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Xiph.Org
aom-rav1e
Commits
c09d8c14
Commit
c09d8c14
authored
May 02, 2011
by
John Koleszar
Committed by
Code Review
May 02, 2011
Browse files
Merge "Fix documentation typos"
parents
a66d8d33
8942f70c
Changes
1
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vp8/common/x86/idctllm_mmx.asm
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c09d8c14
...
...
@@ -14,18 +14,18 @@
; /****************************************************************************
; * Notes:
; *
; * This implementation makes use of 16 bit fixed point verio of two multiply
; * This implementation makes use of 16 bit fixed point ver
s
io
n
of two multiply
; * constants:
; * 1. sqrt(2) * cos (pi/8)
; *
2. sqrt(2) * sin (pi/8)
; * Bec
u
ase the first constant is bigger than 1, to maintain the same 16 bit
; * fixed point pr
r
cision as the second one, we use a trick of
; * 2. sqrt(2) * sin (pi/8)
; * Beca
u
se the first constant is bigger than 1, to maintain the same 16 bit
; * fixed point pr
e
cision as the second one, we use a trick of
; * x * a = x + x*(a-1)
; * so
; * x * sqrt(2) * cos (pi/8) = x + x * (sqrt(2) *cos(pi/8)-1).
; *
; * For
the second constant, bec
u
ase of the 16bit version is 35468, which
; * is bigger than 32768, in signed 16 bit multiply, it become a negative
; * For the second constant, beca
u
se of the 16bit version is 35468, which
; * is bigger than 32768, in signed 16 bit multiply, it become
s
a negative
; * number.
; * (x * (unsigned)35468 >> 16) = x * (signed)35468 >> 16 + x
; *
...
...
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