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--- Libc/Libc-763.11/i386/string/strcmp.s
+++ Libc/Libc-262.2.12/i386/string/strcmp.s
@@ -1,7 +1,9 @@
/*
- * Copyright (c) 2005 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
*
* @APPLE_LICENSE_HEADER_START@
+ *
+ * Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved.
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
@@ -20,126 +22,72 @@
*
* @APPLE_LICENSE_HEADER_END@
*/
+.text
+.globl _strcmp
+_strcmp:
+ movl 0x04(%esp),%eax
+ movl 0x08(%esp),%edx
+ jmp L2 /* Jump into the loop! */
-
-// ***************
-// * S T R C M P *
-// ***************
-//
-// int strcmp(const char *s1, const char *s2);
-//
-// We optimize the compare by doing it in parallel, using SSE. This introduces
-// a complication: if we blindly did vector loads from both sides until
-// finding a difference (or 0), we might get a spurious page fault by
-// reading bytes past the difference. To avoid this, we never do a load
-// that crosses a page boundary.
-
- .text
- .globl _strcmp
-
- .align 4
-_strcmp: // int strcmp(const char *s1,const char *s2);
- pushl %esi
- pushl %edi
- movl 12(%esp),%esi // get LHS ptr
- movl 16(%esp),%edi // get RHS ptr
-
-
-// In order to avoid spurious page faults, we loop over:
-//
-// min( bytes_in_LHS_page, bytes_in_RHS_page) >> 4
-//
-// 16-byte chunks. When we near a page end, we have to revert to a byte-by-byte
-// comparison until reaching the next page, then resume the vector comparison.
-// %esi = LHS ptr
-// %edi = RHS ptr
-
-LNextChunk:
- movl %esi,%eax // copy ptrs
- movl %edi,%edx
- andl $4095,%eax // mask down to page offsets
- andl $4095,%edx
- cmpl %eax,%edx // which is bigger?
- cmova %edx,%eax // %eax = max(LHS offset, RHS offset);
- movl $4096,%edx
- subl %eax,%edx // get #bytes to next page crossing
- movl %edx,%eax
- shrl $4,%edx // get #chunks till end of operand or page
- jnz LLoopOverChunks // enter vector loop
- movl %eax,%edx // no chunks...
- jmp LLoopOverBytes // ...so loop over bytes until page end
-
-
-// Loop over bytes.
-// %esi = LHS ptr
-// %edi = RHS ptr
-// %edx = byte count
-
- .align 4,0x90 // align inner loops to optimize I-fetch
-LLoopOverBytes:
- movzb (%esi),%eax // get LHS byte
- movzb (%edi),%ecx // get RHS byte
- inc %esi
- inc %edi
- testl %eax,%eax // 0?
- jz LExit0 // yes, we're done
- subl %ecx,%eax // compare them
- jnz LExit // done if not equal
- dec %edx // more to go?
- jnz LLoopOverBytes
-
- jmp LNextChunk // we've come to end of page
-
-
-// Loop over 16-byte chunks.
-// %esi = LHS ptr
-// %edi = RHS ptr
-// %edx = chunk count
-
- .align 4,0x90 // align inner loops to optimize I-fetch
-LLoopOverChunks:
- movdqu (%esi),%xmm1 // get LHS
- movdqu (%edi),%xmm2 // get RHS
- pxor %xmm0,%xmm0 // get some 0s in the shadow of the loads
- addl $16,%esi
- pcmpeqb %xmm1,%xmm2 // compare LHS to RHS
- pcmpeqb %xmm1,%xmm0 // compare LHS to 0s
- addl $16,%edi
- pmovmskb %xmm2,%eax // get result mask for comparison of LHS and RHS
- pmovmskb %xmm0,%ecx // get result mask for 0 check
- xorl $0xFFFF,%eax // complement compare mask so 1 means "not equal"
- orl %ecx,%eax // combine the masks and check for 1-bits
- jnz LFoundDiffOr0 // we found differing bytes or a 0-byte
- dec %edx // more to go?
- jnz LLoopOverChunks
-
- jmp LNextChunk // compare up to next page boundary
-
-
-// Found a zero and/or a difference in vector compare.
-// %esi = LHS ptr, already advanced by 16
-// %edi = RHS ptr, already advanced by 16
-// %eax = bit n set if bytes n differed or were 0
-
-LFoundDiffOr0:
- bsf %eax,%edx // which byte differed or was 0?
- subl $16,%esi // point to start of vectors while we wait for bit scan
- subl $16,%edi
- movzb (%esi,%edx),%eax // get LHS byte
- movzb (%edi,%edx),%ecx // get RHS byte
- subl %ecx,%eax // compute difference (ie, return value)
- popl %edi
- popl %esi
- ret
-
-
-// Found a zero and/or difference in byte loop.
-// %eax = LHS byte
-// %ecx = RHS byte
-
-LExit0:
- subl %ecx,%eax // compute difference (ie, return value)
-LExit: // here with difference already in %eax
- popl %edi
- popl %esi
- ret
+ .align 2,0x90
+L1: incl %eax
+ incl %edx
+L2: movb (%eax),%cl
+ testb %cl,%cl /* null terminator??? */
+ jz L3
+ cmpb %cl,(%edx) /* chars match??? */
+ jne L3
+ incl %eax
+ incl %edx
+ movb (%eax),%cl
+ testb %cl,%cl
+ jz L3
+ cmpb %cl,(%edx)
+ jne L3
+ incl %eax
+ incl %edx
+ movb (%eax),%cl
+ testb %cl,%cl
+ jz L3
+ cmpb %cl,(%edx)
+ jne L3
+ incl %eax
+ incl %edx
+ movb (%eax),%cl
+ testb %cl,%cl
+ jz L3
+ cmpb %cl,(%edx)
+ jne L3
+ incl %eax
+ incl %edx
+ movb (%eax),%cl
+ testb %cl,%cl
+ jz L3
+ cmpb %cl,(%edx)
+ jne L3
+ incl %eax
+ incl %edx
+ movb (%eax),%cl
+ testb %cl,%cl
+ jz L3
+ cmpb %cl,(%edx)
+ jne L3
+ incl %eax
+ incl %edx
+ movb (%eax),%cl
+ testb %cl,%cl
+ jz L3
+ cmpb %cl,(%edx)
+ jne L3
+ incl %eax
+ incl %edx
+ movb (%eax),%cl
+ testb %cl,%cl
+ jz L3
+ cmpb %cl,(%edx)
+ je L1
+ .align 2, 0x90
+L3: movzbl (%eax),%eax /* unsigned comparison */
+ movzbl (%edx),%edx
+ subl %edx,%eax
+ ret