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Routines |
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Used by the routine at Burst_Into_Dust.
Makes a burst of noise by sending the bits of the first 30 bytes of the ROM to the speaker. Bit 4 of the port is the speaker bit. The byte is rotated right before each of the eight writes, so every bit of it is sent to the speaker in turn.
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| SoundsDoor | A131 | LD BC,$0830 | BC=0830 (B counts the bits of a byte and C counts 30 bytes). | |
| A134 | LD HL,$0000 | Point at the start of the ROM (00). | ||
| SoundsDoor_Byte | A137 | LD E,(HL) | Fetch a byte of the ROM. | |
| A138 | INC HL | Move on to the next byte. | ||
| A139 | PUSH BC | Stash the counters on the stack. | ||
| SoundsDoor_Bit | A13A | RRC E | Rotate the byte right. | |
| A13C | LD A,E | Copy it to A. | ||
| A13D | AND %00010000 | Keep only the speaker bit. | ||
| A13F | OUT ($FE),A | Send it to the speaker. | ||
| A141 | DJNZ SoundsDoor_Bit | Decrease the bit counter and loop back until all eight bits are sent. | ||
| A143 | POP BC | Restore the counters from the stack. | ||
| A144 | DEC C | Decrease the byte counter and loop back until all of the bytes have been sent. | ||
| A145 | JR NZ,SoundsDoor_Byte | |||
| A147 | RET | Return. | ||
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View the equivalent code in;
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