2635038e5c
This patch includes the required modifications (summarized in common/lib/libc/minix-port.patch) to make the common part of the NetBSD libc to compile and work under Minix.
108 lines
1.8 KiB
ArmAsm
108 lines
1.8 KiB
ArmAsm
/*
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* Written by J.T. Conklin <jtc@acorntoolworks.com>
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* Public domain.
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*/
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#include <machine/asm.h>
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#if defined(LIBC_SCCS)
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RCSID("$NetBSD: strchr.S,v 1.2 2009/07/17 19:37:57 dsl Exp $")
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#endif
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ENTRY(strchr)
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pushl %esi
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pushl %ebx
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movl 12(%esp),%eax
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movzbl 16(%esp),%ecx
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/*
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* Align to word boundary.
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* Consider unrolling loop?
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*/
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.Lalign:
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testb $3,%al
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je .Lword_aligned
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movb (%eax),%bl
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cmpb %cl,%bl
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je .Ldone
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testb %bl,%bl
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je .Lzero
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incl %eax
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jmp .Lalign
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.Lword_aligned:
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/* copy char to all bytes in word */
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movb %cl,%ch
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movl %ecx,%edx
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sall $16,%ecx
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orl %edx,%ecx
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/* Check whether any byte in the word is equal to ch or 0. */
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_ALIGN_TEXT
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.Lloop:
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movl (%eax),%ebx
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addl $4,%eax
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movl %ebx,%esi
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leal -0x01010101(%ebx),%edx
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xorl %ecx,%esi
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subl $0x01010101,%esi
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orl %esi,%edx
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testl $0x80808080,%edx
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je .Lloop
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/*
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* In rare cases, the above loop may exit prematurely. We must
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* return to the loop if none of the bytes in the word match
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* ch or are equal to 0.
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*/
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/*
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* Alignment here avoids a stall on the Athlon, even though
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* it's not a branch target.
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*/
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_ALIGN_TEXT
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cmpb %cl,%bl /* 1st byte == ch? */
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jne 1f
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subl $4,%eax
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jmp .Ldone
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1: testb %bl,%bl /* 1st byte == 0? */
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je .Lzero
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cmpb %cl,%bh /* 2nd byte == ch? */
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jne 1f
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subl $3,%eax
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jmp .Ldone
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1: testb %bh,%bh /* 2nd byte == 0? */
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je .Lzero
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shrl $16,%ebx
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cmpb %cl,%bl /* 3rd byte == ch? */
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jne 1f
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subl $2,%eax
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jmp .Ldone
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1: testb %bl,%bl /* 3rd byte == 0? */
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je .Lzero
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cmpb %cl,%bh /* 4th byte == ch? */
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jne 1f
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decl %eax
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jmp .Ldone
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1: testb %bh,%bh /* 4th byte == 0? */
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jne .Lloop
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.Lzero:
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/* If a ch wasn't found, return 0. */
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xorl %eax,%eax
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.Ldone:
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popl %ebx
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popl %esi
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ret
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#ifdef __minix
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STRONG_ALIAS(_C_LABEL(index),_C_LABEL(strchr))
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#else
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STRONG_ALIAS(index,strchr)
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#endif
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