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Routines |
| Prev: 29142 | Up: Map | Next: 29272 |
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| 29174 | PUSH HL | Store HL (pointer to entry in lookup table for RLE terrain interaction data) | ||||||
| 29175 | LD HL,23495 | Modify instruction at 29220 to load x-coordinate of graphic's right edge into A... | ||||||
| 29178 | LD (29221),HL | ...i.e. set end x-coordinate for painting left-to-right | ||||||
| 29181 | LD HL,29241 | Modify instruction at 29224 to jump to 29241... | ||||||
| 29184 | LD (29225),HL | ...i.e. advance HL down one character row in terrain interaction data table at 24064 | ||||||
| 29187 | LD A,35 | Modify instruction at 29227 with opcode 35 (INC HL)... | ||||||
| 29189 | LD (29227),A | ... | ||||||
| 29192 | POP HL | Restore HL (pointer to entry in lookup table for RLE terrain interaction data) | ||||||
| 29193 | CALL 29036 | Store coordinates of area to be coloured and point IX at RLE terrain interaction data | ||||||
| 29196 | LD BC,(23493) | 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 29082, 29110 and 29142.
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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| 29200 | PUSH BC | Store BC (B = current y-coordinate, C = initial x-coordinate) | ||||||
| 29201 | CALL 54162 | Point HL at terrain interaction data table address for character coordinates x=C, y=B | ||||||
| 29204 | LD A,(IX+0) | Load A with repeat count value | ||||||
| 29207 | OR A | If repeat count is zero... | ||||||
| 29208 | JP Z,29237 | ...then jump to 29237 | ||||||
| 29211 | LD B,A | Load B with repeat count | ||||||
| 29212 | LD C,(IX+1) | Load C with terrain interaction parameter to paint | ||||||
| 29215 | LD (HL),C | Apply terrain interaction parameter in C to current terrain interaction data table location in HL | ||||||
| 29216 | LD A,L | Load E with x-coordinate (characters) of current terrain interaction data location... | ||||||
| 29217 | AND 31 | ... | ||||||
| 29219 | LD E,A | ... | ||||||
| 29220 | LD A,(23495) | Load A with end x-coordinate for painting... | ||||||
| 29223 | CP E | ...and if this is the same as the x-coordinate... | ||||||
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The operand of the instruction at 29224 (i.e. the destination of the jump) is modified by the instructions at 29092, 29120, 29152 and 29184 to be 29262 (move up one character row), 29262 (move up one character row), 29241 (move down one character row) or 29241 (move down one character row) respectively.
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| 29224 | JP Z,29241 | ...then jump to routine to move up or down one character row | ||||||
| 29227 | INC HL | Advance HL to next (or previous) byte in terrain interaction data table | ||||||
| 29228 | DJNZ 29215 | Decrease B (repeat count) and loop back to 29215 if not zero | ||||||
| 29230 | INC IX | Advance IX by two bytes in RLE terrain interaction data... | ||||||
| 29232 | INC IX | ... | ||||||
| 29234 | JP 29204 | Loop back to 29204 for this new data | ||||||
| 29237 | POP BC | Restore BC (B = current y-coordinate, C = initial x-coordinate) | ||||||
| 29238 | JP 28095 | Advance IX to start of next room layout data entry and jump back to 27989 to paint its attributes / terrain interaction data | ||||||
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Move down one character row
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| 29241 | EXX | Switch registers | ||||||
| 29242 | LD A,(23496) | Load A with one more than y-coordinate of bottom edge of area to paint... | ||||||
| 29245 | INC A | ... | ||||||
| 29246 | POP BC | Restore BC (B = current y-coordinate, C = initial x-coordinate) | ||||||
| 29247 | INC B | Increase B (i.e. move down a character row) | ||||||
| 29248 | PUSH BC | Store BC (B = updated y-coordinate, C = initial x-coordinate) | ||||||
| 29249 | CP B | If B is the same as A (i.e. we are now outside the area to be painted)... | ||||||
| 29250 | JP Z,29237 | ...then jump to 29237 | ||||||
| 29253 | CALL 54162 | Load HL with terrain interaction data table address for coordinates (C, B) and load E with x-coordinate (characters) | ||||||
| 29256 | PUSH HL | Store HL (new terrain interaction data table address) | ||||||
| 29257 | EXX | Switch registers | ||||||
| 29258 | POP HL | Restore HL (new terrain interaction data table address) | ||||||
| 29259 | JP 29228 | Jump back to 29228 and continue painting | ||||||
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Move up one character row
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| 29262 | EXX | Switch registers | ||||||
| 29263 | LD A,(23494) | Load A with one less than y-coordinate of top edge of area to paint... | ||||||
| 29266 | DEC A | ... | ||||||
| 29267 | POP BC | Restore BC (B = current y-coordinate, C = initial x-coordinate) | ||||||
| 29268 | DEC B | Increase B (i.e. move down a character row) | ||||||
| 29269 | JP 29248 | Jump back to 29248 | ||||||
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