Pokémon mini Development Documentation

CP = Compare (16-bits)

Hex	Mnemonic	Cycles
D4 nn mm	CP BA,#mmnn	3
D5 nn mm	CP HL,#mmnn	3
D6 nn mm	CP IX,#mmnn	3
D7 nn mm	CP IY,#mmnn	3
CF 6C nn mm	CP SP,#mmnn	4
CF 18	CP BA,BA	4
CF 19	CP BA,HL	4
CF 1A	CP BA,IX	4
CF 1B	CP BA,IY	4
CF 38	CP HL,BA	4
CF 39	CP HL,HL	4
CF 3A	CP HL,IX	4
CF 3B	CP HL,IY	4
CF 5C	CP SP,BA	4
CF 5D	CP SP,HL	4

Execute

hhll = Immediate unsigned 16-bits
BA   = Register BA: (B shl 8) or A
HL   = Register HL: (H shl 8) or L
IX   = Register IX
IY   = Register IY
SP   = Register SP (Stack Pointer)

; CP Sc2, Sc
;
; Sc2 = Source 2
; Sc  = Source

(discarded) = Sc2 - Sc

Description

Subtracts “16-bits Source 2” with “16-bits Source”, result is discarded.

This instruction is used to compare values.

Conditions

• Zero: Set when result is 0
• Carry: Set when result is < 0
• Overflow: Set when result overflow 16-bits signed range (< -32768 OR > 32767)
• Negative: Set when bit 15 of the result is 1

Examples

; BA = 0x2EF0
CP BA, $1337
; BA = 0x2EF0
;      0x1BB9 (0x2EF0 - 0x1337 = 0x(0)1BB9)
; SC = (Zero=0):(Carry=0):(Overflow=0):(Negative=0)

; HL = 0xBB7E
; BA = 0xCF12
CP BA, HL
; HL = 0xBB7E
; BA = 0xCF12
;     0xEC6C (0xCF12 - 0xBB7E = 0x(1)EC6C)
; SC = (Zero=0):(Carry=1):(Overflow=0):(Negative=1)

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