[41] | 1 | ; File name : Line Splitter.asm |
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| 2 | ; Project name : Assembly Library |
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| 3 | ; Created date : 8.8.2010 |
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| 4 | ; Last update : 15.9.2010 |
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| 5 | ; Author : Tomi Tilli |
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| 6 | ; Description : Splits long strings to multiple lines. |
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| 7 | |
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| 8 | struc LINE_SPLITTER |
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| 9 | .pLastWord resb 2 |
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| 10 | .wMaxLineLength resb 2 |
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| 11 | .wLines resb 2 |
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| 12 | endstruc |
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| 13 | |
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| 14 | |
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| 15 | ; Section containing code |
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| 16 | SECTION .text |
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| 17 | |
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| 18 | ;-------------------------------------------------------------------- |
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| 19 | ; LineSplitter_SplitStringFromDSSIwithMaxLineLengthInAXandGetLineCountToAX |
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| 20 | ; Parameters: |
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| 21 | ; AX: Maximum allowed length for a line |
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| 22 | ; DS:SI: Ptr to string to split |
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| 23 | ; Returns: |
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| 24 | ; AX: Number of lines |
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| 25 | ; Corrupts registers: |
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| 26 | ; CX, SI |
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| 27 | ;-------------------------------------------------------------------- |
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| 28 | ALIGN JUMP_ALIGN |
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| 29 | LineSplitter_SplitStringFromDSSIwithMaxLineLengthInAXandGetLineCountToAX: |
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| 30 | xor cx, cx |
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| 31 | cmp [si], cl ; String length zero? |
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| 32 | jne SHORT .PrepareToSplit |
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| 33 | xchg ax, cx |
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| 34 | ret |
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| 35 | |
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| 36 | ALIGN JUMP_ALIGN |
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| 37 | .PrepareToSplit: |
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| 38 | eENTER_STRUCT LINE_SPLITTER_size ; SS:BP now points to LINE_SPLITTER |
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| 39 | |
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| 40 | mov [bp+LINE_SPLITTER.wLines], cx |
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| 41 | call Memory_SetZFifNullPointerInDSSI |
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| 42 | jz SHORT .ReturnNumberOfLinesInAX |
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| 43 | call SplitStringFromDSSIusingLineSplitterInSSBP |
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| 44 | |
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| 45 | .ReturnNumberOfLinesInAX: |
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| 46 | mov ax, [bp+LINE_SPLITTER.wLines] |
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| 47 | eLEAVE_STRUCT LINE_SPLITTER_size |
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| 48 | ret |
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| 49 | |
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| 50 | ;-------------------------------------------------------------------- |
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| 51 | ; SplitStringFromDSSIusingLineSplitterInSSBP |
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| 52 | ; Parameters: |
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| 53 | ; AX: Maximum allowed length for a line |
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| 54 | ; DS:SI: Ptr to string to split |
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| 55 | ; SS:BP: Ptr to LINE_SPLITTER |
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| 56 | ; Returns: |
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| 57 | ; SS:BP: Ptr to LINE_SPLITTER with number of lines |
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| 58 | ; Corrupts registers: |
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| 59 | ; AX, CX, SI |
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| 60 | ;-------------------------------------------------------------------- |
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| 61 | ALIGN JUMP_ALIGN |
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| 62 | SplitStringFromDSSIusingLineSplitterInSSBP: |
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| 63 | mov [bp+LINE_SPLITTER.pLastWord], si |
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| 64 | mov [bp+LINE_SPLITTER.wMaxLineLength], ax |
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| 65 | inc WORD [bp+LINE_SPLITTER.wLines] ; Always at least one line |
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| 66 | xor cx, cx ; Length of current line |
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| 67 | cld |
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| 68 | ALIGN JUMP_ALIGN |
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| 69 | .ScanNextCharacter: |
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| 70 | lodsb ; Load from [DS:SI] to AL, increment SI |
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| 71 | cmp al, ' ' ; Control character or space? |
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| 72 | je SHORT .ProcessSpace |
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| 73 | jb SHORT .ProcessControlCharacter |
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| 74 | .IncrementCharacterCount: |
