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Routines |
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Used by the routine at routine29.
enter with coordinates in BC
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| test_pixel | B755 | LD ($5C7D),BC | store BC in COORDS system variable (x-coordinate of last point plotted) | |
| B759 | CALL $22AA | call PIXEL-ADD in Spectrum ROM (get pixel address in HL) | ||
| B75C | LD B,A | set loop counter by loading position of pixel within byte into B and adding one | ||
| B75D | INC B | |||
| B75E | LD A,(HL) | load byte in screen bitmap from address in HL | ||
| test_pixel_0 | B75F | RLCA | rotate A left 'B' times | |
| B760 | DJNZ test_pixel_0 | |||
| B762 | AND $01 | return if LSB is zero | ||
| B764 | RET Z | |||
| B765 | LD (LOF_D),A | else store $01 in LOF_D and return | ||
| B768 | RET | |||
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