1 | ; Project name : Print library |
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2 | ; Description : ASM library for character and string |
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3 | ; printing using direct access to VRAM. |
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4 | ; |
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5 | ; NOT WORKING!!! |
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6 | |
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7 | ;--------------- Equates ----------------------------- |
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8 | |
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9 | %include "BDA.inc" ; For BDA variables |
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10 | |
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11 | ; Int 10h (BIOS) functions |
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12 | FN_BIOS_WR_CHAR_TEL EQU 0Eh ; Teletype Output |
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13 | |
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14 | ; Color adapter or Mono adapter segments |
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15 | SEG_COLOR EQU 0B800h ; CGA+ |
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16 | SEG_MONO EQU 0B000h ; MDA, Hercules |
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17 | |
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18 | |
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19 | ;-------------- Public functions --------------------- |
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20 | ; Section containing code |
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21 | SECTION .text |
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22 | |
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23 | ;-------------------------------------------------------------------- |
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24 | ; Return pointer to VRAM for current cursor position. |
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25 | ; |
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26 | ; PrntVram_GetPtr |
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27 | ; Parameters: |
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28 | ; Nothing |
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29 | ; Returns: |
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30 | ; ES:DI: Pointer to cursor location |
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31 | ; Corrupts registers: |
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32 | ; AX |
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33 | ;-------------------------------------------------------------------- |
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34 | ALIGN JUMP_ALIGN |
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35 | PrntVram_GetPtr: |
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36 | push dx |
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37 | xor ax, ax ; Zero AX |
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38 | mov es, ax ; Copy zero to ES (BDA segment) |
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39 | |
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40 | ; Calculate offset to VRAM |
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41 | eMOVZX di, [es:BDA.bVidPageIdx] ; Load page index |
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42 | shl di, 1 ; Shift for word lookup |
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43 | mov ax, [es:di+BDA.rgwVidCurPos] ; Load cursor position |
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44 | shl ax, 1 ; Cursor offsets to WORD offsets |
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45 | eMOVZX di, al ; Copy X offset to DI |
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46 | mov al, ah ; Y offset to AL |
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47 | xor ah, ah ; Y offset to AX |
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48 | mul WORD [es:BDA.wVidColumns] ; DX:AX = Y offset * Column cnt |
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49 | add di, [es:BDA.wVidPageOff] ; Add page offset to DI |
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50 | add di, ax ; Add row offset to DI |
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51 | |
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52 | ; Get segment to VRAM |
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53 | mov ax, SEG_COLOR ; Assume CGA+ |
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54 | cmp BYTE [es:BDA.bVidMode], 7 ; MDA or Hercules? |
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55 | jne .Return ; If not, return |
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56 | mov ax, SEG_MONO |
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57 | ALIGN JUMP_ALIGN |
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58 | .Return: |
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59 | mov es, ax |
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60 | pop dx |
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61 | ret |
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62 | |
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63 | |
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64 | ;-------------------------------------------------------------------- |
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65 | ; Prints character. All character printing functions must |
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66 | ; use this macro to print characters (so printing implementation |
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67 | ; can be easily modified when needed). |
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68 | ; |
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69 | ; PRINT_CHAR |
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70 | ; Parameters: |
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71 | ; DL: Character to print |
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72 | ; Returns: |
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73 | ; Nothing |
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74 | ; Corrupts registers: |
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75 | ; AX |
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76 | ;-------------------------------------------------------------------- |
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77 | %macro PRINT_CHAR 0 |
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78 | call PrntVram_TeleChar |
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79 | %endmacro |
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80 | |
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81 | ALIGN JUMP_ALIGN |
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82 | PrntVram_TeleChar: |
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83 | cmp dl, 20h ; Printable char? |
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84 | jb .Bios ; If not, use BIOS functions |
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85 | push es |
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86 | push di |
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87 | call PrntVram_GetPtr ; VRAM pointer to ES:DI |
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88 | mov [es:di], dl ; Store character |
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89 | call PtnrVram_IncCursor ; Increment cursor position |
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90 | pop di |
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91 | pop es |
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92 | ret |
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93 | ALIGN JUMP_ALIGN |
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94 | .Bios: |
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95 | push bp ; Save because of buggy BIOSes |
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96 | push bx |
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97 | mov ah, FN_BIOS_WR_CHAR_TEL |
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98 | mov al, dl ; Copy char to write |
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99 | xor bx, bx ; Page 0 |
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100 | int 10h |
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101 | pop bx |
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102 | pop bp |
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103 | ret |
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104 | |
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105 | ALIGN JUMP_ALIGN |
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106 | PtnrVram_IncCursor: |
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107 | push es |
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108 | xor ax, ax ; Zero AX |
