Thread View: alt.comp.lang.delphi
1 messages
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Started by Anonymous
Sun, 22 Aug 2004 02:01
Function SUM for arrays of type Single?
Author: Anonymous
Date: Sun, 22 Aug 2004 02:01
Date: Sun, 22 Aug 2004 02:01
40 lines
2857 bytes
2857 bytes
To make a long story short: the following is the delphi SUM function for
arrays of Doubles. Any ideas how to re-code this to work with an array of
Singles? (*other* than simply writing a non-asm delphi routine...)
function SUM(const Data: array of Double): Extended;
asm // IN: EAX = ptr to Data, EDX = High(Data) = Count - 1
// Uses 4 accumulators to minimize read-after-write delays and loop
overhead
// 5 clocks per loop, 4 items per loop = 1.2 clocks per item
FLDZ
MOV ECX, EDX
FLD ST(0)
AND EDX, not 3
FLD ST(0)
AND ECX, 3
FLD ST(0)
SHL EDX, 3 // count * sizeof(Double) = count * 8
JMP @Vector.Pointer[ECX*4]
@Vector:
DD @@1
DD @@2
DD @@3
DD @@4
@@4: FADD qword ptr [EAX+EDX+24] // 1
FXCH ST(3) // 0
@@3: FADD qword ptr [EAX+EDX+16] // 1
FXCH ST(2) // 0
@@2: FADD qword ptr [EAX+EDX+8] // 1
FXCH ST(1) // 0
@@1: FADD qword ptr [EAX+EDX] // 1
FXCH ST(2) // 0
SUB EDX, 32
JNS @@4
FADDP ST(3),ST // ST(3) := ST + ST(3); Pop ST
FADD // ST(1) := ST + ST(1); Pop ST
FADD // ST(1) := ST + ST(1); Pop ST
FWAIT
end;
Thanks in advance.
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