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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@295 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Mark Spencer
2001-04-24 02:02:21 +00:00
parent ad0aa8091a
commit 3a0a095d15
7 changed files with 205 additions and 68 deletions
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34
codecs/gsm/src/preprocess.c
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@@ -42,11 +42,8 @@ void Gsm_Preprocess P3((S, s, so),
word mp = S->mp;
word s1;
longword L_s2;
longword L_temp;
word msp, lsp;
word SO;
longword ltmp; /* for ADD */
@@ -58,7 +55,8 @@ void Gsm_Preprocess P3((S, s, so),
/* 4.2.1 Downscaling of the input signal
*/
SO = SASR( *s, 3 ) << 2;
/* SO = SASR( *s, 3 ) << 2;*/
SO = SASR( *s, 1 ) & ~3;
s++;
assert (SO >= -0x4000); /* downscaled by */
@@ -80,21 +78,38 @@ void Gsm_Preprocess P3((S, s, so),
assert(s1 != MIN_WORD);
/* SJB Remark: float might be faster than the mess that follows */
/* Compute the recursive part
*/
L_s2 = s1;
L_s2 <<= 15;
/* Execution of a 31 bv 16 bits multiplication
*/
{
word msp, lsp;
longword L_s2;
longword L_temp;
L_s2 = s1;
L_s2 <<= 15;
#ifndef __GNUC__
msp = SASR( L_z2, 15 );
lsp = L_z2-((longword)msp<<15); /* gsm_L_sub(L_z2,(msp<<15)); */
lsp = L_z2 & 0x7fff; /* gsm_L_sub(L_z2,(msp<<15)); */
L_s2 += GSM_MULT_R( lsp, 32735 );
L_temp = (longword)msp * 32735; /* GSM_L_MULT(msp,32735) >> 1;*/
L_z2 = GSM_L_ADD( L_temp, L_s2 );
/* above does L_z2 = L_z2 * 0x7fd5/0x8000 + L_s2 */
#else
L_z2 = ((long long)L_z2*32735 + 0x4000)>>15;
/* alternate (ansi) version of above line does slightly different rounding:
* L_temp = L_z2 >> 9;
* L_temp += L_temp >> 5;
* L_temp = (++L_temp) >> 1;
* L_z2 = L_z2 - L_temp;
*/
L_z2 = GSM_L_ADD(L_z2,L_s2);
#endif
/* Compute sof[k] with rounding
*/
L_temp = GSM_L_ADD( L_z2, 16384 );
@@ -105,6 +120,7 @@ void Gsm_Preprocess P3((S, s, so),
msp = GSM_MULT_R( mp, -28180 );
mp = SASR( L_temp, 15 );
*so++ = GSM_ADD( mp, msp );
}
}
S->z1 = z1;