Combat
Table of contents
Initialize
Print **** COMBAT ****
6FB0 20 21 08 JSR $0821 ; PRINT
6FB3 8D 8D ^M^M
6FB5 AA AA AA AA A0 C3 CF CD C2 C1 D4 A0 AA AA AA AA **** COMBAT ****
6FC5 8D 8D 00 ^M^M^@
Store the value of $C0 in $E6 (we’ll come back later to work out what these are)
6FC8 A5 C0 LDA $C0
6FCA 85 E6 STA $E6
Zero out the $EFXX page (the onscreen map?)
6FCC A2 00 LDX #$00
6FCE 8A TXA
6FCF 9D 00 EF STA $EF00,X
6FD2 CA DEX
6FD3 D0 FA BNE $6FCF
Work Out Which Combat Map to Load
if $0E >= 0x14 and $C8 is NOT a ship (0x10 - 0x13), go to $7004
otherwise continue
6FD5 A5 0E LDA $0E
6FD7 C9 14 CMP #$14
6FD9 90 0A BCC $6FE5
6FDB A5 C8 LDA $C8
6FDD C9 14 CMP #$14
6FDF B0 23 BCS $7004
6FE1 C9 10 CMP #$10
6FE3 90 1F BCC $7004
So, $0E is less than 0x14 OR $C8 is a ship.
If $C0 == 0x80, set $E6 to be 0xC8 and load combat map CONT (two ships)
otherwise continue
6FE5 A5 C0 LDA $C0
6FE7 C9 80 CMP #$80
6FE9 D0 09 BNE $6FF4
6FEB A9 C8 LDA #$C8
6FED 85 E6 STA $E6
6FEF A9 D4 LDA #$D4 ; 'T'
6FF1 4C 6D 70 JMP $706D
($0E is less than 0x14 OR $C8 is a ship) ($C0 is NOT 0x80)
If $C3 is less than 0x03 (i.e. it’s water), load combat map CONP (ship at sea)
otherwise load combat map CONE (ship with land to north).
6FF4 A5 C3 LDA $C3
6FF6 C9 03 CMP #$03
6FF8 90 05 BCC $6FFF
6FFA A9 C5 LDA #$C5 ; 'E'
6FFC 4C 6D 70 JMP $706D
6FFF A9 D0 LDA #$D0 ; 'P'
7001 4C 6D 70 JMP $706D
We get to $7004 if $0E >= 0x14 and $C8 is NOT a ship (0x10 - 0x13).
If $C0 is 0x80, set $E6 to 0xC8 and load combat map CONI (ship with land to south) otherwise (if $C0 is NOT 0x80) if $C3 is less than 0x03 (i.e. it’s water), load combat map CONO (coastal) otherwise ($C3 is NOT water) go to next section and choose map based on $C8.
7004 A5 C0 LDA $C0
7006 C9 80 CMP #$80
7008 D0 09 BNE $7013
700A A9 C8 LDA #$C8
700C 85 E6 STA $E6
700E A9 C9 LDA #$C9 ; 'I'
7010 4C 6D 70 JMP $706D
7013 A5 C3 LDA $C3
7015 C9 03 CMP #$03
7017 B0 05 BCS $701E
7019 A9 CF LDA #$CF ; 'O'
701B 4C 6D 70 JMP $706D
To summarize the above
| $0E < 0x14 OR $C8 is a ship | $C0 == 0x80 | $C3 < 0x03 | CON_ | map |
|---|---|---|---|---|
| y | y | T | two ships | |
| y | n | y | P | ship at sea |
| y | n | n | E | ship with land to north |
| n | y | I | ship with land to south | |
| n | n | y | O | coastal |
| n | n | n | see next table |
Choose map based on value in $C8
| $C8 | tile | CON_ | map |
|---|---|---|---|
| 0x03 | swamp | S | swamp |
| 0x05 | light forest | B | grass 1 |
| 0x06 | heavy forest | F | forest |
| 0x07 | hills | H | hills |
| 0x16 | cobblestone | D | cobblestone |
| 0x3E | brick paving | C | brick |
| 0x17 | bridge 1 | R | bridge |
| 0x19 | bridge 2 | R | bridge |
| 0x1A | bridge 3 | R | bridge |
| 0x3F | bridge 4 | R | bridge |
| otherwise | G | grass 2 |
701E A5 C8 LDA $C8
7020 C9 03 CMP #$03 ; if == 0x03
7022 D0 05 BNE $7029
7024 A9 D3 LDA #$D3 ; 'S'
7026 4C 6D 70 JMP $706D
7029 C9 05 CMP #$05 ; if == 0x05
702B D0 05 BNE $7032
702D A9 C2 LDA #$C2 ; 'B'
702F 4C 6D 70 JMP $706D
7032 C9 06 CMP #$06 ; if == 0x06
7034 D0 05 BNE $703B
7036 A9 C6 LDA #$C6 ; 'F'
7038 4C 6D 70 JMP $706D
703B C9 07 CMP #$07 ; if == 0x07
703D D0 05 BNE $7044
703F A9 C8 LDA #$C8 ; 'H'
7041 4C 6D 70 JMP $706D
7044 C9 16 CMP #$16 ; if == 0x16
7046 D0 05 BNE $704D
7048 A9 C4 LDA #$C4 ; 'D'
704A 4C 6D 70 JMP $706D
704D C9 3E CMP #$3E ; if == 0x3E
704F D0 05 BNE $7056 ;
7051 A9 C3 LDA #$C3 ; 'C'
7053 4C 6D 70 JMP $706D
7056 C9 17 CMP #$17 ; if == 0x17
7058 F0 0C BEQ $7066
705A C9 19 CMP #$19 ; if == 0x19
705C F0 08 BEQ $7066
705E C9 1A CMP #$1A ; if == 0x1A
7060 F0 04 BEQ $7066
7062 C9 3F CMP #$3F ; if == 0x3F
7064 D0 05 BNE $706B
7066 A9 D2 LDA #$D2 ; 'R'
7068 4C 6D 70 JMP $706D
706B A9 C7 LDA #$C7 ; otherwise 'G'