| 1 | ; Project name : Assembly Library |
|---|
| 2 | ; Description : Functions for managing display page. |
|---|
| 3 | |
|---|
| 4 | ; Section containing code |
|---|
| 5 | SECTION .text |
|---|
| 6 | |
|---|
| 7 | ;-------------------------------------------------------------------- |
|---|
| 8 | ; DisplayPage_SetFromAL |
|---|
| 9 | ; Parameters: |
|---|
| 10 | ; AL: New display page |
|---|
| 11 | ; DS: BDA segment (zero) |
|---|
| 12 | ; Returns: |
|---|
| 13 | ; Nothing |
|---|
| 14 | ; Corrupts registers: |
|---|
| 15 | ; AX, DX |
|---|
| 16 | ;-------------------------------------------------------------------- |
|---|
| 17 | ALIGN JUMP_ALIGN |
|---|
| 18 | DisplayPage_SetFromAL: |
|---|
| 19 | xor ah, ah |
|---|
| 20 | mul WORD [VIDEO_BDA.wBytesPerPage] ; AX = Offset to page |
|---|
| 21 | mov [VIDEO_BDA.displayContext+DISPLAY_CONTEXT.fpCursorPosition], ax |
|---|
| 22 | ret |
|---|
| 23 | |
|---|
| 24 | |
|---|
| 25 | ;-------------------------------------------------------------------- |
|---|
| 26 | ; DisplayPage_GetColumnsToALandRowsToAH |
|---|
| 27 | ; Parameters: |
|---|
| 28 | ; DS: BDA segment (zero) |
|---|
| 29 | ; Returns: |
|---|
| 30 | ; AL: Number of columns in selected text mode |
|---|
| 31 | ; AH: Number of rows in selected text mode |
|---|
| 32 | ; Corrupts registers: |
|---|
| 33 | ; Nothing |
|---|
| 34 | ;-------------------------------------------------------------------- |
|---|
| 35 | ALIGN JUMP_ALIGN |
|---|
| 36 | DisplayPage_GetColumnsToALandRowsToAH: |
|---|
| 37 | mov al, [VIDEO_BDA.wColumns] ; 40 or 80 |
|---|
| 38 | mov ah, 25 ; Always 25 rows on standard text modes |
|---|
| 39 | ret |
|---|
| 40 | |
|---|
| 41 | |
|---|
| 42 | ;-------------------------------------------------------------------- |
|---|
| 43 | ; DisplayPage_SynchronizeToHardware |
|---|
| 44 | ; Parameters: |
|---|
| 45 | ; DS: BDA segment (zero) |
|---|
| 46 | ; Returns: |
|---|
| 47 | ; Nothing |
|---|
| 48 | ; Corrupts registers: |
|---|
| 49 | ; AX, DX |
|---|
| 50 | ;-------------------------------------------------------------------- |
|---|
| 51 | ALIGN JUMP_ALIGN |
|---|
| 52 | DisplayPage_SynchronizeToHardware: |
|---|
| 53 | xor dx, dx |
|---|
| 54 | mov ax, [VIDEO_BDA.displayContext+DISPLAY_CONTEXT.fpCursorPosition] |
|---|
| 55 | div WORD [VIDEO_BDA.wBytesPerPage] ; AX = Page |
|---|
| 56 | |
|---|
| 57 | cmp al, [VIDEO_BDA.bActivePage] |
|---|
| 58 | je SHORT .Return ; Same page, no need to synchronize |
|---|
| 59 | mov ah, SELECT_ACTIVE_DISPLAY_PAGE |
|---|
| 60 | int BIOS_VIDEO_INTERRUPT_10h |
|---|
| 61 | .Return: |
|---|
| 62 | ret |
|---|
