C1/73C0: C2 31        REP #$31                  Flags and direct page manipulation.
C1/73C2: 0B           PHD 
C1/73C3: 48           PHA 
C1/73C4: 7B           TDC 
C1/73C5: 69 EC FF     ADC #$FFEC
C1/73C8: 5B           TCD 
C1/73C9: 68           PLA 
C1/73CA: 86 12        STX $12                   $12 = X = arg2
C1/73CC: A9 01 00     LDA #$0001                Argument loop.
C1/73CF: 18           CLC 
C1/73D0: ED CA 97     SBC $97CA
C1/73D3: 50 04        BVC $73D9
C1/73D5: 10 17        BPL $73EE
C1/73D7: 80 02        BRA $73DB
C1/73D9: 30 13        BMI $73EE
C1/73DB: 8A           TXA 
C1/73DC: E2 20        SEP #$20
C1/73DE: AE CA 97     LDX $97CA
C1/73E1: 9D BA 97     STA $97BA,X
C1/73E4: C2 20        REP #$20
C1/73E6: EE CA 97     INC $97CA
C1/73E9: A9 C0 73     LDA #$73C0
C1/73EC: 80 2F        BRA $741D
C1/73EE: 20 42 00     JSR $0042                 Jump to C1/0042 (A is loaded with the value at 7E964D)
C1/73F1: C9 00 00     CMP #$0000                If A = 0, end.
C1/73F4: F0 24        BEQ $741A
C1/73F6: A6 12        LDX $12                   X = arg2 - 1
C1/73F8: CA           DEX 
C1/73F9: AD BA 97     LDA $97BA                 A = arg1 - 1
C1/73FC: 29 FF 00     AND #$00FF
C1/73FF: 3A           DEC 
C1/7400: 22 C9 FA C3  JSR $C3FAC9               A = arg1 - 1, X = arg2 - 1.

C3/FAC9: C2 31        REP #$31                  Flags and direct manipulation.
C3/FACB: 0B           PHD 
C3/FACC: 48           PHA 
C3/FACD: 7B           TDC 
C3/FACE: 69 F0 FF     ADC #$FFF0
C3/FAD1: 5B           TCD 
C3/FAD2: 68           PLA 
C3/FAD3: 9B           TXY                       Y = arg2 - 1.
C3/FAD4: AA           TAX                       X = arg1 - 1.
C3/FAD5: 86 0E        STX $0E                   $0E = arg1 - 1.
C3/FAD7: AE 72 A9     LDX $A972
C3/FADA: BD 0F 00     LDA $000F,X               A = $000F + value at $7EA972
C3/FADD: 29 FF 00     AND #$00FF
C3/FAE0: C9 D5 00     CMP #$00D5                If it's 0xD5, A = 1 and exit. Return value is 1
C3/FAE3: D0 05        BNE $FAEA
C3/FAE5: A9 01 00     LDA #$0001
C3/FAE8: 80 1D        BRA $FB07
C3/FAEA: AE 72 A9     LDX $A972                 If not 0xD5, continue here.
C3/FAED: BD 0E 00     LDA $000E,X               A = $000E + value at $7EA972
C3/FAF0: 29 FF 00     AND #$00FF
C3/FAF3: D0 0B        BNE $FB00
C3/FAF5: A6 0E        LDX $0E                   A = 0 case
C3/FAF7: 8A           TXA                       A = arg1 - 1.
C3/FAF8: 20 81 F9     JSR $F981
C3/FAFB: A9 00 00     LDA #$0000                Return value is 0
C3/FAFE: 80 07        BRA $FB07
C3/FB00: 98           TYA                       A != 0 case
C3/FB01: 20 81 F9     JSR $F981                 A = arg2 - 1
C3/FB04: A9 01 00     LDA #$0001                Return value is 1
C3/FB07: 2B           PLD 
C3/FB08: 6B           RTL 

C1/7404: C9 00 00     CMP #$0000                Value at $000F + value at 7EA972 != D5, and... 
C1/7407: 85 06        STA $06                   value at $000E + value at 7EA972 == 00.
C1/7409: 64 08        STZ $08
C1/740B: 10 02        BPL $740F                 Negative flag set? Then decrement $08 (make it FF).
C1/740D: C6 08        DEC $08
C1/740F: A5 06        LDA $06                   06+08 -> 0E+10
C1/7411: 85 0E        STA $0E
C1/7413: A5 08        LDA $08
C1/7415: 85 10        STA $10
C1/7417: 20 5D 04     JSR $045D
C1/741A: A9 00 00     LDA #$0000
C1/741D: 2B           PLD 
C1/741E: 60           RTS