the xMp[0..12] array. Table 4.6 is used to get
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* the mantissa of xmaxc (FAC[0..7]).
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*/
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{
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int i ;
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int16_t temp, temp1, temp2, temp3 ;
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assert (mant >= 0 && mant <= 7) ;
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temp1 = gsm_FAC [mant] ; /* see 4.2-15 for mant */
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temp2 = gsm_sub (6, expon) ; /* see 4.2-15 for exp */
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temp3 = gsm_asl (1, gsm_sub (temp2, 1)) ;
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for (i = 13 ; i-- ;)
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{ assert (*xMc <= 7 && *xMc >= 0) ; /* 3 bit unsigned */
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/* temp = gsm_sub (*xMc++ << 1, 7) ; */
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temp = (*xMc++ << 1) - 7 ; /* restore sign */
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assert (temp <= 7 && temp >= -7) ; /* 4 bit signed */
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temp = arith_shift_left (temp, 12) ; /* 16 bit signed */
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temp = GSM_MULT_R (temp1, temp) ;
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temp = GSM_ADD (temp, temp3) ;
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*xMp++ = gsm_asr (temp, temp2) ;
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}
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}
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/* 4.2.17 */
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static void RPE_grid_positioning (
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int16_t Mc, /* grid position IN */
|
||
|
|
register int16_t * xMp, /* [0..12] IN */
|
||
|
|
register int16_t * ep /* [0..39] OUT */
|
||
|
|
)
|
||
|
|
/*
|
||
|
|
* This procedure computes the reconstructed long term residual signal
|
||
|
|
* ep[0..39] for the LTP analysis filter. The inputs are the Mc
|
||
|
|
* which is the grid position selection and the xMp[0..12] decoded
|
||
|
|
* RPE samples which are upsampled by a factor of 3 by inserting zero
|
||
|
|
* values.
|
||
|
|
*/
|
||
|
|
{
|
||
|
|
int i = 13 ;
|
||
|
|
|
||
|
|
assert (0 <= Mc && Mc <= 3) ;
|
||
|
|
|
||
|
|
switch (Mc)
|
||
|
|
{ case 3: *ep++ = 0 ;
|
||
|
|
/* Falls through. */
|
||
|
|
case 2: do
|
||
|
|
{ *ep++ = 0 ;
|
||
|
|
/* Falls through. */
|
||
|
|
case 1: *ep++ = 0 ;
|
||
|
|
/* Falls through. */
|
||
|
|
case 0: *ep++ = *xMp++ ;
|
||
|
|
} while (--i) ;
|
||
|
|
}
|
||
|
|
while (++Mc < 4) *ep++ = 0 ;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* 4.2.18 */
|
||
|
|
|
||
|
|
/* This procedure adds the reconstructed long term residual signal
|
||
|
|
* ep[0..39] to the estimated signal dpp[0..39] from the long term
|
||
|
|
* analysis filter to compute the reconstructed short term residual
|
||
|
|
* signal dp[-40..-1] ; also the reconstructed short term residual
|
||
|
|
* array dp[-120..-41] is updated.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#if 0 /* Has been inlined in code.c */
|
||
|
|
void Gsm_Update_of_reconstructed_short_time_residual_signal (
|
||
|
|
int16_t * dpp, /* [0...39] IN */
|
||
|
|
int16_t * ep, /* [0...39] IN */
|
||
|
|
int16_t * dp) /* [-120...-1] IN/OUT */
|
||
|
|
{
|
||
|
|
int k ;
|
||
|
|
|
||
|
|
for (k = 0 ; k <= 79 ; k++)
|
||
|
|
dp [-120 + k] = dp [-80 + k] ;
|
||
|
|
|
||
|
|
for (k = 0 ; k <= 39 ; k++)
|
||
|
|
dp [-40 + k] = gsm_add (ep [k], dpp [k]) ;
|
||
|
|
}
|
||
|
|
#endif /* Has been inlined in code.c */
|
||
|
|
|
||
|
|
void Gsm_RPE_Encoding (
|
||
|
|
int16_t * e, /* -5..-1][0..39][40..44 IN/OUT */
|
||
|
|
int16_t * xmaxc, /* OUT */
|
||
|
|
int16_t * Mc, /* OUT */
|
||
|
|
int16_t * xMc) /* [0..12] OUT */
|
||
|
|
{
|
||
|
|
int16_t x [40] ;
|
||
|
|
int16_t xM [13], xMp [13] ;
|
||
|
|
int16_t mant, expon ;
|
||
|
|
|
||
|
|
Weighting_filter (e, x) ;
|
||
|
|
RPE_grid_selection (x, xM, Mc) ;
|
||
|
|
|
||
|
|
APCM_quantization (xM, xMc, &mant, &expon, xmaxc) ;
|
||
|
|
APCM_inverse_quantization (xMc, mant, expon, xMp) ;
|
||
|
|
|
||
|
|
RPE_grid_positioning (*Mc, xMp, e) ;
|
||
|
|
|
||
|
|
}
|
||
|
|
|
||
|
|
void Gsm_RPE_Decoding (
|
||
|
|
int16_t xmaxcr,
|
||
|
|
int16_t Mcr,
|
||
|
|
int16_t * xMcr, /* [0..12], 3 bits IN */
|
||
|
|
int16_t * erp /* [0..39] OUT */
|
||
|
|
)
|
||
|
|
{
|
||
|
|
int16_t expon, mant ;
|
||
|
|
int16_t xMp [13] ;
|
||
|
|
|
||
|
|
APCM_quantization_xmaxc_to_exp_mant (xmaxcr, &expon, &mant) ;
|
||
|
|
APCM_inverse_quantization (xMcr, mant, expon, xMp) ;
|
||
|
|
RPE_grid_positioning (Mcr, xMp, erp) ;
|
||
|
|
}
|