[2] | 1 | ; Project name : Print library |
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[293] | 2 | ; Description : ASM library for character and string |
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[2] | 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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[293] | 25 | ; |
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[2] | 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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[293] | 41 | eMOVZX di, [es:BDA.bVidPageIdx] ; Load page index |
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[2] | 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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[293] | 68 | ; |
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[2] | 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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[293] | 115 | |
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[2] | 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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[293] | 145 | ; |
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[2] | 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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[293] | 165 | ; |
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[2] | 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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[293] | 192 | |
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[2] | 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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[293] | 197 | |
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[2] | 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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