2 * Copyright (c) 1993,94 Winning Strategies, Inc.
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6 * modification, are permitted provided that the following conditions
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15 * This product includes software developed by Winning Strategies, Inc.
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31 #include <machine/asm.h>
32 __FBSDID("$FreeBSD$");
36 * return an integer greater than, equal to, or less than 0,
37 * according as the first n characters of string s1 is greater
38 * than, equal to, or less than the string s2.
40 * %eax - pointer to s1
41 * %ecx - pointer to s2
45 * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
49 * I've unrolled the loop eight times: large enough to make a
50 * significant difference, and small enough not to totally trash the
53 * TODO: change all the jz's back to je for consistency.
62 jmp L2 /* Jump into the loop! */
68 L2: jz L4 /* strings are equal */
76 * XXX it might be best to move the next 4 instructions to the end of the
77 * unrolled part of the loop. The unrolled part would then be
78 * movb n(%eax),%bl; testb %bl, %bl; je L3; cmpb n(%ecx); jne L3
80 * movb n(%eax),%bl; cmpb n(%ecx); jne L3; testb %bl,%bl; je return_0
81 * for n = 0, 1, ..., 8. The end of the loop would be
82 * L1: addl $8,%eax; addl $8,%ecx; subl $8,%edx; cmpl $8,%edx; jae Lx
83 * where residual counts of 0 to 7 are handled at Lx. However, this would
84 * be slower for short strings. Cache effects are probably not so
85 * important because we are only handling a byte at a time.
158 L3: movzbl (%eax),%eax /* unsigned comparison */