Hi,
03.10.2012 5:29, luiz americo pereira camara:
[...]
The complete procedure:
{$ASMMODE INTEL}
procedure AlphaBlendLineConstant(Source, Destination: Pointer; Count:
Integer; ConstantAlpha, Bias: Integer);
asm
{$ifdef CPU64}
// RCX contains Source
// RDX contains Destination
// R8D contains Count
// R9D contains ConstantAlpha
// Bias is on the stack
The procedure declaration above is not specific enough for the assembler
block listed below, because
- the size of "integer" generally may vary;
- calling convention generally may vary;
I'd suggest to
- replace "integer" by "longint" or "word", according to what assembler
code expects;
- specify some calling convention according to what assembler code
expects (IIRC in this case it is cdecl but I'm not completely sure).
HTH
Nikolai
//.NOFRAME
// Load XMM3 with the constant alpha value (replicate it for
every component).
// Expand it to word size.
MOVD XMM3, R9D // ConstantAlpha
PUNPCKLWD XMM3, XMM3
PUNPCKLDQ XMM3, XMM3
// Load XMM5 with the bias value.
MOVD XMM5, [Bias]
PUNPCKLWD XMM5, XMM5
PUNPCKLDQ XMM5, XMM5
// Load XMM4 with 128 to allow for saturated biasing.
MOV R10D, 128
MOVD XMM4, R10D
PUNPCKLWD XMM4, XMM4
PUNPCKLDQ XMM4, XMM4
@1: // The pixel loop calculates an entire pixel in one run.
// Note: The pixel byte values are expanded into the higher
bytes of a word due
// to the way unpacking works. We compensate for this
with an extra shift.
MOVD XMM1, DWORD PTR [RCX] // data is unaligned
MOVD XMM2, DWORD PTR [RDX] // data is unaligned
PXOR XMM0, XMM0 // clear source pixel register for
unpacking
PUNPCKLBW XMM0, XMM1{[RCX]} // unpack source pixel byte
values into words
PSRLW XMM0, 8 // move higher bytes to lower bytes
PXOR XMM1, XMM1 // clear target pixel register for
unpacking
PUNPCKLBW XMM1, XMM2{[RDX]} // unpack target pixel byte
values into words
MOVQ XMM2, XMM1 // make a copy of the shifted values,
we need them again
PSRLW XMM1, 8 // move higher bytes to lower bytes
// calculation is: target = (alpha * (source - target) + 256 *
target) / 256
PSUBW XMM0, XMM1 // source - target
PMULLW XMM0, XMM3 // alpha * (source - target)
PADDW XMM0, XMM2 // add target (in shifted form)
PSRLW XMM0, 8 // divide by 256
// Bias is accounted for by conversion of range 0..255 to
-128..127,
// doing a saturated add and convert back to 0..255.
PSUBW XMM0, XMM4
PADDSW XMM0, XMM5
PADDW XMM0, XMM4
PACKUSWB XMM0, XMM0 // convert words to bytes with saturation
MOVD DWORD PTR [RDX], XMM0 // store the result
@3:
ADD RCX, 4
ADD RDX, 4
DEC R8D
JNZ @1
{$endif}
end;
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