1 | /* |
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2 | Copyright (c) 2013 Andes Technology Corporation. |
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3 | All rights reserved. |
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4 | |
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5 | Redistribution and use in source and binary forms, with or without |
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6 | modification, are permitted provided that the following conditions are met: |
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7 | |
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8 | Redistributions of source code must retain the above copyright |
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9 | notice, this list of conditions and the following disclaimer. |
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10 | |
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11 | Redistributions in binary form must reproduce the above copyright |
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12 | notice, this list of conditions and the following disclaimer in the |
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13 | documentation and/or other materials provided with the distribution. |
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14 | |
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15 | The name of the company may not be used to endorse or promote |
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16 | products derived from this software without specific prior written |
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17 | permission. |
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18 | |
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19 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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20 | AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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21 | IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
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22 | DISCLAIMED. IN NO EVENT SHALL RED HAT INCORPORATED BE LIABLE FOR ANY |
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23 | DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
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24 | (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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25 | LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
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26 | ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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27 | (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
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28 | SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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29 | |
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30 | |
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31 | Function: |
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32 | strcmp - compare two strings. |
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33 | Syntax: |
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34 | int strcmp(const char *s1, const char *s2); |
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35 | Description: |
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36 | This function compares the two strings s1 and s2. It returns an |
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37 | integer less than, equal to, or greater than zero if s1 is found, |
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38 | respectively, to be less than, to match, or be greater than s2. |
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39 | Return value: |
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40 | strcmp returns an integer less than, equal to, or greater than |
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41 | zero if s1 (or the first n bytes thereof) is found, respectively, |
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42 | to be less than, to match, or be greater than s2. |
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43 | */ |
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44 | .text |
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45 | .align 2 |
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46 | .globl strcmp |
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47 | .type strcmp, @function |
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48 | strcmp: |
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49 | /* If s1 or s2 are unaligned, then compare bytes. */ |
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50 | or $r5, $r1, $r0 |
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51 | andi $r5, $r5, #3 |
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52 | bnez $r5, .Lbyte_mode |
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53 | |
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54 | /* If s1 and s2 are word-aligned, compare them a word at a time. */ |
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55 | lwi $r5, [$r0+(0)] |
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56 | lwi $r3, [$r1+(0)] |
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57 | bne $r5, $r3, .Lbyte_mode /* A difference was detected, so |
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58 | search bytewise. */ |
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59 | |
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60 | /* It's more efficient to set bit mask outside the word_mode loop. */ |
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61 | sethi $r4, hi20(0xFEFEFEFF) /* Set $r4 as -0x01010101. */ |
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62 | ori $r4, $r4, lo12(0xFEFEFEFF) |
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63 | sethi $r2, hi20(0x80808080) |
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64 | ori $r2, $r2, lo12(0x80808080) |
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65 | b .Ldetect_null |
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66 | |
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67 | .align 2 |
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68 | .Lword_mode: |
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69 | lmw.aim $r5, [$r0], $r5 |
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70 | lmw.aim $r3, [$r1], $r3 |
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71 | bne $r5, $r3, .Lbyte_mode |
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72 | |
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73 | .Ldetect_null: |
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74 | /* #define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080) |
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75 | DETECTNULL returns nonzero if (long)X contains a NULL byte. */ |
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76 | nor $r3, $r5, $r5 /* r3 = ~(X) */ |
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77 | add $r5, $r5, $r4 /* r2 = ((X) - 0x01010101) */ |
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78 | and $r5, $r5, $r3 /* r2 = ~(X) & ((X) - 0x01010101) */ |
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79 | and $r5, $r5, $r2 /* r2= r2 & 0x80808080 */ |
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80 | beqz $r5, .Lword_mode /* No NULL byte, compare next word. */ |
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81 | |
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82 | /* To get here, *a1 == *a2, thus if we find a null in *a1, |
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83 | then the strings must be equal, so return zero. */ |
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84 | movi $r0, #0 |
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85 | ret |
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86 | |
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87 | .Lbyte_mode: |
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88 | /* Byte-mode compare. */ |
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89 | lbi.bi $r5, [$r0], #1 |
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90 | lbi.bi $r3, [$r1], #1 |
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91 | bne $r5, $r3, 1f /* Mismatch, done. */ |
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92 | bnez $r5, .Lbyte_mode |
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93 | 1: |
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94 | sub $r0, $r5, $r3 |
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95 | ret |
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96 | .size strcmp, .-strcmp |
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