Routines
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66CE: Get the next character of a message being spoken or written
Used by the routines at 6791, 6A08 and 6B1B. Returns with the next character in A.
Input
H Number of the character speaking or writing (0xB7-0xD1)
66CE LD L,$10 Bytes 0x0F and 0x10 hold the address of the next character in the sub-submessage being written/spoken (if any)
66D0 LD A,(HL)
66D1 AND A Are we working on a sub-submessage?
66D2 JR NZ,$66DC Jump if so
66D4 LD L,$0E Bytes 0x0D and 0x0E hold the address of the next character in the submessage being written/spoken (if any)
66D6 LD A,(HL)
66D7 AND A Are we working on a submessage?
66D8 JR NZ,$66DC Jump if so
66DA LD L,$0C We're working on a top-level message
66DC LD D,(HL) DE=address of the next character in the (sub)(sub)message
66DD DEC L
66DE LD E,(HL)
66DF LD A,(DE) Pick up the character code in A
66E0 INC DE Move the pointer to the next character and store the address for future reference
66E1 LD (HL),E
66E2 INC L
66E3 LD (HL),D
66E4 AND A Has the end of the (sub)(sub)message been reached?
66E5 JR NZ,$66F0 Jump if not
We've reached the end of the (sub)(sub)message.
66E7 LD (HL),$00 Signal: end of (sub)(sub)message
66E9 DEC L L=0x0B (top-level message), 0x0D (submessage) or 0x0F (sub-submessage)
66EA BIT 2,L Has the end of the top-level message been reached (L=0x0B)?
66EC RET Z Return if so
66ED DEC L Otherwise go up to the submessage or the top-level message and jump back to deal with it
66EE JR $66DC
We haven't reached the end of the (sub)(sub)message yet. Determine whether the next code is a regular character code or a pointer to another message.
66F0 SUB $20
66F2 CP $60
66F4 JR NC,$66F9 Jump with character codes 0x01-0x1F or 0x80 onwards
66F6 ADD A,$20
66F8 RET Return with the standard ASCII code in A
66F9 ADD A,$20
66FB CP $03
66FD RET C Return with character codes 0x01 and 0x02 (end of line)
The next character in the message is actually a pointer to another message. Find the address of that message, and store it for future reference.
66FE LD E,A DE points to the LSB of the start address of the (sub)submessage
66FF LD D,$FE
6701 INC L L=0x0D (submessage) or 0x0F (sub-submessage)
6702 LD A,(DE) A=LSB of the start address of the (sub)submessage
6703 LD (HL),A Store it in byte 0x0D or 0x0F of the character's buffer
6704 INC L L=0x0E (submessage) or 0x10 (sub-submessage)
6705 INC D A=MSB of the address of the (sub)submessage
6706 LD A,(DE)
6707 LD (HL),A Store it in byte 0x0E or 0x10 of the character's buffer
6708 JR $66DC Jump back to collect a character from this (sub)submessage
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