Multiply in 64 bits to avoid overflow

webrtc/modules/audio_coding/codecs/isac/fix/source/entropy_coding.c

 /*
  *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 /*
  * entropy_coding.c
  *
  * This file contains all functions used to arithmetically
  * encode the iSAC bistream.
  *
  */
 
 #include <stddef.h>
 
 #include "arith_routins.h"
 #include "spectrum_ar_model_tables.h"
 #include "pitch_gain_tables.h"
 #include "pitch_lag_tables.h"
 #include "entropy_coding.h"
 #include "lpc_tables.h"
 #include "settings.h"
 #include "signal_processing_library.h"
+#include "webrtc/base/checks.h"
 
 /*
  * Eenumerations for arguments to functions WebRtcIsacfix_MatrixProduct1()
  * and WebRtcIsacfix_MatrixProduct2().
 */
 
 enum matrix_index_factor {
   kTIndexFactor1 = 1,
   kTIndexFactor2 = 2,
   kTIndexFactor3 = SUBFRAMES,
@@ skipping 184 matching lines @@
     for (n = k; n < AR_ORDER+1; n++)
       sum += WEBRTC_SPL_MUL(ARCoefQ12[n-k], ARCoefQ12[n]);  /* Q24 */
     sum >>= 15;
     CorrQ11[k] = (sum * tmpGain + round) >> shftVal;
   }
   sum = CorrQ11[0] << 7;
   for (n = 0; n < FRAMESAMPLES/8; n++)
     CurveQ16[n] = sum;
 
   for (k = 1; k < AR_ORDER; k += 2) {
-    for (n = 0; n < FRAMESAMPLES/8; n++)
-      CurveQ16[n] += (WebRtcIsacfix_kCos[k][n] * CorrQ11[k + 1] + 2) >> 2;
+    for (n = 0; n < FRAMESAMPLES/8; n++) {
+      const int64_t p =
+          (WebRtcIsacfix_kCos[k][n] * (int64_t)CorrQ11[k + 1] + 2) >> 2;
+      RTC_DCHECK_EQ(p, (int32_t)p);  // p fits in 32 bits
+      CurveQ16[n] += (int32_t)p;
+    }
   }
 
   CS_ptrQ9 = WebRtcIsacfix_kCos[0];
 
   /* If CorrQ11[1] too large we avoid getting overflow in the calculation by shifting */
   sh=WebRtcSpl_NormW32(CorrQ11[1]);
   if (CorrQ11[1]==0) /* Use next correlation */
     sh=WebRtcSpl_NormW32(CorrQ11[2]);
 
   if (sh<9)
     shftVal = 9 - sh;
   else
     shftVal = 0;
 
   for (n = 0; n < FRAMESAMPLES/8; n++)
     diffQ16[n] = (CS_ptrQ9[n] * (CorrQ11[1] >> shftVal) + 2) >> 2;
   for (k = 2; k < AR_ORDER; k += 2) {
     CS_ptrQ9 = WebRtcIsacfix_kCos[k];
     for (n = 0; n < FRAMESAMPLES/8; n++)
       diffQ16[n] += (CS_ptrQ9[n] * (CorrQ11[k + 1] >> shftVal) + 2) >> 2;
   }
 
   for (k=0; k<FRAMESAMPLES/8; k++) {
     int32_t diff_q16 = diffQ16[k] * (1 << shftVal);
-    CurveQ16[FRAMESAMPLES / 4 - 1 - k] = CurveQ16[k] - diff_q16;
-    CurveQ16[k] += diff_q16;
+    CurveQ16[FRAMESAMPLES / 4 - 1 - k] =
+        WebRtcSpl_SubSatW32(CurveQ16[k], diff_q16);
+    CurveQ16[k] = WebRtcSpl_AddSatW32(CurveQ16[k], diff_q16);
   }
 }
 
 static void CalcRootInvArSpec(const int16_t *ARCoefQ12,
                               const int32_t gainQ10,
                               uint16_t *CurveQ8)
 {
   int32_t CorrQ11[AR_ORDER+1];
   int32_t sum, tmpGain;
   int32_t summQ16[FRAMESAMPLES/8];
@@ skipping 214 matching lines @@
   len = WebRtcIsacfix_DecLogisticMulti2(data, streamdata, invARSpec2_Q16, (int16_t)FRAMESAMPLES);
 
   if (len<1)
     return -ISAC_RANGE_ERROR_DECODE_SPECTRUM;
 
   /* subtract dither and scale down spectral samples with low SNR */
   if (AvgPitchGain_Q12 <= 614)
   {
     for (k = 0; k < FRAMESAMPLES; k += 4)
     {
-      gainQ10 = WebRtcSpl_DivW32W16ResW16(30 << 10,
-          (int16_t)((uint32_t)(invARSpec2_Q16[k >> 2] + 2195456) >> 16));
+      gainQ10 = WebRtcSpl_DivW32W16ResW16(
+          30 << 10, (int16_t)((uint32_t)(WebRtcSpl_AddSatW32(
+                                  invARSpec2_Q16[k >> 2], 2195456)) >>
+                              16));
       *frQ7++ = (int16_t)((data[k] * gainQ10 + 512) >> 10);
       *fiQ7++ = (int16_t)((data[k + 1] * gainQ10 + 512) >> 10);
       *frQ7++ = (int16_t)((data[k + 2] * gainQ10 + 512) >> 10);
       *fiQ7++ = (int16_t)((data[k + 3] * gainQ10 + 512) >> 10);
     }
   }
   else
   {
     for (k = 0; k < FRAMESAMPLES; k += 4)
     {
-      gainQ10 = WebRtcSpl_DivW32W16ResW16(36 << 10,
-          (int16_t)((uint32_t)(invARSpec2_Q16[k >> 2] + 2654208) >> 16));
+      gainQ10 = WebRtcSpl_DivW32W16ResW16(
+          36 << 10, (int16_t)((uint32_t)(WebRtcSpl_AddSatW32(
+                                  invARSpec2_Q16[k >> 2], 2654208)) >>
+                              16));
       *frQ7++ = (int16_t)((data[k] * gainQ10 + 512) >> 10);
       *fiQ7++ = (int16_t)((data[k + 1] * gainQ10 + 512) >> 10);
       *frQ7++ = (int16_t)((data[k + 2] * gainQ10 + 512) >> 10);
       *fiQ7++ = (int16_t)((data[k + 3] * gainQ10 + 512) >> 10);
     }
   }
 
   return len;
 }
 
@@ skipping 1507 matching lines @@
 
     index_gQQ[k] = pos2QQ + WebRtcIsacfix_kQuantMinGain[k]; //ATTN: ok?
     if (index_gQQ[k] < 0) {
       index_gQQ[k] = 0;
     }
     else if (index_gQQ[k] > WebRtcIsacfix_kMaxIndGain[k]) {
       index_gQQ[k] = WebRtcIsacfix_kMaxIndGain[k];
     }
   }
 }