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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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/*
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strcmp
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Jerry Huck
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Edgar Circenis
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*/
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/*
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* strcmp(s1, s2)
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*
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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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*/
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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 23
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#define save 1
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#define tmp6 24
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#define tmp5 28
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ENTRY(strcmp)
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comb,=,n s1,s2,samestring
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comib,=,n 0,s1,s1isnull
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comib,=,n 0,s2,s2isnull
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/* Hope for word alignment. Pick up low two bits of each adress */
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extru,<> s1,31,2,tmp1
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ldwm 4(s1),s1word
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dep,= s2,29,2,tmp1
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b,n case_analysis
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/* Start looping until null is found in s1 or they mis-compare */
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loop:
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ldwm 4(s2),s2word
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loop_plus:
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uxor,nbz s1word,r0,r0 /* Null in this? */
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b,n nullins1
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comb,=,n s1word,s2word,loop
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ldwm 4(s1),s1word
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/* The words do not compare equal and s1 does not have a null.
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Need to treat words as unsigned and generate either a positive
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or negative return value */
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wordcomparereturn:
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comclr,>> s1word,s2word,ret0 /*Set ret0 to 0 and skip if greater*/
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ldi -2,ret0 /*Set ret0 to -2 when less */
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bv r0(rp)
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addi 1,ret0,ret0 /*Fix return value to be -1 or +1 */
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/* s1 has a null. s2 has not been checked. */
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nullins1:
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/*If s2 has no nulls this is simple, but assume that it might
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and fix up s1 to allow the word comparision to work by
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scanning s1 and duplicating all the bytes in s2 below that byte into
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the remainder of s1. A remainder only exists if the zero byte
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is found in the upper three bytes */
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extru,<> s1word,7,8,r0 /*in the first byte? */
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dep,tr s2word,31,24,s1word /*copy low 3 bytes of *s2 into *s1 */
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extru,<> s1word,15,8,r0 /*in the second byte? */
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dep,tr s2word,31,16,s1word /*copy low 2 bytes of *s2 into *s1 */
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extru,<> s1word,23,8,r0 /*in the third byte? */
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dep s2word,31,8,s1word /*copy low 1 byte of *s2 into *s1 */
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/* Do the normal unsigned compare and return */
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comclr,<> s1word,s2word,ret0 /*Set ret0 to 0 and skip if not equal */
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bv,n r0(rp)
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comclr,>> s1word,s2word,ret0 /*Set ret0 to 0 and skip if greater*/
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ldi -2,ret0 /*Set ret0 to -2 when less */
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bv r0(rp)
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addi 1,ret0,ret0 /*Fix return value to be -1 or +1 */
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/* s1 and s2 are the same string and therefore equal */
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samestring:
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bv r0(rp)
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copy r0,ret0
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/* s1 is null. Treat as string of nulls. Therefore return
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the negative of s2's first byte. s2 cannot be zero. */
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s1isnull:
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ldbs 0(0,s2),ret0
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bv r0(rp)
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sub 0,ret0,ret0
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/* s2 is null. Treat as string of nulls. Therefore return
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s1's first byte. s1 cannot be zero. */
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s2isnull:
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bv r0(rp)
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ldbs 0(0,s1),ret0
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case_analysis:
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blr tmp1,r0
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nop
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/*
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Case statement for non-aligned cases (we've already
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checked the aligned case.
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NOTE: for non-aligned cases, the absolute shift value
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gets loaded into tmp3.
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*/
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/* S2 S1 */
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nop /* 00 00 can't happen */
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nop
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b shifts2 /* 00 01 */
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ldi 8,tmp3 /* load shift count (delay slot) */
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b shifts2 /* 00 10 */
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ldi 16,tmp3 /* load shift count (delay slot) */
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b shifts2 /* 00 11 */
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ldi 24,tmp3 /* load shift count (delay slot) */
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b shifts1_0 /* 01 00 */
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ldi 8,tmp3 /* load shift count (delay slot) */
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b eq_align1 /* 01 01 */
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ldbs,ma 1(s1),s1word
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b shifts2 /* 01 10 */
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ldi 8,tmp3 /* load shift count (delay slot) */
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b shifts2 /* 01 11 */
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ldi 16,tmp3 /* load shift count (delay slot) */
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b shifts1_0 /* 10 00 */
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ldi 16,tmp3 /* load shift count (delay slot) */
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b shifts1 /* 10 01 */
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ldi 8,tmp3 /* load shift count (delay slot) */
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b eq_align2 /* 10 10 */
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ldhs,ma 2(s1),s1word
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b shifts2 /* 10 11 */
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ldi 8,tmp3 /* load shift count (delay slot) */
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b shifts1_0 /* 11 00 */
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ldi 24,tmp3 /* load shift count (delay slot) */
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b shifts1 /* 11 01 */
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ldi 16,tmp3 /* load shift count (delay slot) */
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b shifts1 /* 11 10 */
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ldi 8,tmp3 /* load shift count (delay slot) */
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ldbs,ma 1(s1),s1word /* 11 11 */
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ldbs,ma 1(s2),s2word
