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 | memset - fill memory with a constant byte |
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33 | Syntax: |
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34 | void *memset(void *s, int c, size_t n); |
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35 | Description: |
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36 | The memset function copies the value of c (converted to an unsigned char) |
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37 | into each of the first n characters of the object pointed to by s. |
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38 | Return value: |
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39 | The memset function returns the value of s. |
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40 | */ |
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41 | .text |
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42 | .align 2 |
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43 | .globl memset |
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44 | .type memset, @function |
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45 | memset: |
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46 | /* Corner case. If n is zero, just go return. */ |
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47 | beqz $r2, .Lend_memset |
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48 | |
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49 | /* Keep $r0 as return value. |
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50 | Set $r4 as how many words to copy. |
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51 | Set $r2 as how many bytes are less than a word. */ |
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52 | move $r5, $r0 |
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53 | srli $r4, $r2, 2 |
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54 | andi $r2, $r2, 3 |
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55 | beqz $r4, .Lbyte_set |
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56 | |
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57 | /* Set $r1 a word-size pattern composed of the value of c |
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58 | (converted to an unsigned char). Convert ??????ab to abababab. */ |
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59 | andi $r1, $r1, 0xff /* Set $r1 = 000000ab. */ |
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60 | slli $r3, $r1, 8 /* Set $r3 = 0000ab00. */ |
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61 | or $r1, $r1, $r3 /* Set $r1 = 0000abab. */ |
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62 | slli $r3, $r1, 16 /* Set $r3 = abab0000. */ |
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63 | or $r1, $r1, $r3 /* Set $r1 = abababab. */ |
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64 | |
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65 | .Lword_set: |
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66 | /* Do the word set $r4 times. Then, do the byte set $r2 times. */ |
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67 | addi $r4, $r4, -1 |
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68 | smw.bim $r1, [$r5], $r1 /* Set a word-size. */ |
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69 | bnez $r4, .Lword_set /* Loop again ? */ |
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70 | beqz $r2, .Lend_memset /* Fall THRU or go return ? */ |
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71 | |
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72 | .Lbyte_set: |
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73 | /* Do the byte set $r2 times. */ |
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74 | addi $r2, $r2, -1 |
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75 | sbi.p $r1, [$r5], 1 /* Set a byte-size. */ |
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76 | bnez $r2, .Lbyte_set /* Loop again ? */ |
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77 | |
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78 | .Lend_memset: |
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79 | ret |
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80 | .size memset, .-memset |
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