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jeremybenn |
/*
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* (c) Copyright 1986 HEWLETT-PACKARD COMPANY
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*
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* To anyone who acknowledges that this file is provided "AS IS"
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* without any express or implied warranty:
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* permission to use, copy, modify, and distribute this file
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* for any purpose is hereby granted without fee, provided that
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* the above copyright notice and this notice appears in all
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* copies, and that the name of Hewlett-Packard Company not be
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* used in advertising or publicity pertaining to distribution
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* of the software without specific, written prior permission.
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* Hewlett-Packard Company makes no representations about the
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* suitability of this software for any purpose.
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*/
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/* memcmp(s1, s2, n) */
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/* returns integer: < 0 iff s1 lexicographically less than s2 */
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/* > 0 iff s1 lexicographically greater than s2 */
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/* = 0 iff s1 lexicographically equal to s2 */
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/* = 0 iff s1 lexicographically equal to s2 */
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/* quit after n charachters */
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#ifndef _NAMESPACE_CLEAN
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#define NOSECDEF /* prevents _memcmp from becoming primary entry */
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#endif
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#include "DEFS.h"
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#define s1 26
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#define s2 25
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#define tmp1 19
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#define s2word 20
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#define tmp3 21
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#define tmp7 22
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#define s1word 29
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#define save 1
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#define tmp6 23
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#define tmp5 28
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#define count 24
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ENTRY(memcmp)
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combt,<,n r0,count,search /*N <= 0 yields equality */
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b done /**/
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copy 0,ret0 /*return 0 (DELAY SLOT) */
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search: combf,=,n s1,s2,findout /*s1 != s2? */
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b done
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copy 0,ret0 /*return 0 (delay slot) */
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findout:
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comibf,=,n 0,s1,checks1 /*s1 == NULL? */
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ldbs 0(0,s2),ret0 /**/
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b done /*quit */
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sub 0,ret0,ret0 /*ret0 <- -*s2 */
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checks1:
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comibf,=,n 0,s2,checkitout /*s2 == NULL? */
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b done /* quit */
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ldbs 0(0,s1),28 /* return *s1 */
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checkitout:
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extru s2,31,2,tmp1 /* Extract the low two bits of the s2. */
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extru s1,31,2,tmp5 /* Extract the low two bits of the s1 */
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sub,= tmp5,tmp1,tmp3 /* Are s1 & s2 aligned with each other? */
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b not_aligned /* It's more complicated (not_aligned) */
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dep 0,31,2,s1 /* Compute word address of s1 (DELAY SLOT) */
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dep 0,31,2,s2 /* Compute word address of s2 */
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ldwm 4(0,s1),s1word /* get next s1 word s1+=4 */
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combt,= tmp5,r0,skipmask /* skip masking, if we can */
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ldwm 4(0,s2),s2word /* get next s2 word s2+=4 (DELAY SLOT) */
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add tmp5,count,count /* bump count by the number of bytes */
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/* we are going to mask */
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sh3add tmp5,r0,save /* save now has number of bits to mask */
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mtctl save,11
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zvdepi -2,32,save /* load save with proper mask */
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or save,s1word,s1word /* mask s1word (s1) */
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or save,s2word,s2word /* mask s2word (s2) */
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skipmask:
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combt,=,n s1word,s2word,checkN /* We may be done */
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checkbyte:
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extru s1word,7,8,tmp3 /* get first byte (character) */
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ckbyte2: extru s2word,7,8,tmp7 /* get first byte (character) */
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combf,= tmp3,tmp7,done /* quit if first byte is not equal */
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sub tmp3,tmp7,ret0 /* return difference (delay slot) */
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addibt,<=,n -1,count,done /* have we checked N chars? ret0 == 0 */
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extru s1word,15,8,tmp3 /* get second byte (character) */
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extru s2word,15,8,tmp7 /* get second byte (character) */
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combf,= tmp3,tmp7,done /* quit if second byte is not equal */
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sub tmp3,tmp7,ret0 /* return difference (delay slot) */
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addibt,<=,n -1,count,done /* have we checked N chars? */
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extru s1word,23,8,tmp3 /* get third byte (character) */
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extru s2word,23,8,tmp7 /* get third byte (character) */
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combf,= tmp3,tmp7,done /* done if third byte is not equal */
