diff options
| -rw-r--r-- | rtl/i386/i386.inc | 73 |
1 files changed, 44 insertions, 29 deletions
diff --git a/rtl/i386/i386.inc b/rtl/i386/i386.inc index 0049ed1e0b..5dc8e7b2ae 100644 --- a/rtl/i386/i386.inc +++ b/rtl/i386/i386.inc @@ -418,56 +418,71 @@ end; {$ifndef FPC_SYSTEM_HAS_COMPAREBYTE} {$define FPC_SYSTEM_HAS_COMPAREBYTE} -function CompareByte(Const buf1,buf2;len:SizeInt):SizeInt; assembler; -var - saveesi,saveedi : longint; +function CompareByte(Const buf1,buf2;len:SizeInt):SizeInt; assembler; nostackframe; asm - movl %edi,saveedi - movl %esi,saveesi + cmpl $57,%ecx { empirically determined value on a Core 2 Duo Conroe } + jg .LCmpbyteFull + testl %ecx,%ecx + je .LCmpbyteZero + + pushl %ebx +.LCmpbyteLoop: + movb (%eax),%bl + cmpb (%edx),%bl + leal 1(%eax),%eax + leal 1(%edx),%edx + jne .LCmpbyteExitFast + decl %ecx + jne .LCmpbyteLoop +.LCmpbyteExitFast: + movzbl -1(%edx),%ecx { Compare last position } + movzbl %bl,%eax + subl %ecx,%eax + popl %ebx + ret + +.LCmpbyteZero: + movl $0,%eax + ret + +.LCmpbyteFull: + pushl %esi + pushl %edi cld -{$ifdef REGCALL} movl %eax,%edi movl %edx,%esi movl %ecx,%eax -{$else} - movl buf2,%esi { Load params} - movl buf1,%edi - movl len,%eax -{$endif} - testl %eax,%eax {We address -1(%esi), so we have to deal with len=0} - je .LCmpbyteExit - cmpl $7,%eax {<7 not worth aligning and go through all trouble} - jl .LCmpbyte2 + movl %edi,%ecx { Align on 32bits } - negl %ecx { calc bytes to align (%edi and 3) xor 3= -%edi and 3} + negl %ecx { calc bytes to align (%edi and 3) xor 3= -%edi and 3 } andl $3,%ecx - subl %ecx,%eax { Subtract from number of bytes to go} + subl %ecx,%eax { Subtract from number of bytes to go } orl %ecx,%ecx rep - cmpsb {The actual 32-bit Aligning} + cmpsb { The actual 32-bit Aligning } jne .LCmpbyte3 - movl %eax,%ecx {bytes to do, divide by 4} - andl $3,%eax {remainder} - shrl $2,%ecx {The actual division} - orl %ecx,%ecx {Sets zero flag if ecx=0 -> no cmp} + movl %eax,%ecx { bytes to do, divide by 4 } + andl $3,%eax { remainder } + shrl $2,%ecx { The actual division } + orl %ecx,%ecx { Sets zero flag if ecx=0 -> no cmp } rep cmpsl - je .LCmpbyte2 { All equal? then to the left over bytes} - movl $4,%eax { Not equal. Rescan the last 4 bytes bytewise} + je .LCmpbyte2 { All equal? then to the left over bytes } + movl $4,%eax { Not equal. Rescan the last 4 bytes bytewise } subl %eax,%esi subl %eax,%edi .LCmpbyte2: - movl %eax,%ecx {bytes still to (re)scan} - orl %eax,%eax {prevent disaster in case %eax=0} + movl %eax,%ecx { bytes still to (re)scan } + orl %eax,%eax { prevent disaster in case %eax=0 } rep cmpsb .LCmpbyte3: movzbl -1(%esi),%ecx - movzbl -1(%edi),%eax // Compare failing (or equal) position + movzbl -1(%edi),%eax { Compare failing (or equal) position } subl %ecx,%eax .LCmpbyteExit: - movl saveedi,%edi - movl saveesi,%esi + popl %edi + popl %esi end; {$endif FPC_SYSTEM_HAS_COMPAREBYTE} |