| [41] | 1 | ; Project name : Assembly Library |
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| 2 | ; Description : Functions for managing display page. |
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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 | ; DisplayPage_SetFromAL |
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| 9 | ; Parameters: |
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| 10 | ; AL: New display page |
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| 11 | ; DS: BDA segment (zero) |
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| 12 | ; Returns: |
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| 13 | ; Nothing |
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| 14 | ; Corrupts registers: |
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| 15 | ; AX, DX |
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| 16 | ;-------------------------------------------------------------------- |
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| 17 | ALIGN JUMP_ALIGN |
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| 18 | DisplayPage_SetFromAL: |
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| 19 | xor ah, ah |
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| 20 | mul WORD [VIDEO_BDA.wBytesPerPage] ; AX = Offset to page |
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| 21 | mov [VIDEO_BDA.displayContext+DISPLAY_CONTEXT.fpCursorPosition], ax |
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| 22 | ret |
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| 23 | |
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| 24 | |
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| 25 | ;-------------------------------------------------------------------- |
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| 26 | ; DisplayPage_GetColumnsToALandRowsToAH |
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| 27 | ; Parameters: |
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| 28 | ; DS: BDA segment (zero) |
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| 29 | ; Returns: |
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| 30 | ; AL: Number of columns in selected text mode |
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| 31 | ; AH: Number of rows in selected text mode |
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| 32 | ; Corrupts registers: |
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| 33 | ; Nothing |
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| 34 | ;-------------------------------------------------------------------- |
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| 35 | ALIGN JUMP_ALIGN |
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| 36 | DisplayPage_GetColumnsToALandRowsToAH: |
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| 37 | mov al, [VIDEO_BDA.wColumns] ; 40 or 80 |
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| 38 | mov ah, 25 ; Always 25 rows on standard text modes |
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| 39 | ret |
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| 40 | |
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| 41 | |
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| 42 | ;-------------------------------------------------------------------- |
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| 43 | ; DisplayPage_SynchronizeToHardware |
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| 44 | ; Parameters: |
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| 45 | ; DS: BDA segment (zero) |
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| 46 | ; Returns: |
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| 47 | ; Nothing |
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| 48 | ; Corrupts registers: |
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| 49 | ; AX, DX |
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| 50 | ;-------------------------------------------------------------------- |
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| 51 | ALIGN JUMP_ALIGN |
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| 52 | DisplayPage_SynchronizeToHardware: |
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| 53 | xor dx, dx |
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| 54 | mov ax, [VIDEO_BDA.displayContext+DISPLAY_CONTEXT.fpCursorPosition] |
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| 55 | div WORD [VIDEO_BDA.wBytesPerPage] ; AX = Page |
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| 56 | |
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| 57 | cmp al, [VIDEO_BDA.bActivePage] |
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| 58 | je SHORT .Return ; Same page, no need to synchronize |
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| 59 | mov ah, SELECT_ACTIVE_DISPLAY_PAGE |
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| 60 | int BIOS_VIDEO_INTERRUPT_10h |
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| 61 | .Return: |
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| 62 | ret |
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