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sub tmp3,tmp7,ret0 /* return difference (delay slot) */
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addibt,<=,n -1,count,done /* have we checked N chars? */
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extru s1word,31,8,tmp3 /* get last byte (character) */
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extru s2word,31,8,tmp7 /* get last byte (character) */
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b done /* if we reach this point we know that */
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sub tmp3,tmp7,ret0 /* the last character in the word is */
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/* where the difference is, so return */
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/* the difference and we're outta here */
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checkN:
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addibt,<=,n -4,count,zero /* have we checked N chars? */
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ldwm 4(0,s2),s2word /* get next s2 word s2+=4 */
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b skipmask /* keep checking */
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ldwm 4(0,s1),s1word /* get next s1 word s1+=4 */
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not_aligned:
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dep r0,31,2,s2 /* Compute word address of s2 */
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combt,<,n r0,tmp3,shifts1 /* Do we shift s1 or s2 */
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sh3add tmp3,r0,tmp3 /* eight bits per byte so mul by 8 */
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ldwm 4(0,s1),s1word /* get first word of s1 */
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ldwm 4(0,s2),s2word /* get first word or s2 */
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combt,=,n r0,tmp5,masks2 /* Do we need to mask beginning of s1 */
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add tmp5,count,count /* bump count by the number of bytes */
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/* we are going to mask */
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sh3add tmp5,r0,save /* save now has number of bits to mask */
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mtctl save,11
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zvdepi -2,32,save /* load save with proper mask */
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or save,s1word,s1word /**/
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masks2: sh3add tmp1,r0,save /* save now has number of bits to mask */
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mtctl save,11
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zvdepi -2,32,save /* load save with proper mask */
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or save,s2word,s2word /**/
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subi 4,tmp1,tmp1 /* tmp1 now has the number of byte that */
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/* are valid in s2word before the vshd */
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mtctl tmp3,11 /* Move shift amount to CR11 */
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more: combt,<=,n count,tmp1,chunk1 /* Can we do the vshd? */
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ldwm 4(0,s2),tmp7 /* load second word to enable us to shift */
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vshd s2word,tmp7,s2word /**/
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combf,=,n s1word,s2word,ckbyte2 /**/
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extru s1word,7,8,tmp3 /* get first byte (DELAY SLOT) */
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addibt,<=,n -4,count,zero /* have we checked N chars? */
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copy tmp7,s2word /**/
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b more /* keep checking */
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ldwm 4(0,s1),s1word /* get next s1 (DELAY SLOT) */
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chunk1:
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vshd s2word,r0,s2word /* do an arithmetic shift left to position data */
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b ckbyte2 /**/
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extru s1word,7,8,tmp3 /**/
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shifts1:
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sh3add tmp3,r0,tmp3 /* eight bits per byte so mul by 8 */
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sub r0,tmp3,tmp3 /* Get negative value for left shift */
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dep r0,31,2,s2 /* Compute word address of s2 */
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ldwm 4(0,s2),s2word /* get first word of s2 */
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ldwm 4(0,s1),s1word /* get first word or s1 */
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combt,=,n r0,tmp1,masks1 /*Do we need to mask beginning of s2 */
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add tmp1,count,count /*bump count by the number of bytes */
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/* we are going to mask */
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sh3add tmp1,r0,save /*save now has number of bits to mask */
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mtctl save,11
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zvdepi -2,32,save /*load save with proper mask */
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or save,s2word,s2word /**/
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masks1: sh3add tmp5,r0,save /*save now has number of bits to mask */
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mtctl save,11
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zvdepi -2,32,save /*load save with proper mask */
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or save,s1word,s1word /**/
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subi 4,tmp5,tmp5 /*tmp5 now has the number of byte that */
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/*are valid in s1word before the vshd */
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mtctl tmp3,11 /*Move shift amount to CR11 */
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more1: combt,<=,n count,tmp5,chunk2 /*Can we do the vshd? */
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ldwm 4(0,s1),tmp7 /*load second word to enable us to shift */
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vshd s1word,tmp7,s1word /**/
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combf,=,n s2word,s1word,ckbyte2 /**/
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extru s1word,7,8,tmp3 /*get first byte (DELAY SLOT) */
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addibt,<=,n -4,count,zero /*have we checked N chars? */
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copy tmp7,s1word /**/
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b more1 /*keep checking */
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ldwm 4(0,s2),s2word /*get next s2 (DELAY SLOT) */
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chunk2:
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vshd s1word,r0,s1word /**/
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b ckbyte2 /**/
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extru s1word,7,8,tmp3 /**/
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zero: copy r0,ret0
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done:
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EXIT(memcmp)
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