|
Routines |
| Prev: C37D | Up: Map | Next: C3E4 |
|
Used by the routines at PrintDateBar, PrintScreenCharacter, RecordResultStorageDecorative, HandleBackspaceKey, PrintARowOfSpaces, ProcessScreenCharacter and UpdateScreenDisplay.
Looks the character up in the font and draws it at the screen address.
|
||||||||||
| PrintCharacter | C388 | PUSH AF | Store that in the low byte and clear the high byte. | |||||||
| C389 | PUSH BC | |||||||||
| C38A | PUSH DE | |||||||||
| C38B | PUSH HL | |||||||||
| C38C | LD L,A | |||||||||
| C38D | LD H,$00 | |||||||||
| C38F | ADD HL,HL | Multiply by 08 (each font character is 08 bytes of data). | ||||||||
| C390 | ADD HL,HL | |||||||||
| C391 | ADD HL,HL | |||||||||
| C392 | LD DE,$3C00 | Point DE at CHARSET minus 0100 plus this character's offset. | ||||||||
| C395 | ADD HL,DE | |||||||||
| C396 | EX DE,HL | |||||||||
| C397 | POP HL | Restore the screen address from the stack. | ||||||||
| C398 | PUSH HL | Keep a copy of it. | ||||||||
| C399 | LD B,$08 | Set a counter in B for 08 bytes of the font data. | ||||||||
| PrintCharacter_0 | C39B | LD A,(DE) | Read the next byte of this character's bitmap and keep the counters. | |||||||
| C39C | PUSH BC | |||||||||
| C39D | PUSH AF | |||||||||
|
Does this character need shifting?
|
||||||||||
| C39E | DEC C | See whether this character needs shifting. | ||||||||
| C39F | INC C | |||||||||
| C3A0 | LD B,$FF | Go to PrintCharacter_Next if the count reaches zero. | ||||||||
| C3A2 | JR Z,PrintCharacter_Next | |||||||||
| PrintCharacter_Loop | C3A4 | SRL A | Jump back to PrintCharacter_Loop while the count is not finished. | |||||||
| C3A6 | SRL B | |||||||||
| C3A8 | DEC C | |||||||||
| C3A9 | JR NZ,PrintCharacter_Loop | |||||||||
| PrintCharacter_Next | C3AB | LD C,A | Take the count. | |||||||
| C3AC | LD A,B | |||||||||
| C3AD | CPL | Invert the shifted mask so it covers the screen pixels to keep. | ||||||||
| C3AE | AND (HL) | Keep the screen pixels outside the character. | ||||||||
| C3AF | OR C | Add the pixels of the character. | ||||||||
| C3B0 | LD (HL),A | Store it at the pointer. | ||||||||
| C3B1 | POP AF | |||||||||
| C3B2 | POP BC | |||||||||
|
Is the character byte-aligned?
|
||||||||||
| C3B3 | DEC C | See whether the shift count is zero without changing it, so the character is byte-aligned. | ||||||||
| C3B4 | INC C | |||||||||
| C3B5 | JR Z,PrintCharacter_NextBitmapByte | Go to PrintCharacter_NextBitmapByte when the shift count is zero, so the character is byte-aligned. | ||||||||
| C3B7 | PUSH BC | Work out how many bit positions are left in this row. | ||||||||
| C3B8 | PUSH AF | |||||||||
| C3B9 | LD A,$08 | |||||||||
| C3BB | SUB C | |||||||||
| C3BC | LD C,A | |||||||||
| C3BD | POP AF | |||||||||
| C3BE | LD B,$FF | Start a mask of all ones, shifted with the character data. | ||||||||
| PrintCharacter_CountFinished | C3C0 | SLA A | Jump back to PrintCharacter_CountFinished while the count is not finished. | |||||||
| C3C2 | SLA B | |||||||||
| C3C4 | DEC C | |||||||||
| C3C5 | JR NZ,PrintCharacter_CountFinished | |||||||||
| C3C7 | LD C,A | Take the count. | ||||||||
| C3C8 | LD A,B | |||||||||
| C3C9 | CPL | Invert the shifted mask so it covers the screen pixels to keep in the next cell. | ||||||||
| C3CA | INC HL | Step to the next character. | ||||||||
| C3CB | AND (HL) | Keep the screen pixels in that cell outside the character. | ||||||||
| C3CC | OR C | Add the part of the character that spills into that cell. | ||||||||
| C3CD | LD (HL),A | Store it at the pointer and step back one character. | ||||||||
| C3CE | DEC HL | |||||||||
| C3CF | POP BC | |||||||||
| PrintCharacter_NextBitmapByte | C3D0 | INC DE | Step to the next bitmap byte and the next pixel row. | |||||||
| C3D1 | INC H | |||||||||
| C3D2 | DJNZ PrintCharacter_0 | Draw the next pixel row and repeat from PrintCharacter_0 until the character is finished. | ||||||||
| C3D4 | POP HL | Add 07 to the total. | ||||||||
| C3D5 | POP DE | |||||||||
| C3D6 | POP BC | |||||||||
| C3D7 | LD A,C | |||||||||
| C3D8 | ADD A,$07 | |||||||||
| C3DA | CP $08 | Jump ahead to PrintCharacter_1 if the total is below 08. | ||||||||
| C3DC | JR C,PrintCharacter_1 | |||||||||
| C3DE | SUB $08 | Drop 08 from the count. | ||||||||
| C3E0 | INC L | |||||||||
| PrintCharacter_1 | C3E1 | LD C,A | Store the result in the low byte of the count. | |||||||
| C3E2 | POP AF | Restore AF from the stack. | ||||||||
| C3E3 | RET | Return. | ||||||||
|
View the equivalent code in;
|
||||||||||
| Prev: C37D | Up: Map | Next: C3E4 |