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Routines |
| Prev: 41141 | Up: Map | Next: 41271 |
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| 41173 | PUSH HL | Store HL (pointer to entry in lookup table for RLE terrain interaction data) | ||||||
| 41174 | LD HL,23410 | Modify instruction at 41219 to load x-coordinate of graphic's right edge into A... | ||||||
| 41177 | LD (41220),HL | ...i.e. set end x-coordinate for painting left-to-right | ||||||
| 41180 | LD HL,41240 | Modify instruction at 41223 to jump to 41240... | ||||||
| 41183 | LD (41224),HL | ...i.e. advance HL down one character row in terrain interaction data table at 23808 | ||||||
| 41186 | LD A,35 | Modify instruction at 41226 with opcode 35 (INC HL)... | ||||||
| 41188 | LD (41226),A | ... | ||||||
| 41191 | POP HL | Restore HL (pointer to entry in lookup table for RLE terrain interaction data) | ||||||
| 41192 | CALL 41035 | Store coordinates of area to be coloured and point IX at RLE terrain interaction data | ||||||
| 41195 | LD BC,(23408) | Load BC with x- and y-coordinates (top-left) defined in current room layout data entry | ||||||
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This entry point is used by the routines at 41081, 41109 and 41141.
At this point, BC holds the initial coordinates in characters, from which to start painting terrain interaction parameters. IX points to the required RLE terrain interaction data.
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| 41199 | PUSH BC | Store BC (B = current y-coordinate, C = initial x-coordinate) | ||||||
| 41200 | CALL 63233 | Point HL at terrain interaction data table address for character coordinates x=C, y=B | ||||||
| 41203 | LD A,(IX+0) | Load A with repeat count value | ||||||
| 41206 | OR A | If repeat count is zero... | ||||||
| 41207 | JP Z,41236 | ...then jump to 41236 | ||||||
| 41210 | LD B,A | Load B with repeat count | ||||||
| 41211 | LD C,(IX+1) | Load C with terrain interaction parameter to paint | ||||||
| 41214 | LD (HL),C | Apply terrain interaction parameter in C to current terrain interaction data table location in HL | ||||||
| 41215 | LD A,L | Load E with x-coordinate (characters) of current terrain interaction data location... | ||||||
| 41216 | AND 31 | ... | ||||||
| 41218 | LD E,A | ... | ||||||
| 41219 | LD A,(23410) | Load A with end x-coordinate for painting... | ||||||
| 41222 | CP E | ...and if this is the same as the x-coordinate... | ||||||
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The operand of the instruction at 41223 (i.e. the destination of the jump) is modified by the instructions at 41091, 41119, 41151 and 41183 to be 41261 (move up one character row), 41261 (move up one character row), 41240 (move down one character row) or 41240 (move down one character row) respectively.
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| 41223 | JP Z,41240 | ...then jump to routine to move up or down one character row | ||||||
| 41226 | INC HL | Advance HL to next (or previous) byte in terrain interaction data table | ||||||
| 41227 | DJNZ 41214 | Decrease B (repeat count) and loop back to 41214 if not zero | ||||||
| 41229 | INC IX | Advance IX by two bytes in RLE terrain interaction data... | ||||||
| 41231 | INC IX | ... | ||||||
| 41233 | JP 41203 | Loop back to 41203 for this new data | ||||||
| 41236 | POP BC | Restore BC (B = current y-coordinate, C = initial x-coordinate) | ||||||
| 41237 | JP 39183 | Advance IX to start of next room layout data entry and jump back to 39067 to paint its attributes / terrain interaction data | ||||||
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Move down one character row
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| 41240 | EXX | Switch registers | ||||||
| 41241 | LD A,(23411) | Load A with one more than y-coordinate of bottom edge of area to paint... | ||||||
| 41244 | INC A | ... | ||||||
| 41245 | POP BC | Restore BC (B = current y-coordinate, C = initial x-coordinate) | ||||||
| 41246 | INC B | Increase B (i.e. move down a character row) | ||||||
| 41247 | PUSH BC | Store BC (B = updated y-coordinate, C = initial x-coordinate) | ||||||
| 41248 | CP B | If B is the same as A (i.e. we are now outside the area to be painted)... | ||||||
| 41249 | JP Z,41236 | ...then jump to 41236 | ||||||
| 41252 | CALL 63233 | Load HL with terrain interaction data table address for coordinates (C, B) and load E with x-coordinate (characters) | ||||||
| 41255 | PUSH HL | Store HL (new terrain interaction data table address) | ||||||
| 41256 | EXX | Switch registers | ||||||
| 41257 | POP HL | Restore HL (new terrain interaction data table address) | ||||||
| 41258 | JP 41227 | Jump back to 41227 and continue painting | ||||||
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Move up one character row
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| 41261 | EXX | Switch registers | ||||||
| 41262 | LD A,(23409) | Load A with one less than y-coordinate of top edge of area to paint... | ||||||
| 41265 | DEC A | ... | ||||||
| 41266 | POP BC | Restore BC (B = current y-coordinate, C = initial x-coordinate) | ||||||
| 41267 | DEC B | Increase B (i.e. move down a character row) | ||||||
| 41268 | JP 41247 | Jump back to 41247 | ||||||
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