2 * Copyright (c) 1993,94 Winning Strategies, Inc.
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11 * notice, this list of conditions and the following disclaimer in the
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14 * must display the following acknowledgement:
15 * This product includes software developed by Winning Strategies, Inc.
16 * 4. The name of the author may not be used to endorse or promote products
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30 * $FreeBSD: src/lib/libc/i386/string/strncmp.S,v 1.6 1999/08/27 23:59:35 peter Exp $
31 * $DragonFly: src/lib/libcr/i386/string/Attic/strncmp.S,v 1.2 2003/06/17 04:26:43 dillon Exp $
33 * $FreeBSD: src/lib/libc/i386/string/strncmp.S,v 1.6 1999/08/27 23:59:35 peter Exp $
40 * return an integer greater than, equal to, or less than 0,
41 * according as the first n characters of string s1 is greater
42 * than, equal to, or less than the string s2.
44 * %eax - pointer to s1
45 * %ecx - pointer to s2
49 * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
53 * I've unrolled the loop eight times: large enough to make a
54 * significant difference, and small enough not to totally trash the
57 * TODO: change all the jz's back to je for consistency.
66 jmp L2 /* Jump into the loop! */
72 L2: jz L4 /* strings are equal */
80 * XXX it might be best to move the next 4 instructions to the end of the
81 * unrolled part of the loop. The unrolled part would then be
82 * movb n(%eax),%bl; testb %bl, %bl; je L3; cmpb n(%ecx); jne L3
84 * movb n(%eax),%bl; cmpb n(%ecx); jne L3; testb %bl,%bl; je return_0
85 * for n = 0, 1, ..., 8. The end of the loop would be
86 * L1: addl $8,%eax; addl $8,%ecx; subl $8,%edx; cmpl $8,%edx; jae Lx
87 * where residual counts of 0 to 7 are handled at Lx. However, this would
88 * be slower for short strings. Cache effects are probably not so
89 * important because we are only handling a byte at a time.
162 L3: movzbl (%eax),%eax /* unsigned comparison */