ref: 828edb7403c05eb4837b36e256584dec400af55e
dir: /src/gbz80.7/
.\" .\" This file is part of RGBDS. .\" .\" Copyright (c) 2017-2018, Antonio Nino Diaz and RGBDS contributors. .\" .\" SPDX-License-Identifier: MIT .\" .Dd February 23, 2018 .Dt GBZ80 7 .Os .Sh NAME .Nm gbz80 .Nd CPU opcode reference .Sh DESCRIPTION This is the list of opcodes supported by .Xr rgbasm 1 , including a short description, the number of bytes needed to encode them and the number of CPU cycles at 1MHz (or 2MHz in GBC dual speed mode) needed to complete them. .Pp Note: All arithmetic/logic operations that use register .Sy A as destination can omit the destination as it is assumed to be register .Sy A by default. The following two lines have the same effect: .Pp .Bd -literal -offset indent OR A,B OR B .Ed .Pp .Sh LEGEND List of abbreviations used in this document. .Bl -tag .It Ar r8 Any of the 8-bit registers .Pq Sy A , B , C , D , E , H , L . .It Ar r16 Any of the general-purpose 16-bit registers .Pq Sy BC , DE , HL . .It Ar n8 8-bit integer constant. .It Ar n16 16-bit integer constant. .It Ar e8 8-bit offset .Po Sy -128 to .Sy 127 .Pc . .It Ar u3 3-bit unsigned integer constant .Po Sy 0 to .Sy 7 .Pc . .It Ar cc Condition codes: .Bl -tag -compact .It Sy Z Execute if Z is set. .It Sy NZ Execute if Z is not set. .It Sy C Execute if C is set. .It Sy NC Execute if C is not set. .El .It Ar vec One of the .Sy RST vectors .Po Sy 0x00 , 0x08 , 0x10 , 0x18 , 0x20 , 0x28 , 0x30 and .Sy 0x38 .Pc . .El .Sh INSTRUCTION OVERVIEW .Ss 8-bit Arithmetic and Logic Instructions .Bl -inset -compact .It Sx ADC A,r8 .It Sx ADC A,[HL] .It Sx ADC A,n8 .It Sx ADD A,r8 .It Sx ADD A,[HL] .It Sx ADD A,n8 .It Sx AND A,r8 .It Sx AND A,[HL] .It Sx AND A,n8 .It Sx CP A,r8 .It Sx CP A,[HL] .It Sx CP A,n8 .It Sx DEC r8 .It Sx DEC [HL] .It Sx INC r8 .It Sx INC [HL] .It Sx OR A,r8 .It Sx OR A,[HL] .It Sx OR A,n8 .It Sx SBC A,r8 .It Sx SBC A,[HL] .It Sx SBC A,n8 .It Sx SUB A,r8 .It Sx SUB A,[HL] .It Sx SUB A,n8 .It Sx XOR A,r8 .It Sx XOR A,[HL] .It Sx XOR A,n8 .El .Ss 16-bit Arithmetic Instructions .Bl -inset -compact .It Sx ADD HL,r16 .It Sx DEC r16 .It Sx INC r16 .El .Ss Bit Operations Instructions .Bl -inset -compact .It Sx BIT u3,r8 .It Sx BIT u3,[HL] .It Sx RES u3,r8 .It Sx RES u3,[HL] .It Sx SET u3,r8 .It Sx SET u3,[HL] .It Sx SWAP r8 .It Sx SWAP [HL] .El .Ss Bit Shift Instructions .Bl -inset -compact .It Sx RL r8 .It Sx RL [HL] .It Sx RLA .It Sx RLC r8 .It Sx RLC [HL] .It Sx RLCA .It Sx RR r8 .It Sx RR [HL] .It Sx RRA .It Sx RRC r8 .It Sx RRC [HL] .It Sx RRCA .It Sx SLA r8 .It Sx SLA [HL] .It Sx SRA r8 .It Sx SRA [HL] .It Sx SRL r8 .It Sx SRL [HL] .El .Ss Load Instructions .Bl -inset -compact .It Sx LD r8,r8 .It Sx LD r8,n8 .It Sx LD r16,n16 .It Sx LD [HL],r8 .It Sx LD [HL],n8 .It Sx LD r8,[HL] .It Sx LD [r16],A .It Sx LD [n16],A .It Sx LDH [n16],A .It Sx LDH [C],A .It Sx LD A,[r16] .It Sx LD A,[n16] .It Sx LDH A,[n16] .It Sx LDH A,[C] .It Sx LD [HLI],A .It Sx LD [HLD],A .It Sx LD A,[HLI] .It Sx LD A,[HLD] .El .Ss Jumps and Subroutines .Bl -inset -compact .It Sx CALL n16 .It Sx CALL cc,n16 .It Sx JP HL .It Sx JP n16 .It Sx JP cc,n16 .It Sx JR e8 .It Sx JR cc,e8 .It Sx RET cc .It Sx RET .It Sx RETI .It Sx RST vec .El .Ss Stack Operations Instructions .Bl -inset -compact .It Sx ADD HL,SP .It Sx ADD SP,e8 .It Sx DEC SP .It Sx INC SP .It Sx LD SP,n16 .It Sx LD [n16],SP .It Sx LD HL,SP+e8 .It Sx LD SP,HL .It Sx POP AF .It Sx POP r16 .It Sx PUSH AF .It Sx PUSH r16 .El .Ss Miscellaneous Instructions .Bl -inset -compact .It Sx CCF .It Sx CPL .It Sx DAA .It Sx DI .It Sx EI .It Sx HALT .It Sx NOP .It Sx SCF .It Sx STOP .El .Sh INSTRUCTION REFERENCE .Ss ADC A,r8 Add the value in .Ar r8 plus the carry flag to .Sy A . .