FreeCalypso > hg > gsm-codec-lib
view libtwamr/mac_32.c @ 581:e2d5cad04cbf
libgsmhr1 RxFE: store CN R0+LPC separately from speech
In the original GSM 06.06 code the ECU for speech mode is entirely
separate from the CN generator, maintaining separate state. (The
main intertie between them is the speech vs CN state variable,
distinguishing between speech and CN BFIs, in addition to the
CN-specific function of distinguishing between initial and update
SIDs.)
In the present RxFE implementation I initially thought that we could
use the same saved_frame buffer for both ECU and CN, overwriting
just the first 4 params (R0 and LPC) when a valid SID comes in.
However, I now realize it was a bad idea: the original code has a
corner case (long sequence of speech-mode BFIs to put the ECU in
state 6, then SID and CN-mode BFIs, then a good speech frame) that
would be broken by that buffer reuse approach. We could eliminate
this corner case by resetting the ECU state when passing through
a CN insertion period, but doing so would needlessly increase
the behavioral diffs between GSM 06.06 and our version.
Solution: use a separate CN-specific buffer for CN R0+LPC parameters,
and match the behavior of GSM 06.06 code in this regard.
| author | Mychaela Falconia <falcon@freecalypso.org> |
|---|---|
| date | Thu, 13 Feb 2025 10:02:45 +0000 |
| parents | 61047a2912a2 |
| children |
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/* ******************************************************************************** * * GSM AMR-NB speech codec R98 Version 7.6.0 December 12, 2001 * R99 Version 3.3.0 * REL-4 Version 4.1.0 * ******************************************************************************** * * File : mac_32.c * Purpose : 32 x 32 and 32 x 16 bit DPF multiy & accumulate * (similar as Mpy_32 and Mpy_32_16 in oper_32b.c) * ******************************************************************************** */ /* ******************************************************************************** * MODULE INCLUDE FILE AND VERSION ID ******************************************************************************** */ #include "namespace.h" #include "mac_32.h" /* ******************************************************************************** * INCLUDE FILES ******************************************************************************** */ #include "typedef.h" #include "basic_op.h" #include "oper_32b.h" #include "no_count.h" /* ******************************************************************************** * PUBLIC PROGRAM CODE ******************************************************************************** */ /***************************************************************************** * Function Mac_32() * * * * Multiply two 32 bit integers (DPF) and accumulate with (normal) 32 bit * * integer. The multiplication result is divided by 2**31 * * * * L_32 = L_32 + (hi1*hi2)<<1 + ( (hi1*lo2)>>15 + (lo1*hi2)>>15 )<<1 * * * * This operation can also be viewed as the multiplication of two Q31 * * number and the result is also in Q31. * * * * Arguments: * * * * hi1 hi part of first number * * lo1 lo part of first number * * hi2 hi part of second number * * lo2 lo part of second number * * * ***************************************************************************** */ Word32 Mac_32 (Word32 L_32, Word16 hi1, Word16 lo1, Word16 hi2, Word16 lo2) { L_32 = L_mac (L_32, hi1, hi2); L_32 = L_mac (L_32, mult (hi1, lo2), 1); L_32 = L_mac (L_32, mult (lo1, hi2), 1); return (L_32); } /***************************************************************************** * Function Mac_32_16() * * * * Multiply a 16 bit integer by a 32 bit (DPF) and accumulate with (normal)* * 32 bit integer. The multiplication result is divided by 2**15 * * * * * * L_32 = L_32 + (hi1*lo2)<<1 + ((lo1*lo2)>>15)<<1 * * * * Arguments: * * * * hi hi part of 32 bit number. * * lo lo part of 32 bit number. * * n 16 bit number. * * * ***************************************************************************** */ Word32 Mac_32_16 (Word32 L_32, Word16 hi, Word16 lo, Word16 n) { L_32 = L_mac (L_32, hi, n); L_32 = L_mac (L_32, mult (lo, n), 1); return (L_32); }