1 | /******************************************************************************* |
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2 | * |
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3 | * Copyright (c) 1993 Intel Corporation |
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4 | * |
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5 | * Intel hereby grants you permission to copy, modify, and distribute this |
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6 | * software and its documentation. Intel grants this permission provided |
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7 | * that the above copyright notice appears in all copies and that both the |
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8 | * copyright notice and this permission notice appear in supporting |
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9 | * documentation. In addition, Intel grants this permission provided that |
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10 | * you prominently mark as "not part of the original" any modifications |
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11 | * made to this software or documentation, and that the name of Intel |
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12 | * Corporation not be used in advertising or publicity pertaining to |
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13 | * distribution of the software or the documentation without specific, |
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14 | * written prior permission. |
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15 | * |
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16 | * Intel Corporation provides this AS IS, WITHOUT ANY WARRANTY, EXPRESS OR |
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17 | * IMPLIED, INCLUDING, WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY |
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18 | * OR FITNESS FOR A PARTICULAR PURPOSE. Intel makes no guarantee or |
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19 | * representations regarding the use of, or the results of the use of, |
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20 | * the software and documentation in terms of correctness, accuracy, |
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21 | * reliability, currentness, or otherwise; and you rely on the software, |
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22 | * documentation and results solely at your own risk. |
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23 | * |
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24 | * IN NO EVENT SHALL INTEL BE LIABLE FOR ANY LOSS OF USE, LOSS OF BUSINESS, |
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25 | * LOSS OF PROFITS, INDIRECT, INCIDENTAL, SPECIAL OR CONSEQUENTIAL DAMAGES |
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26 | * OF ANY KIND. IN NO EVENT SHALL INTEL'S TOTAL LIABILITY EXCEED THE SUM |
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27 | * PAID TO INTEL FOR THE PRODUCT LICENSED HEREUNDER. |
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28 | * |
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29 | ******************************************************************************/ |
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30 | |
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31 | .file "strcmp.s" |
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32 | #ifdef __PIC |
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33 | .pic |
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34 | #endif |
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35 | #ifdef __PID |
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36 | .pid |
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37 | #endif |
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38 | /* |
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39 | * (c) copyright 1988,1993 Intel Corp., all rights reserved |
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40 | */ |
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41 | /* |
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42 | procedure strcmp (optimized assembler version for the 80960K Series) |
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43 | |
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44 | result = strcmp (src1_addr, src2_addr) |
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45 | |
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46 | compare the null terminated string pointed to by src1_addr to |
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47 | the string pointed to by src2_addr. Return 0 iff the strings |
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48 | are equal, -1 if src1_addr is lexicographically less than src2_addr, |
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49 | and 1 if it is lexicographically greater. |
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50 | |
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51 | Undefined behavior will occur if the end of either source string |
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52 | (i.e. the terminating null byte) is in the last two words of the |
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53 | program's allocated memory space. This is so because strcmp fetches |
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54 | ahead. Disallowing the fetch ahead would impose a severe performance |
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55 | penalty. |
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56 | |
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57 | Strategy: |
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58 | |
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59 | Fetch the source strings by words and compare the words until either |
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60 | differing words are found or the null byte is encountered. In either |
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61 | case, move through the word until either the differing byte if found, |
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62 | in which case return -1 or 1 appropriately; or the null byte is |
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63 | encountered, in which case, return zero (equality). |
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64 | |
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65 | Tactics: |
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66 | |
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67 | 1) Do NOT try to fetch the words in a word aligned manner because, |
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68 | in my judgement, the performance degradation experienced due to |
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69 | non-aligned accesses does NOT outweigh the time and complexity added |
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70 | by the preamble and convoluted body that would be necessary to assure |
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71 | alignment. This is supported by the intuition that many source |
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72 | strings will be word aligned to begin with. |
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73 | */ |
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74 | |
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75 | .globl _strcmp |
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76 | .globl __strcmp |
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77 | .leafproc _strcmp,__strcmp |
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78 | .align 2 |
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79 | |
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80 | _strcmp: |
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81 | #ifndef __PIC |
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82 | lda .Lrett,g14 |
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83 | #else |
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84 | lda .Lrett-(.+8)(ip),g14 |
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85 | #endif |
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86 | __strcmp: |
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87 | ld (g0), g5 # fetch first word of source_1 |
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88 | mov g14,g7 # preserve return address |
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89 | ldconst 0,g14 # conform to register conventions |
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90 | ldconst 0xff,g4 # byte extraction mask |
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91 | .Lwloop: |
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92 | addo 4,g0,g0 # post-increment source_1 byte ptr |
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93 | ld (g1), g3 # fetch word of source_2 |
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94 | scanbyte 0,g5 # does word have a null byte? |
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95 | mov g5,g2 # save a copy of the source_1 word |
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96 | be .Lcloop # branch if null byte encountered |
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97 | cmpo g2,g3 # are the source words the same? |
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98 | addo 4,g1,g1 # post-increment source_2 byte ptr |
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99 | ld (g0), g5 # fetch ahead next word of source_1 |
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100 | be .Lwloop # fall thru if words are unequal |
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101 | |
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102 | .Lcloop: and g4,g2,g5 # extract and compare individual bytes |
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103 | and g4,g3,g6 |
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104 | cmpobne g5,g6,.diff # if they differ, go return 1 or -1 |
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105 | cmpo 0,g6 # they are the same. Are they null? |
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106 | shlo 8,g4,g4 # position mask for next extraction |
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107 | bne .Lcloop # loop if null not encountered |
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108 | |
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109 | mov 0,g0 # return equality |
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110 | bx (g7) |
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111 | .Lrett: |
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112 | ret |
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113 | .diff: bl .neg |
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114 | mov 1,g0 |
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115 | bx (g7) |
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116 | .neg: subi 1,0,g0 |
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117 | .Lexit: |
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118 | bx (g7) |
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