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy N 0 .It Sy H Set if overflow from bit 3. .It Sy C Set if overflow from bit 7. .El .Ss ADC A,[HL] Add the byte pointed to by .Sy HL plus the carry flag to .Sy A . .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: See .Sx ADC A,r8 .Ss ADC A,n8 Add the value .Ar n8 plus the carry flag to .Sy A . .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: See .Sx ADC A,r8 .Ss ADD A,r8 Add the value in .Ar r8 to .Sy A . .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy N 0 .It Sy H Set if overflow from bit 3. .It Sy C Set if overflow from bit 7. .El .Ss ADD A,[HL] Add the byte pointed to by .Sy HL to .Sy A . .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: See .Sx ADD A,r8 .Ss ADD A,n8 Add the value .Ar n8 to .Sy A . .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: See .Sx ADD A,r8 .Ss ADD HL,r16 Add the value in .Ar r16 to .Sy HL . .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy N 0 .It Sy H Set if overflow from bit 11. .It Sy C Set if overflow from bit 15. .El .Ss ADD HL,SP Add the value in .Sy SP to .Sy HL . .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: See .Sx ADD HL,r16 .Ss ADD SP,e8 Add the signed value .Ar e8 to .Sy SP . .Pp Cycles: 4 .Pp Bytes: 2 .Pp Flags: .Bl -hang -compact .It Sy Z 0 .It Sy N 0 .It Sy H Set if overflow from bit 3. .It Sy C Set if overflow from bit 7. .El .Ss AND A,r8 Bitwise AND between the value in .Ar r8 and .Sy A . .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy N 0 .It Sy H 1 .It Sy C 0 .El .Ss AND A,[HL] Bitwise AND between the byte pointed to by .Sy HL and .Sy A . .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: See .Sx AND A,r8 .Ss AND A,n8 Bitwise AND between the value in .Ar n8 and .Sy A . .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: See .Sx AND A,r8 .Ss BIT u3,r8 Test bit .Ar u3 in register .Ar r8 , set the zero flag if bit not set. .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: .Bl -hang -compact .It Sy Z Set if the selected bit is 0. .It Sy N 0 .It Sy H 1 .El .Ss BIT u3,[HL] Test bit .Ar u3 in the byte pointed by .Sy HL , set the zero flag if bit not set. .Pp Cycles: 3 .Pp Bytes: 2 .Pp Flags: See .Sx BIT u3,r8 .Ss CALL n16 Call address .Ar n16 . This pushes the address of the instruction after the .Sy CALL on the stack, such that .Sx RET can pop it later; then, it executes an implicit .Sx JP n16 . .Pp Cycles: 6 .Pp Bytes: 3 .Pp Flags: None affected. .Ss CALL cc,n16 Call address .Ar n16 if condition .Ar cc is met. .Pp Cycles: 6 taken / 3 untaken .Pp Bytes: 3 .Pp Flags: None affected. .Ss CCF Complement Carry Flag. .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy N 0 .It Sy H 0 .It Sy C Inverted. .El .Ss CP A,r8 Subtract the value in .Ar r8 from .Sy A and set flags accordingly, but don't store the result. This is useful for ComParing values. .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy N 1 .It Sy H Set if borrow from bit 4. .It Sy C Set if borrow (i.e. if .Ar r8 > .Sy A ) . .El .Ss CP A,[HL] Subtract the byte pointed to by .Sy HL from .Sy A and set flags accordingly, but don't store the result. .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: See .Sx CP A,r8 .Ss CP A,n8 Subtract the value .Ar n8 from .Sy A and set flags accordingly, but don't store the result. .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: See .Sx CP A,r8 .Ss CPL ComPLement accumulator .Po Sy A = .Sy ~A .Pc . .