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109 | mov es, ax ; Copy zero to ES (BDA segment) |
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110 | mov al, [es:BDA.rgwVidCurPos] |
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111 | inc ax |
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112 | cmp al, [es:BDA.wVidColumns] |
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113 | pop es |
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114 | je .IncRow |
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115 | |
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116 | ; Inc column only |
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117 | push dx |
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118 | push cx |
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119 | push bx |
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120 | mov cx, 1 |
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121 | call MenuCrsr_Move |
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122 | pop bx |
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123 | pop cx |
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124 | pop dx |
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125 | ret |
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126 | ALIGN JUMP_ALIGN |
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127 | .IncRow: |
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128 | push dx |
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129 | push cx |
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130 | push bx |
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131 | call MenuCrsr_GetCursor |
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132 | xor dl, dl |
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133 | inc dh |
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134 | call MenuCrsr_SetCursor |
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135 | pop bx |
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136 | pop cx |
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137 | pop dx |
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138 | ret |
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139 | |
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140 | |
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141 | ;-------------------------------------------------------------------- |
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142 | ; Prints string. All string printing functions must |
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143 | ; use this macro to print strings (so printing implementation |
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144 | ; can be easily modified when needed). |
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145 | ; |
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146 | ; PRINT_STR |
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147 | ; Parameters: |
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148 | ; DS:DX: Ptr to STOP terminated string |
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149 | ; Returns: |
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150 | ; Nothing |
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151 | ; Corrupts registers: |
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152 | ; AX |
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153 | ;-------------------------------------------------------------------- |
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154 | %macro PRINT_STR 0 |
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155 | push dx |
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156 | call Print_VramTeleStr |
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157 | pop dx |
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158 | %endmacro |
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159 | |
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160 | |
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161 | ;-------------------------------------------------------------------- |
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162 | ; Prints string and returns number of characters printed. |
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163 | ; All string printing functions must use this macro to print strings |
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164 | ; (so printing implementation can be easily modified when needed). |
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165 | ; |
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166 | ; PRINT_STR_LEN |
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167 | ; Parameters: |
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168 | ; DS:DX: Ptr to STOP terminated string |
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169 | ; Returns: |
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170 | ; DX: Number of characters printed |
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171 | ; Corrupts registers: |
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172 | ; AX |
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173 | ;-------------------------------------------------------------------- |
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174 | %macro PRINT_STR_LEN 0 |
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175 | call Print_VramTeleStr |
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176 | %endmacro |
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177 | |
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178 | ALIGN JUMP_ALIGN |
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179 | Print_VramTeleStr: |
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180 | push es |
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181 | push di |
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182 | push si |
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183 | call PrntVram_GetPtr ; VRAM pointer to ES:DI |
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184 | mov si, dx ; Copy offset to string |
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185 | xor dx, dx ; Zero char counter |
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186 | cld ; STOSB to increment SI and DI |
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187 | ALIGN JUMP_ALIGN |
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188 | .CharLoop: |
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189 | lodsb ; Load char from [DS:SI] to AL |
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190 | cmp al, 20h ; Printable character? |
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191 | jb .Bios ; If not, use BIOS functions |
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192 | |
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193 | push dx |
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194 | mov al, dl |
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195 | PRINT_CHAR |
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196 | pop dx |
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197 | |
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198 | ;stosb ; Store char to [ES:DI] |
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199 | inc dx ; Increment chars printed |
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200 | ;inc di ; Skip attribute |
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201 | jmp .CharLoop ; Loop while chars left |
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202 | ALIGN JUMP_ALIGN |
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203 | .Return: |
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204 | pop si |
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205 | pop di |
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206 | pop es |
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207 | ret |
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208 | ALIGN JUMP_ALIGN |
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209 | .Bios: |
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210 | cmp al, STOP ; End of string? |
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211 | je .Return ; If so, return |
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212 | push dx |
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213 | mov dl, al |
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214 | PRINT_CHAR |
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215 | pop dx |
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216 | times 2 inc di |
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217 | inc dx ; Increment chars printed |
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218 | jmp .CharLoop ; Loop while chars left |
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