1 | ; Project name : Assembly Library
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2 | ; Description : Functions for processing characters in a string.
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3 |
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4 | ; Section containing code
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5 | SECTION .text
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6 |
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7 | ;--------------------------------------------------------------------
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8 | ; Character processing callback function prototype for StringProcess_DSSIwithFunctionInDX.
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9 | ; Parameters:
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10 | ; AL: Character to process
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11 | ; CX: Character number (index for next character)
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12 | ; DS:SI: Ptr to next character
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13 | ; BX,DI,ES: Free to use by processing function
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14 | ; Returns:
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15 | ; CF: Clear to continue with next character
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16 | ; Set to stop processing
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17 | ; BX,DI,ES: Free to use by processing function
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18 | ; Corrupts registers:
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19 | ; AX
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20 | ;--------------------------------------------------------------------
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21 |
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22 |
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23 | ;--------------------------------------------------------------------
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24 | ; StringProcess_DSSIwithFunctionInDX
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25 | ; Parameters:
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26 | ; DX: Character processing function
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27 | ; DS:SI: Ptr to NULL terminated string to convert
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28 | ; Returns:
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29 | ; CX: Number of characters processed
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30 | ; CF: Clear if all characters processed
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31 | ; Set if terminated by processing function
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32 | ; Corrupts registers:
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33 | ; Nothing (processing function can corrupt BX,DI,ES)
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34 | ;--------------------------------------------------------------------
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35 | ALIGN STRING_JUMP_ALIGN
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36 | StringProcess_DSSIwithFunctionInDX:
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37 | push si
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38 | push ax
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39 |
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40 | xor cx, cx
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41 | ALIGN STRING_JUMP_ALIGN
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42 | .ProcessNextCharacter:
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43 | lodsb
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44 | test al, al ; NULL to end string
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45 | jz SHORT .EndOfString ; Return with CF cleared
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46 | inc cx
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47 | call dx
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48 | jnc SHORT .ProcessNextCharacter
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49 |
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50 | ALIGN STRING_JUMP_ALIGN
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51 | .EndOfString:
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52 | pop ax
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53 | pop si
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54 | ret
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55 |
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56 |
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57 | ;--------------------------------------------------------------------
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58 | ; StringProcess_ConvertToLowerCase (callback function for StringProcess_DSSIwithFunctionInDX)
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59 | ; Parameters:
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60 | ; AL: Character to convert to lower case
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61 | ; DS:SI: Ptr to next character
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62 | ; Returns:
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63 | ; CF: Clear to continue processing
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64 | ; Corrupts registers:
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65 | ; AL
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66 | ;--------------------------------------------------------------------
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67 | ALIGN STRING_JUMP_ALIGN
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68 | StringProcess_ConvertToLowerCase:
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69 | call Char_ALtoLowerCaseLetter
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70 | mov [si-1], al
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71 | clc
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72 | ret
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73 |
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74 |
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75 | ;--------------------------------------------------------------------
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76 | ; StringProcess_ConvertToWordInDIWithBaseInBX (callback function for StringProcess_DSSIwithFunctionInDX)
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77 | ; Parameters:
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78 | ; AL: Character to convert to lower case
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79 | ; BX: Numeric base (2, 10 or 16)
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80 | ; Returns:
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81 | ; CF: Clear to continue processing
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82 | ; Set if error
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83 | ; Corrupts registers:
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84 | ; AX
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85 | ;--------------------------------------------------------------------
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86 | ALIGN STRING_JUMP_ALIGN
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87 | StringProcess_ConvertToWordInDIWithBaseInBX:
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88 | call Char_ConvertIntegerToALfromDigitInALwithBaseInBX
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89 | cmc
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90 | jc SHORT .InvalidCharacter
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91 | push dx
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92 |
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93 | xor ah, ah ; Digit converted to integer now in AX
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94 | xchg ax, di
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95 | mul bx ; Old WORD *= base
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96 | jc SHORT .Overflow
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97 | add di, ax ; Add old WORD to new integer
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98 |
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99 | .Overflow:
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100 | pop dx
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101 | .InvalidCharacter:
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102 | ret
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