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 "memccpy.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 1989,1993 Intel Corp., all rights reserved |
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40 | */ |
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41 | /* |
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42 | procedure memccpy (optimized assembler version for the 80960K series) |
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43 | |
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44 | dest_addr = memccpy (dest_addr, src_addr, char, len) |
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45 | |
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46 | copy len bytes pointed to by src_addr to the space pointed to by |
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47 | dest_addr, stopping if char is copied. If char is copied, |
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48 | return address of byte after char in dest string; else null. |
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49 | |
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50 | |
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51 | Undefined behavior will occur if the end of the source array is in |
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52 | the last two words of the program's allocated memory space. This |
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53 | is so because the routine fetches ahead. Disallowing the fetch |
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54 | ahead would impose a severe performance penalty. |
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55 | |
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56 | Undefined behavior will also occur if the source and destination |
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57 | strings overlap. |
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58 | |
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59 | Strategy: |
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60 | |
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61 | Fetch the source array by words and store them by words to the |
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62 | destination array, until there are fewer than three bytes left |
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63 | to copy. Then, using the last word of the source (the one that |
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64 | contains the remaining 0, 1, 2, or 3 bytes to be copied), store |
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65 | a byte at a time until Ldone. |
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66 | |
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67 | Tactics: |
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68 | |
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69 | 1) Do NOT try to fetch and store the words in a word aligned manner |
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70 | because, in my judgement, the performance degradation experienced due |
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71 | to non-aligned accesses does NOT outweigh the time and complexity added |
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72 | by the preamble and convoluted body that would be necessary to assure |
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73 | alignment. This is supported by the intuition that most source and |
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74 | destination arrays (even more true of most big source arrays) will |
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75 | be word aligned to begin with. |
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76 | |
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77 | 2) Rather than decrementing len to zero, |
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78 | I calculate the address of the byte after the last byte of the |
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79 | destination array, and quit when the destination byte pointer passes |
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80 | that. |
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81 | |
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82 | */ |
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83 | |
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84 | .globl _memccpy |
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85 | .leafproc _memccpy, __memccpy |
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86 | .align 2 |
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87 | _memccpy: |
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88 | #ifndef __PIC |
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89 | lda Lrett,g14 |
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90 | #else |
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91 | lda Lrett-(.+8)(ip),g14 |
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92 | #endif |
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93 | __memccpy: |
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94 | mov g14, g13 # preserve return address |
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95 | cmpibge 0,g3,Lexit_char_not_found |
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96 | |
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97 | addo g3,g1,g3 # compute beyond end of src |
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98 | ld (g1), g7 # fetch first word of source |
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99 | lda 0xff,g5 # mask for char |
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100 | and g5,g2,g2 # extract only char |
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101 | shlo 8,g2,g6 |
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102 | or g2,g6,g6 |
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103 | shlo 16,g6,g4 |
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104 | or g6,g4,g6 # word of char |
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105 | b Lwloop_b |
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106 | |
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107 | Lwloop_a: |
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108 | ld (g1), g7 # fetch ahead next word of source |
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109 | st g4, (g0) # store word to dest |
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110 | addo 4, g0, g0 # post-increment dest pointer |
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111 | Lwloop_b: # word copying loop |
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112 | addo 4, g1, g1 # pre-increment src pointer |
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113 | cmpo g3, g1 # is len <= 3 ? |
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114 | mov g7, g4 # keep a copy of the current word |
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115 | bl Lcloop_setup # quit word loop if less than 4 bytes |
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116 | scanbyte g6, g7 # check for char |
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117 | bno Lwloop_a # continue word loop if char not found. |
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118 | |
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119 | Lcloop_setup: |
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120 | subo 4, g1, g1 # back down src pointer |
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121 | cmpobe g1, g3, Lexit_char_not_found |
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122 | |
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123 | Lcloop_a: # character copying loop (len < 3) |
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124 | and g5,g4,g7 # check the byte against char |
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125 | cmpo g7,g2 |
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126 | stob g7,(g0) # store the byte |
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127 | addo 1, g0, g0 |
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128 | be Lexit_char_found |
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129 | addo 1,g1,g1 |
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130 | cmpo g1,g3 |
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131 | shro 8,g4,g4 # position next byte |
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132 | bne Lcloop_a |
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133 | |
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134 | Lexit_char_not_found: |
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135 | mov 0, g0 |
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136 | Lexit_char_found: |
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137 | lda 0,g14 |
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138 | bx (g13) # g0 = dest array address; g14 = 0 |
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139 | Lrett: |
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140 | ret |
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141 | |
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142 | |
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143 | /* end of memccpy */ |
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