| ← B2C9 | Map | B306 → |
B2CB: Draw the "LEVEL nnn" status caption
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Draws the LEVEL caption once per level. It counts the digit cells up, so the caption shows the displayed level.
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| draw_level_number | B2CB | LD A,$30 | Reset the tens digit of the level caption to ASCII '0'. The hundreds cell beside it keeps the value the previous laps left there. The new-game setup clears all three at the start of a game. |
| B2CD | LD (level_caption_tens),A | ||
| B2D0 | LD A,$B1 | Seed the units digit to game-font '1'; the count starts at 1, so the caption shows the level index plus one within the current lap. The game font's digits carry bit 7, so this last digit also terminates the print string. | |
| B2D2 | LD (level_caption_units),A | ||
| B2D5 | LD A,(level) | On the first level of a lap the seeded "01" prints after the hundreds digit, which stays as it is. | |
| B2D8 | OR A | ||
| B2D9 | JR Z,draw_level_number_1 | ||
| B2DB | LD B,A | Otherwise step the counter up by the level index. | |
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Each pass adds one to the displayed level and carries into the tens and the hundreds. The displayed level is the level index plus one, plus a hundred for each completed lap of the level tables. The index wraps to 0 at the end of a lap while the hundreds digit stands, so the caption counts on past 100. The carry into the hundreds lands on the pass that takes the count from 99 to 100. The lap digit therefore advances while the last level of a lap is drawn.
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| draw_level_number_0 | B2DC | LD HL,level_caption_units | Step the units digit; it wraps at the game font's ':' back to '0' and carries left. |
| B2DF | INC (HL) | ||
| B2E0 | LD A,(HL) | ||
| B2E1 | CP $BA | ||
| B2E3 | JR NZ,level_caption_next | ||
| B2E5 | LD (HL),$B0 | Wrapped units carry into the tens, which wrap at ASCII ':' the same way. | |
| B2E7 | DEC HL | ||
| B2E8 | INC (HL) | ||
| B2E9 | LD A,(HL) | ||
| B2EA | CP $3A | ||
| B2EC | JR NZ,level_caption_next | ||
| B2EE | LD (HL),$30 | That carry reaches the hundreds, the lap digit. | |
| B2F0 | DEC HL | ||
| B2F1 | INC (HL) | ||
| B2F2 | LD A,(HL) | ||
| B2F3 | CP $3A | ||
| B2F5 | JR NZ,level_caption_next | ||
| B2F7 | LD (HL),$30 | The hundreds wrap too, so the caption counts modulo 1000. | |
| level_caption_next | B2F9 | DJNZ draw_level_number_0 | One pass per level of the index |
| draw_level_number_1 | B2FB | LD HL,SCREEN_BASE+$A | Print the caption double-height at character row 0, column 10. |
| B2FE | LD DE,level_caption_text | ||
| B301 | LD C,$47 | ||
| B303 | JP print_string_2x | ||
| ← B2C9 | Map | B306 → |