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Routines |
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Used by the routine at Draw_Room_Rows_Loop.
Prints the heads-up display header showing Energy, Lives and Score, then applies random colours to the bottom two rows of the screen attributes to create a colourful ground strip.
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| Print_HUD_Header | 63BB | LD A,$01 | Write 01 to *Screen_Initialised_Flag. | |
| 63BD | LD ($5FA1),A | |||
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Print the HUD string to the upper screen.
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| 63C0 | CALL $1601 | Call CHAN_OPEN to open channel 02 (upper screen). | ||
| 63C3 | LD HL,$63E9 | Point HL at Messaging_Header. | ||
| 63C6 | LD B,$4F | Set a counter in B for the length of the string (4F characters). | ||
| 63C8 | CALL PrintString | Call PrintString. | ||
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This entry point is used by the routine at Draw_Room_Rows_Loop.
Apply pseudo-random colours to the bottom two rows of screen attributes to create a colourful ground strip. Uses the Memory Refresh Register as a seed to pick unpredictable colour values.
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| Colour_Ground_Strip | 63CB | LD A,R | Load the Memory Refresh Register into E as a pointer offset. | |
| 63CD | LD E,A | |||
| 63CE | LD D,$00 | Set D to 00 so DE is an offset into low memory. | ||
| 63D0 | LD B,$20 | Set a counter in B for 20 attribute cells. | ||
| 63D2 | LD HL,$5AC0 | Point HL at 5AC0 (start of the bottom two attribute rows). | ||
| Colour_Ground_Loop | 63D5 | LD A,(DE) | Fetch a pseudo-random byte from *DE. | |
| 63D6 | AND %00000111 | Keep only bits 0-2 (INK colour). | ||
| 63D8 | INC DE | Advance the source pointer. | ||
| 63D9 | CP $03 | Jump back to Colour_Ground_Loop if the colour is less than 03 (reject dark colours to keep the ground strip bright). | ||
| 63DB | JR C,Colour_Ground_Loop | |||
| 63DD | PUSH DE | Stash the source pointer on the stack. | ||
| 63DE | LD E,A | Copy the chosen colour into E. | ||
| 63DF | LD A,(HL) | Fetch the current attribute byte from *HL. | ||
| 63E0 | AND %11110111 | Mask off the existing INK bits (keep PAPER, BRIGHT, FLASH). | ||
| 63E2 | OR E | OR in the new INK colour from E. | ||
| 63E3 | LD (HL),E | Write the updated attribute byte to *HL. | ||
| 63E4 | POP DE | Restore the source pointer from the stack. | ||
| 63E5 | INC HL | Advance to the next attribute cell. | ||
| 63E6 | DJNZ Colour_Ground_Loop | Decrease the counter and loop back to Colour_Ground_Loop until all 20 cells are coloured. | ||
| 63E8 | RET | Return. | ||
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