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| 75 | inc cx ; Increment character count |
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| 76 | cmp cx, [bp+LINE_SPLITTER.wMaxLineLength] |
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| 77 | jbe SHORT .ScanNextCharacter |
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| 78 | |
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| 79 | mov si, [bp+LINE_SPLITTER.pLastWord] ; Resume to beginning of last word |
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| 80 | mov BYTE [si-1], STX ; STX marks start or new line |
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| 81 | ; Fall to .StartNewLine |
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| 82 | |
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| 83 | ;-------------------------------------------------------------------- |
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| 84 | ; .StartNewLine |
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| 85 | ; Parameters: |
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| 86 | ; CX: Line length so far |
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| 87 | ; DS:SI: Ptr character that begins new line |
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| 88 | ; SS:BP: Ptr to LINE_SPLITTER |
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| 89 | ; Returns: |
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| 90 | ; CX: Zero |
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| 91 | ; SS:BP: LINE_SPLITTER updated for number of lines |
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| 92 | ; Jumps to .ScanNextCharacter |
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| 93 | ; Corrupts registers: |
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| 94 | ; Nothing |
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| 95 | ;-------------------------------------------------------------------- |
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| 96 | .StartNewLine: |
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| 97 | inc WORD [bp+LINE_SPLITTER.wLines] ; Increment number of lines |
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| 98 | xor cx, cx ; Zero line length |
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| 99 | jmp SHORT .ScanNextCharacter |
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| 100 | |
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| 101 | ;-------------------------------------------------------------------- |
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| 102 | ; .ProcessSpace |
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| 103 | ; Parameters: |
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| 104 | ; CX: Line length so far |
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| 105 | ; DS:SI: Ptr first character after space |
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| 106 | ; SS:BP: Ptr to LINE_SPLITTER |
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| 107 | ; Returns: |
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| 108 | ; SS:BP: LINE_SPLITTER updated to beginning of next word |
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| 109 | ; Jumps to .IncrementCharacterCount |
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| 110 | ; Corrupts registers: |
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| 111 | ; Nothing |
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| 112 | ;-------------------------------------------------------------------- |
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| 113 | ALIGN JUMP_ALIGN |
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| 114 | .ProcessSpace: |
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| 115 | mov [bp+LINE_SPLITTER.pLastWord], si |
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| 116 | jmp SHORT .IncrementCharacterCount |
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| 117 | |
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| 118 | ;-------------------------------------------------------------------- |
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| 119 | ; .ProcessControlCharacter |
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| 120 | ; Parameters: |
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| 121 | ; AL: Control character |
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| 122 | ; CX: Line length so far |
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| 123 | ; DS:SI: Ptr inside string to split |
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| 124 | ; SS:BP: Ptr to LINE_SPLITTER |
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| 125 | ; Returns: |
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| 126 | ; SS:BP: LINE_SPLITTER updated to beginning of next line (LF control character) |
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| 127 | ; Corrupts registers: |
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| 128 | ; Nothing |
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| 129 | ;-------------------------------------------------------------------- |
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| 130 | ALIGN JUMP_ALIGN |
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| 131 | .ProcessControlCharacter: |
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| 132 | cmp al, NULL ; End of string? |
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| 133 | je SHORT .EndOfString |
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| 134 | cmp al, LF ; Line feed? |
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| 135 | je SHORT .NewlineCharacter |
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| 136 | cmp al, SOH ; Previous newline character? |
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| 137 | je SHORT .NewlineCharacter |
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| 138 | |
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| 139 | mov BYTE [si-1], ' ' ; Replace unhandled control characters with space |
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| 140 | jmp SHORT .ProcessSpace |
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| 141 | |
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| 142 | ALIGN JUMP_ALIGN |
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| 143 | .NewlineCharacter: |
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| 144 | mov BYTE [si-1], SOH ; SOH marks previous newline character |
