2 * Copyright (c) 1993,94 Winning Strategies, Inc.
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33 #if defined(LIBC_RCS) && !defined(lint)
36 #endif /* LIBC_RCS and not lint */
42 * return an integer greater than, equal to, or less than 0,
43 * according as the first n characters of string s1 is greater
44 * than, equal to, or less than the string s2.
46 * %eax - pointer to s1
47 * %ecx - pointer to s2
51 * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
55 * I've unrolled the loop eight times: large enough to make a
56 * significant difference, and small enough not to totally trash the
59 * TODO: change all the jz's back to je for consistency.
68 jmp L2 /* Jump into the loop! */
74 L2: jz L4 /* strings are equal */
82 * XXX it might be best to move the next 4 instructions to the end of the
83 * unrolled part of the loop. The unrolled part would then be
84 * movb n(%eax),%bl; testb %bl, %bl; je L3; cmpb n(%ecx); jne L3
86 * movb n(%eax),%bl; cmpb n(%ecx); jne L3; testb %bl,%bl; je return_0
87 * for n = 0, 1, ..., 8. The end of the loop would be
88 * L1: addl $8,%eax; addl $8,%ecx; subl $8,%edx; cmpl $8,%edx; jae Lx
89 * where residual counts of 0 to 7 are handled at Lx. However, this would
90 * be slower for short strings. Cache effects are probably not so
91 * important because we are only handling a byte at a time.
164 L3: movzbl (%eax),%eax /* unsigned comparison */