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+ i8086 asm optimized implementation of CompareDWord

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git-svn-id: trunk@32039 -
This commit is contained in:
nickysn 2015-10-13 14:51:50 +00:00
parent e388a39e3d
commit 7ed7b090fe
1 changed files with 63 additions and 0 deletions
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63
rtl/i8086/i8086.inc
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@ -370,6 +370,69 @@ end;
{$endif FPC_SYSTEM_HAS_COMPAREWORD}
{$ifndef FPC_SYSTEM_HAS_COMPAREDWORD}
{$define FPC_SYSTEM_HAS_COMPAREDWORD}
function CompareDWord(Const buf1,buf2;len:SizeInt):SizeInt; assembler; nostackframe;
asm
xor ax, ax // initialize ax=0 (it's the result register, we never use it for anything else in this function)
mov bx, sp
mov cx, ss:[bx + 2 + extra_param_offset] // len
jcxz @@Done
cmp cx, 4000h
jb @@NotTooBig
mov cx, 4000h
@@NotTooBig:
shl cx, 1
mov dx, ds // for far data models, backup ds; for near data models, use to initialize es
{$ifdef FPC_X86_DATA_NEAR}
mov es, dx
mov si, ss:[bx + 6 + extra_param_offset] // @buf1
mov di, ss:[bx + 4 + extra_param_offset] // @buf2
{$else FPC_X86_DATA_NEAR}
lds si, ss:[bx + 8 + extra_param_offset] // @buf1
les di, ss:[bx + 4 + extra_param_offset] // @buf2
{$endif FPC_X86_DATA_NEAR}
{$ifdef FPC_ENABLED_CLD}
cld
{$endif FPC_ENABLED_CLD}
repe cmpsw
je @@Equal
// ax is 0
sbb ax, ax
shl ax, 1
inc ax
shr cx, 1
jnc @@Skip
xchg ax, bx
xor ax, ax
cmpsw
je @@hi_equal
// ax is 0
sbb ax, ax
shl ax, 1
inc ax
jmp @@Skip
@@hi_equal:
xchg ax, bx
@@Equal:
// ax is 0
@@Skip:
{$if defined(FPC_X86_DATA_FAR) or defined(FPC_X86_DATA_HUGE)}
mov ds, dx
{$endif}
@@Done:
end;
{$endif FPC_SYSTEM_HAS_COMPAREDWORD}
{$define FPC_SYSTEM_HAS_SPTR}
Function Sptr : Pointer;assembler;nostackframe;
asm