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy N 1 .It Sy H 1 .El .Ss DAA Decimal Adjust Accumulator to get a correct BCD representation after an arithmetic instruction. .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy H 0 .It Sy C Set or reset depending on the operation. .El .Ss DEC r8 Decrement value in register .Ar r8 by 1. .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy N 1 .It Sy H Set if borrow from bit 4. .El .Ss DEC [HL] Decrement the byte pointed to by .Sy HL by 1. .Pp Cycles: 3 .Pp Bytes: 1 .Pp Flags: See .Sx DEC r8 .Ss DEC r16 Decrement value in register .Ar r16 by 1. .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: None affected. .Ss DEC SP Decrement value in register .Sy SP by 1. .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: None affected. .Ss DI Disable Interrupts by clearing the .Sy IME flag. .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: None affected. .Ss EI Enable Interrupts by setting the .Sy IME flag. The flag is only set .Em after the instruction following .Sy EI . .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: None affected. .Ss HALT Enter CPU low-power consumption mode until an interrupt occurs. The exact behavior of this instruction depends on the state of the .Sy IME flag. .Bl -tag -width indent .It Sy IME No set The CPU enters low-power mode until .Em after an interrupt is about to be serviced. The handler is executed normally, and the CPU resumes execution after the .Ic HALT when that returns. .It Sy IME No not set The behavior depends on whether an interrupt is pending (i.e.\& .Ql [IE] & [IF] is non-zero). .Bl -tag -width indent .It None pending As soon as an interrupt becomes pending, the CPU resumes execution. This is like the above, except that the handler is .Em not called. .It Some pending The CPU continues execution after the .Ic HALT , but the byte after it is read twice in a row .Po .Sy PC is not incremented, due to a hardware bug .Pc . .El .El .Pp Cycles: - .Pp Bytes: 1 .Pp Flags: None affected. .Ss INC r8 Increment value in register .Ar r8 by 1. .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy N 0 .It Sy H Set if overflow from bit 3. .El .Ss INC [HL] Increment the byte pointed to by .Sy HL by 1. .Pp Cycles: 3 .Pp Bytes: 1 .Pp Flags: See .Sx INC r8 .Ss INC r16 Increment value in register .Ar r16 by 1. .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: None affected. .Ss INC SP Increment value in register .Sy SP by 1. .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: None affected. .Ss JP n16 Jump to address .Ar n16 ; effectively, store .Ar n16 into .Sy PC . .Pp Cycles: 4 .Pp Bytes: 3 .Pp Flags: None affected. .Ss JP cc,n16 Jump to address .Ar n16 if condition .Ar cc is met. .Pp Cycles: 4 taken / 3 untaken .Pp Bytes: 3 .Pp Flags: None affected. .Ss JP HL Jump to address in .Sy HL ; effectively, load .Sy PC with value in register .Sy HL . .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: None affected. .Ss JR e8 Relative Jump by adding .Ar e8 to the address of the instruction following the .Sy JR . To clarify, an operand of 0 is equivalent to no jumping. .Pp Cycles: 3 .Pp Bytes: 2 .Pp Flags: None affected. .Ss JR cc,e8 Relative Jump by adding .Ar e8 to the current address if condition .Ar cc is met. .Pp Cycles: 3 taken / 2 untaken .Pp Bytes: 2 .Pp Flags: None affected. .Ss LD r8,r8 Load (copy) value in register on the right into register on the left. .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: None affected. .Ss LD r8,n8 Load value .Ar n8 into register .Ar r8 . .