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sub,= s1word,s2word,ret0 /* if not equal, we can return now */
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bv,n r0(rp)
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comclr,<> s1word,r0,ret0
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bv,n r0(rp)
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b loop /* fall into main loop */
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ldwm 4(s1),s1word
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eq_align1:
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ldbs,ma 1(s2),s2word
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sub,= s1word,s2word,ret0 /* if not equal, we can return now */
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bv,n r0(rp)
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comclr,<> s1word,r0,ret0
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bv,n r0(rp)
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/* fall through to half-word aligned case */
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ldhs,ma 2(s1),s1word /* load next halfword */
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eq_align2:
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ldhs,ma 2(s2),s2word /* load next halfword */
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/* form the mask: 0xffff0000 and mask leading nulls in s1word and s2word
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so that we can fall into the main loop with word aligned data */
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ldi 16,save
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mtctl save,r11
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zvdepi -2,32,save
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or save,s1word,s1word
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b loop_plus /* fall into main loop */
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or save,s2word,s2word
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/* s2's alignment is greater than s1's alignment, so we will shift s1 */
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shifts1_0:
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addi -4,s1,s1 /* fix up s1 due to earlier read */
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shifts1:
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extru s1,31,2,tmp1
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extru s2,31,2,tmp5
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dep r0,31,2,s1 /* Compute word address of s1 */
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dep r0,31,2,s2 /* Compute word address of s2 */
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ldwm 4(s1),s1word /* get first word of s1 */
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ldwm 4(s2),s2word /* get first word of s2 */
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combt,=,n r0,tmp1,masks2 /* Do we need to mask beginning of s1 */
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sh3add tmp1,r0,save /* save now has number of bits to mask */
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mtctl save,r11
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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:
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sh3add tmp5,r0,save /* save now has number of bits to mask */
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mtctl save,r11
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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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ldi -1,tmp7 /* load tmp7 with 0xffffffff */
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mtctl tmp3,r11 /* Move shift amount to CR11 */
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more: uxor,nbz s1word,r0,r0 /* Is there a null in s1? */
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b ends1
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vshd tmp7,s1word,save
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combf,=,n save,s2word,cmps1
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ldwm 4(s1),tmp7
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ldwm 4(s2),s2word
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uxor,nbz tmp7,r0,r0 /* is there a null in s1? */
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b ends1_0
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vshd s1word,tmp7,save
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combf,=,n save,s2word,cmps1
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ldwm 4(s1),s1word
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b more
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ldwm 4(s2),s2word
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cmps1: movb,tr save,s1word,wordcomparereturn
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nop
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ends1_0:
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copy tmp7,s1word /* move tmp7 to s1word */
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ends1:
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combf,=,n save,s2word,nullins1 /* branch if no match */
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copy save,s1word /* delay slot */
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/* At this point, we know that we've read a null */
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/* from s1, so we can't read more from s1 */
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uxor,nbz save,r0,r0 /* are the strings equal? */
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b,n samestring
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vshd s1word,r0,s1word
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b nullins1
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ldwm 4(s2),s2word
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/* s1's alignment is greater than s2's alignment, so we will shift s2 */
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shifts2:
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extru s1,31,2,tmp1
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extru s2,31,2,tmp5
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dep r0,31,2,s1 /* Compute word address of s1 */
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dep r0,31,2,s2 /* Compute word address of s2 */
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ldwm 4(s2),s2word /* get first word of s2 */
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ldwm 4(s1),s1word /* get first word of s1 */
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combt,=,n r0,tmp5,masks1 /* Do we need to mask beginning of s2 */
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sh3add tmp5,r0,save /* save now has number of bits to mask */
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mtctl save,r11
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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:
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sh3add tmp1,r0,save /* save now has number of bits to mask */
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mtctl save,r11
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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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ldi -1,tmp7 /* load tmp7 with 0xffffffff */
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mtctl tmp3,r11 /* Move shift amount to CR11 */
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more1: uxor,nbz s2word,r0,r0 /* is there a null in s2? */
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b ends2
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vshd tmp7,s2word,save
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combf,=,n s1word,save,cmps2
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ldwm 4(s2),tmp7
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ldwm 4(s1),s1word
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uxor,nbz tmp7,r0,r0 /* is there a null in s2? */
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b ends2_0
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vshd s2word,tmp7,save
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combf,=,n s1word,save,cmps2
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ldwm 4(s2),s2word
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b more1
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ldwm 4(s1),s1word
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cmps2: movb,tr save,s2word,wordcomparereturn
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nop
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ends2_0:
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copy tmp7,s2word /* move tmp7 to s2word */
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ends2:
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combf,=,n s1word,save,nullins1 /* branch if no match */
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copy save,s2word /* delay slot */
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/* At this point, we know that we've read a null */
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/* from s2, so we can't read more from s2 */
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uxor,nbz save,r0,r0 /* are the strings equal? */
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b,n samestring
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vshd s2word,r0,s2word
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b nullins1
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ldwm 4(s1),s1word
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EXIT(strcmp)
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