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Improve accuracy of division in calcSubbandGain(). 

am: 69a5c189ad

Change-Id: I2bc889856aa9b066ba5d1c2043a6864b2455733f
This commit is contained in:
Fraunhofer IIS FDK 2019-05-15 23:05:02 -07:00 committed by android-build-merger
parent ced1a601f0 69a5c189ad
commit c9fbf5a360
1 changed files with 10 additions and 2 deletions
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12
libSBRdec/src/env_calc.cpp
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@ -1,7 +1,7 @@
/* -----------------------------------------------------------------------------
Software License for The Fraunhofer FDK AAC Codec Library for Android
© Copyright 1995 - 2018 Fraunhofer-Gesellschaft zur Förderung der angewandten
© Copyright 1995 - 2019 Fraunhofer-Gesellschaft zur Förderung der angewandten
Forschung e.V. All rights reserved.
1. INTRODUCTION
@ -2325,7 +2325,15 @@ static void calcSubbandGain(
}
/* gain = nrgRef / B */
FDK_divide_MantExp(nrgRef, nrgRef_e, b, b_e, ptrNrgGain, ptrNrgGain_e);
INT result_exp = 0;
*ptrNrgGain = fDivNorm(nrgRef, b, &result_exp);
*ptrNrgGain_e = (SCHAR)result_exp + (nrgRef_e - b_e);
/* There could be a one bit diffs. This is important to compensate,
because later in the code values are compared by exponent only. */
int headroom = CountLeadingBits(*ptrNrgGain);
*ptrNrgGain <<= headroom;
*ptrNrgGain_e -= headroom;
}
}