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Use one additional bit headroom to prevent signed integer overflow in BuildAdaptiveExcitation().

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Bug: 145666984
Test: atest DecoderTestXheAac ; atest DecoderTestAacDrc
Change-Id: I5c881238562c3d9f7cd8d77a8c52f7231126587f
This commit is contained in:
Fraunhofer IIS FDK 2019-10-29 13:05:02 +01:00 committed by Jean-Michel Trivi
parent 77e652f766
commit 07b5fd9941
1 changed files with 13 additions and 10 deletions
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23
libAACdec/src/usacdec_acelp.cpp
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@ -465,7 +465,9 @@ void BuildAdaptiveExcitation(
/* Note: code[L_SUBFR] and exc2[L_SUBFR] share the same memory!
If exc2[i] is written, code[i] will be destroyed!
*/
#define SF (SF_CODE + SF_GAIN_C + 1 - SF_EXC)
#define SF_HEADROOM (1)
#define SF (SF_CODE + SF_GAIN_C + 1 - SF_EXC - SF_HEADROOM)
#define SF_GAIN_P2 (SF_GAIN_P - SF_HEADROOM)
int i;
FIXP_DBL tmp, cpe, code_smooth_prev, code_smooth;
@ -477,8 +479,8 @@ void BuildAdaptiveExcitation(
cpe = (period_fac >> (2 - SF_PFAC)) + FL2FXCONST_DBL(0.25f);
/* u'(n) */
tmp = fMultDiv2(*exc, gain_pit) << (SF_GAIN_P + 1); /* v(0)*g_p */
*exc++ = tmp + (fMultDiv2(code[0], gain_code) << SF);
tmp = fMultDiv2(*exc, gain_pit) << (SF_GAIN_P2 + 1); /* v(0)*g_p */
*exc++ = (tmp + (fMultDiv2(code[0], gain_code) << SF)) << SF_HEADROOM;
/* u(n) */
code_smooth_prev = fMultDiv2(*code++, gain_code_smoothed)
@ -487,15 +489,15 @@ void BuildAdaptiveExcitation(
code_smooth = fMultDiv2(code_i, gain_code_smoothed) << SF; /* c(1) * g_sc */
tmp += code_smooth_prev; /* tmp = v(0)*g_p + c(0)*g_sc */
cpe_code_smooth = fMultDiv2(cpe, code_smooth);
*exc2++ = tmp - cpe_code_smooth;
*exc2++ = (tmp - cpe_code_smooth) << SF_HEADROOM;
cpe_code_smooth_prev = fMultDiv2(cpe, code_smooth_prev);
i = L_SUBFR - 2;
do /* ARM926: 22 cycles per iteration */
{
/* u'(n) */
tmp = fMultDiv2(*exc, gain_pit) << (SF_GAIN_P + 1);
*exc++ = tmp + (fMultDiv2(code_i, gain_code) << SF);
tmp = fMultDiv2(*exc, gain_pit) << (SF_GAIN_P2 + 1);
*exc++ = (tmp + (fMultDiv2(code_i, gain_code) << SF)) << SF_HEADROOM;
/* u(n) */
tmp += code_smooth; /* += g_sc * c(i) */
tmp -= cpe_code_smooth_prev;
@ -503,16 +505,17 @@ void BuildAdaptiveExcitation(
code_i = *code++;
code_smooth = fMultDiv2(code_i, gain_code_smoothed) << SF;
cpe_code_smooth = fMultDiv2(cpe, code_smooth);
*exc2++ = tmp - cpe_code_smooth; /* tmp - c_pe * g_sc * c(i+1) */
*exc2++ = (tmp - cpe_code_smooth)
<< SF_HEADROOM; /* tmp - c_pe * g_sc * c(i+1) */
} while (--i != 0);
/* u'(n) */
tmp = fMultDiv2(*exc, gain_pit) << (SF_GAIN_P + 1);
*exc = tmp + (fMultDiv2(code_i, gain_code) << SF);
tmp = fMultDiv2(*exc, gain_pit) << (SF_GAIN_P2 + 1);
*exc = (tmp + (fMultDiv2(code_i, gain_code) << SF)) << SF_HEADROOM;
/* u(n) */
tmp += code_smooth;
tmp -= cpe_code_smooth_prev;
*exc2++ = tmp;
*exc2++ = tmp << SF_HEADROOM;
return;
}