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: None affected. .Ss LD r16,n16 Load value .Ar n16 into register .Ar r16 . .Pp Cycles: 3 .Pp Bytes: 3 .Pp Flags: None affected. .Ss LD [HL],r8 Store value in register .Ar r8 into byte pointed to by register .Sy HL . .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: None affected. .Ss LD [HL],n8 Store value .Ar n8 into byte pointed to by register .Sy HL . .Pp Cycles: 3 .Pp Bytes: 2 .Pp Flags: None affected. .Ss LD r8,[HL] Load value into register .Ar r8 from byte pointed to by register .Sy HL . .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: None affected. .Ss LD [r16],A Store value in register .Sy A into byte pointed to by register .Ar r16 . .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: None affected. .Ss LD [n16],A Store value in register .Sy A into byte at address .Ar n16 . .Pp Cycles: 4 .Pp Bytes: 3 .Pp Flags: None affected. .Ss LDH [n16],A Store value in register .Sy A into byte at address .Ar n16 , provided it is between .Ad $FF00 and .Ad $FFFF . .Pp Cycles: 3 .Pp Bytes: 2 .Pp Flags: None affected. .Pp This is sometimes written as .Ql ldio [n16], a , or .Ql ld [$ff00+n8], a . .Ss LDH [C],A Store value in register .Sy A into byte at address .Ad $FF00+C . .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: None affected. .Pp This is sometimes written as .Ql ldio [c], a , or .Ql ld [$ff00+c], a . .Ss LD A,[r16] Load value in register .Sy A from byte pointed to by register .Ar r16 . .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: None affected. .Ss LD A,[n16] Load value in register .Sy A from byte at address .Ar n16 . .Pp Cycles: 4 .Pp Bytes: 3 .Pp Flags: None affected. .Ss LDH A,[n16] Load value in register .Sy A from byte at address .Ar n16 , provided it is between .Ad $FF00 and .Ad $FFFF . .Pp Cycles: 3 .Pp Bytes: 2 .Pp Flags: None affected. .Pp This is sometimes written as .Ql ldio a, [n16] , or .Ql ld a, [$ff00+n8] . .Ss LDH A,[C] Load value in register .Sy A from byte at address .Ad $FF00+c . .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: None affected. .Pp This is sometimes written as .Ql ldio a, [c] , or .Ql ld a, [$ff00+c] . .Ss LD [HLI],A Store value in register .Sy A into byte pointed by .Sy HL and increment .Sy HL afterwards. .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: None affected. .Ss LD [HLD],A Store value in register .Sy A into byte pointed by .Sy HL and decrement .Sy HL afterwards. .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: None affected. .Ss LD A,[HLD] Load value into register .Sy A from byte pointed by .Sy HL and decrement .Sy HL afterwards. .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: None affected. .Ss LD A,[HLI] Load value into register .Sy A from byte pointed by .Sy HL and increment .Sy HL afterwards. .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: None affected. .Ss LD SP,n16 Load value .Ar n16 into register .Sy SP . .Pp Cycles: 3 .Pp Bytes: 3 .Pp Flags: None affected. .Ss LD [n16],SP Store .Sy SP & $FF at address .Ar n16 and .Sy SP >> 8 at address .Ar n16 + 1. .Pp Cycles: 5 .Pp Bytes: 3 .Pp Flags: None affected. .Ss LD HL,SP+e8 Add the signed value .Ar e8 to .Sy SP and store the result in .Sy HL . .Pp Cycles: 3 .Pp Bytes: 2 .Pp Flags: .Bl -hang -compact .It Sy Z 0 .It Sy N 0 .It Sy H Set if overflow from bit 3. .It Sy C Set if overflow from bit 7. .El .Ss LD SP,HL Load register .Sy HL into register .Sy SP . .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: None affected. .Ss NOP No OPeration. .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: None affected. .Ss OR A,r8 Store into .Sy A the bitwise OR of the value in .Ar r8 and .Sy A . .