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Routines |
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30042 | XOR A | Clear the buffer ready for writing | |||||||||
30043 | LD B,64 | ||||||||||
30045 | LD (DE),A | ||||||||||
30046 | INC DE | ||||||||||
30047 | DJNZ 30045 | ||||||||||
30049 | DEC DE | Point DE at the last byte of the buffer | |||||||||
30050 | LD C,62 | There are 62 pixel columns available for writing in | |||||||||
30052 | LD A,(HL) | Pick up a character from the message in A | |||||||||
30053 | INC HL | Move to the next character in the message | |||||||||
30054 | AND A | Have we reached the end of the message? | |||||||||
30055 | JR Z,30079 | Jump if so | |||||||||
30057 | PUSH HL | Save the message pointer | |||||||||
30058 | LD L,A | Point HL at the pixel width of the bitmap for the character in A | |||||||||
30059 | LD H,217 | ||||||||||
30061 | LD A,(HL) | Pick up the width in A | |||||||||
30062 | LD B,A | Transfer the width to B | |||||||||
30063 | INC H | Point HL at the next font character bitmap byte | |||||||||
30064 | LD A,(HL) | Pick this up in A | |||||||||
30065 | CALL 30097 | Insert the font character bitmap byte into the buffer | |||||||||
30068 | DEC C | Decrease the pixel column count | |||||||||
30069 | DJNZ 30063 | Jump back until all pixel columns for this letter are done | |||||||||
30071 | XOR A | A=0 (empty vertical pixel column, i.e. space) | |||||||||
30072 | DEC C | Decrease the pixel column count | |||||||||
30073 | CALL 30097 | Insert the space into the buffer | |||||||||
30076 | POP HL | Restore the message pointer to HL | |||||||||
30077 | JR 30052 | Jump back to write the next letter from the message | |||||||||
We've finished writing the message. Now centre it.
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30079 | BIT 7,C | Did we use more than 62 pixel columns? | |||||||||
30081 | RET NZ | Return if so | |||||||||
30082 | RR C | C holds the number of unused pixel columns; halve this and add one to get the padding | |||||||||
30084 | INC C | ||||||||||
30085 | XOR A | Insert an empty pixel column (space) | |||||||||
30086 | CALL 30097 | ||||||||||
30089 | DEC C | Next column of padding | |||||||||
30090 | JR NZ,30085 | Jump back until the text has been centred | |||||||||
30092 | RET |
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