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| 145 | mov [bp+LINE_SPLITTER.pLastWord], si |
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| 146 | jmp SHORT .StartNewLine |
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| 147 | |
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| 148 | ALIGN JUMP_ALIGN |
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| 149 | .EndOfString: |
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| 150 | ret |
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| 151 | |
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| 152 | |
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| 153 | ;-------------------------------------------------------------------- |
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| 154 | ; LineSplitter_PrintLineInCXfromStringInESDI |
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| 155 | ; Parameters: |
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| 156 | ; CX: Index of line to print |
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| 157 | ; ES:DI: Ptr to string containing the line |
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| 158 | ; Returns: |
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| 159 | ; Nothing |
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| 160 | ; Corrupts registers: |
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| 161 | ; AX, BX, SI |
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| 162 | ;-------------------------------------------------------------------- |
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| 163 | ALIGN JUMP_ALIGN |
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| 164 | LineSplitter_PrintLineInCXfromStringInESDI: |
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| 165 | push di |
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| 166 | push cx |
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| 167 | |
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| 168 | call LineSplitter_GetOffsetToSIforLineCXfromStringInESDI |
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| 169 | jnc SHORT .LineNotFound |
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| 170 | mov bx, es |
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| 171 | CALL_DISPLAY_LIBRARY PrintCharBufferFromBXSIwithLengthInCX |
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| 172 | .LineNotFound: |
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| 173 | pop cx |
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| 174 | pop di |
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| 175 | ret |
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| 176 | |
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| 177 | |
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| 178 | ;-------------------------------------------------------------------- |
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| 179 | ; LineSplitter_GetOffsetToSIforLineCXfromStringInESDI |
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| 180 | ; Parameters: |
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| 181 | ; CX: Index of line to search for |
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| 182 | ; ES:DI: Ptr to string |
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| 183 | ; Returns: |
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| 184 | ; CX: Line length |
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| 185 | ; ES:SI: Ptr to beginning of line |
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| 186 | ; CF: Set if wanted line was found |
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| 187 | ; Corrupts registers: |
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| 188 | ; AX, DI |
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| 189 | ;-------------------------------------------------------------------- |
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| 190 | ALIGN JUMP_ALIGN |
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| 191 | LineSplitter_GetOffsetToSIforLineCXfromStringInESDI: |
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| 192 | mov si, di ; SI points to start of first line |
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| 193 | mov al, STX ; Last control character to scan for |
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| 194 | inc cx ; Increment CX to get length for first line |
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| 195 | cld |
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| 196 | ALIGN JUMP_ALIGN |
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| 197 | .LineScanLoop: |
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| 198 | scasb ; cmp al, [es:di]. Increment DI |
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| 199 | jb SHORT .LineScanLoop ; Non control character |
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| 200 | |
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| 201 | ; Our end of line characters or NULL character |
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| 202 | dec cx ; Decrement lines to scan through |
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| 203 | jz SHORT .WantedLineFound |
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| 204 | cmp BYTE [es:di-1], NULL |
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| 205 | je SHORT .EndOfString ; Jump with CF cleared |
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| 206 | mov si, di ; SI points to start of new line |
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| 207 | jmp SHORT .LineScanLoop |
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| 208 | |
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| 209 | ALIGN JUMP_ALIGN |
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| 210 | .WantedLineFound: |
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| 211 | stc ; Set CF since wanted line was found |
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| 212 | .EndOfString: |
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| 213 | lahf ; Load FLAGS low to AH |
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| 214 | lea cx, [di-1] ; We don't want control character to be printed |
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| 215 | sub cx, si ; String length to CX |
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| 216 | sahf ; Store AH to FLAGS low |
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| 217 | ret |
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