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy N 0 .It Sy H 0 .It Sy C 0 .El .Ss OR A,[HL] Store into .Sy A the bitwise OR of the byte pointed to by .Sy HL and .Sy A . .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: See .Sx OR A,r8 .Ss OR A,n8 Store into .Sy A the bitwise OR of .Ar n8 and .Sy A . .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: See .Sx OR A,r8 .Ss POP AF Pop register .Sy AF from the stack. This is roughly equivalent to the following .Em imaginary instructions: .Bd -literal -offset indent inc sp ld a, [sp] inc sp ld f, [sp] ; See below for individual flags .Ed .Pp Cycles: 3 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy Z Set from bit 7 of the popped low byte. .It Sy N Set from bit 6 of the popped low byte. .It Sy H Set from bit 5 of the popped low byte. .It Sy C Set from bit 4 of the popped low byte. .El .Ss POP r16 Pop register .Ar r16 from the stack. This is roughly equivalent to the following .Em imaginary instructions: .Bd -literal -offset indent ld LOW(r16), [sp] ; C, E or L inc sp ld HIGH(r16), [sp] ; B, D or H inc sp .Ed .Pp Cycles: 3 .Pp Bytes: 1 .Pp Flags: None affected. .Ss PUSH AF Push register .Sy AF into the stack. This is roughly equivalent to the following .Em imaginary instructions: .Bd -literal -offset indent dec sp ld [sp], a dec sp ld [sp], flag_Z << 7 | flag_N << 6 | flag_H << 5 | flag_C << 4 .Ed .Pp Cycles: 4 .Pp Bytes: 1 .Pp Flags: None affected. .Ss PUSH r16 Push register .Ar r16 into the stack. This is roughly equivalent to the following .Em imaginary instructions: .Bd -literal -offset indent dec sp ld [sp], HIGH(r16) ; B, D or H dec sp ld [sp], LOW(r16) ; C, E or L .Ed .Pp Cycles: 4 .Pp Bytes: 1 .Pp Flags: None affected. .Ss RES u3,r8 Set bit .Ar u3 in register .Ar r8 to 0. Bit 0 is the rightmost one, bit 7 the leftmost one. .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: None affected. .Ss RES u3,[HL] Set bit .Ar u3 in the byte pointed by .Sy HL to 0. Bit 0 is the rightmost one, bit 7 the leftmost one. .Pp Cycles: 4 .Pp Bytes: 2 .Pp Flags: None affected. .Ss RET Return from subroutine. This is basically a .Sy POP PC (if such an instruction existed). See .Sx POP r16 for an explanation of how .Sy POP works. .Pp Cycles: 4 .Pp Bytes: 1 .Pp Flags: None affected. .Ss RET cc Return from subroutine if condition .Ar cc is met. .Pp Cycles: 5 taken / 2 untaken .Pp Bytes: 1 .Pp Flags: None affected. .Ss RETI Return from subroutine and enable interrupts. This is basically equivalent to executing .Sx EI then .Sx RET , meaning that .Sy IME is set right after this instruction. .Pp Cycles: 4 .Pp Bytes: 1 .Pp Flags: None affected. .Ss RL r8 Rotate bits in register .Ar r8 left through carry. .Pp .D1 C <- [7 <- 0] <- C .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy N 0 .It Sy H 0 .It Sy C Set according to result. .El .Ss RL [HL] Rotate byte pointed to by .Sy HL left through carry. .Pp .D1 C <- [7 <- 0] <- C .Pp Cycles: 4 .Pp Bytes: 2 .Pp Flags: See .Sx RL r8 .Ss RLA Rotate register .Sy A left through carry. .Pp .D1 C <- [7 <- 0] <- C .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy Z 0 .It Sy N 0 .It Sy H 0 .It Sy C Set according to result. .El .Ss RLC r8 Rotate register .Ar r8 left. .Pp .D1 C <- [7 <- 0] <- [7] .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy N 0 .It Sy H 0 .It Sy C Set according to result. .El .Ss RLC [HL] Rotate byte pointed to by .Sy HL left. .Pp .D1 C <- [7 <- 0] <- [7] .Pp Cycles: 4 .Pp Bytes: 2 .Pp Flags: See .Sx RLC r8 .Ss RLCA Rotate register .Sy A left. .Pp .D1 C <- [7 <- 0] <- [7] .