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ac3dsp: do not use pshufb in ac3_extract_exponents_ssse3()
We need to do unsigned saturation in order to cover the corner case when the absolute coefficient value is 16777215 (the maximum value). Fixes Bug #216
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@ -35,7 +35,6 @@ pw_bap_mul2: dw 5, 7, 0, 7, 5, 7, 0, 7
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; used in ff_ac3_extract_exponents()
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pd_1: times 4 dd 1
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pd_151: times 4 dd 151
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pb_shuf_4dwb: db 0, 4, 8, 12
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SECTION .text
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@ -404,15 +403,12 @@ cglobal ac3_extract_exponents_3dnow, 3,3,0, exp, coef, len
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%endif
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%macro AC3_EXTRACT_EXPONENTS 1
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cglobal ac3_extract_exponents_%1, 3,3,5, exp, coef, len
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cglobal ac3_extract_exponents_%1, 3,3,4, exp, coef, len
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add expq, lenq
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lea coefq, [coefq+4*lenq]
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neg lenq
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mova m2, [pd_1]
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mova m3, [pd_151]
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%ifidn %1, ssse3 ;
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movd m4, [pb_shuf_4dwb]
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%endif
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.loop:
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; move 4 32-bit coefs to xmm0
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mova m0, [coefq+4*lenq]
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@ -426,12 +422,11 @@ cglobal ac3_extract_exponents_%1, 3,3,5, exp, coef, len
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mova m0, m3
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psubd m0, m1
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; move the lowest byte in each of 4 dwords to the low dword
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%ifidn %1, ssse3
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pshufb m0, m4
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%else
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; NOTE: We cannot just extract the low bytes with pshufb because the dword
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; result for 16777215 is -1 due to float inaccuracy. Using packuswb
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; clips this to 0, which is the correct exponent.
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packssdw m0, m0
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packuswb m0, m0
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%endif
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movd [expq+lenq], m0
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add lenq, 4
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