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Routines |
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Used by the routine at 30675. Returns with the zero flag set if Sam has dialled a valid telephone number, and with the telephone identifier in A.
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| 31255 | LD HL,27466 | Point HL at the end of the phone number and location table at 27392 | ||
| 31258 | LD C,15 | There are 15 entries to check | ||
| 31260 | LD DE,32661 | Point DE at the last digit of the phone number dialled by Sam (stored at 32658) | ||
| 31263 | LD B,4 | There are 4 digits in a phone number | ||
| 31265 | LD A,(DE) | A=digit of the phone number dialled by Sam | ||
| 31266 | CP (HL) | Compare it with that of a phone number in the table | ||
| 31267 | DEC HL | Point HL at the previous digit of the phone number | ||
| 31268 | DEC DE | Point DE at the previous digit dialled by Sam | ||
| 31269 | JR NZ,31276 | Jump if there's no match | ||
| 31271 | DJNZ 31265 | Jump back until all 4 digits have been compared | ||
| 31273 | LD A,(HL) | A=identifier of the matching telephone | ||
| 31274 | RET | Return with the zero flag set | ||
| 31275 | DEC HL | Point HL at the first byte of the phone number entry (the telephone identifier) | ||
| 31276 | DJNZ 31275 | |||
| 31278 | DEC HL | Point HL at the last digit of the previous phone number in the table | ||
| 31279 | DEC C | Are there any more phone numbers to check? | ||
| 31280 | JR NZ,31260 | Jump back if so | ||
| 31282 | AND A | Reset the zero flag | ||
| 31283 | RET | |||
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