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy Z 0 .It Sy N 0 .It Sy H 0 .It Sy C Set according to result. .El .Ss RR r8 Rotate register .Ar r8 right through carry. .Pp .D1 C -> [7 -> 0] -> C .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy N 0 .It Sy H 0 .It Sy C Set according to result. .El .Ss RR [HL] Rotate byte pointed to by .Sy HL right through carry. .Pp .D1 C -> [7 -> 0] -> C .Pp Cycles: 4 .Pp Bytes: 2 .Pp Flags: See .Sx RR r8 .Ss RRA Rotate register .Sy A right through carry. .Pp .D1 C -> [7 -> 0] -> C .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy Z 0 .It Sy N 0 .It Sy H 0 .It Sy C Set according to result. .El .Ss RRC r8 Rotate register .Ar r8 right. .Pp .D1 [0] -> [7 -> 0] -> C .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy N 0 .It Sy H 0 .It Sy C Set according to result. .El .Ss RRC [HL] Rotate byte pointed to by .Sy HL right. .Pp .D1 [0] -> [7 -> 0] -> C .Pp Cycles: 4 .Pp Bytes: 2 .Pp Flags: See .Sx RRC r8 .Ss RRCA Rotate register .Sy A right. .Pp .D1 [0] -> [7 -> 0] -> C .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy Z 0 .It Sy N 0 .It Sy H 0 .It Sy C Set according to result. .El .Ss RST vec Call address .Ar vec . This is a shorter and faster equivalent to .Sx CALL for suitable values of .Ar vec . .Pp Cycles: 4 .Pp Bytes: 1 .Pp Flags: None affected. .Ss SBC A,r8 Subtract the value in .Ar r8 and the carry flag from .Sy A . .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy N 1 .It Sy H Set if borrow from bit 4. .It Sy C Set if borrow (i.e. if .Po Ar r8 + carry .Pc > .Sy A ) . .El .Ss SBC A,[HL] Subtract the byte pointed to by .Sy HL and the carry flag from .Sy A . .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: See .Sx SBC A,r8 .Ss SBC A,n8 Subtract the value .Ar n8 and the carry flag from .Sy A . .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: See .Sx SBC A,r8 .Ss SCF Set Carry Flag. .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy N 0 .It Sy H 0 .It Sy C 1 .El .Ss SET u3,r8 Set bit .Ar u3 in register .Ar r8 to 1. Bit 0 is the rightmost one, bit 7 the leftmost one. .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: None affected. .Ss SET u3,[HL] Set bit .Ar u3 in the byte pointed by .Sy HL to 1. Bit 0 is the rightmost one, bit 7 the leftmost one. .Pp Cycles: 4 .Pp Bytes: 2 .Pp Flags: None affected. .Ss SLA r8 Shift Left Arithmetic register .Ar r8 . .Pp .D1 C <- [7 <- 0] <- 0 .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy N 0 .It Sy H 0 .It Sy C Set according to result. .El .Ss SLA [HL] Shift Left Arithmetic byte pointed to by .Sy HL . .Pp .D1 C <- [7 <- 0] <- 0 .Pp Cycles: 4 .Pp Bytes: 2 .Pp Flags: See .Sx SLA r8 .Ss SRA r8 Shift Right Arithmetic register .Ar r8 . .Pp .D1 [7] -> [7 -> 0] -> C .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy N 0 .It Sy H 0 .It Sy C Set according to result. .El .Ss SRA [HL] Shift Right Arithmetic byte pointed to by .Sy HL . .Pp .D1 [7] -> [7 -> 0] -> C .Pp Cycles: 4 .Pp Bytes: 2 .Pp Flags: See .Sx SRA r8 .Ss SRL r8 Shift Right Logic register .Ar r8 . .Pp .D1 0 -> [7 -> 0] -> C .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy N 0 .It Sy H 0 .It Sy C Set according to result. .El .Ss SRL [HL] Shift Right Logic byte pointed to by .Sy HL . .Pp .D1 0 -> [7 -> 0] -> C .Pp Cycles: 4 .Pp Bytes: 2 .Pp Flags: See .Sx SRA r8 .Ss STOP Enter CPU very low power mode. Also used to switch between double and normal speed CPU modes in GBC. .Pp Cycles: - .Pp Bytes: 2 .Pp Flags: None affected. .Ss SUB A,r8 Subtract the value in .Ar r8 from .Sy A . .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy N 1 .It Sy H Set if borrow from bit 4. .It Sy C Set if borrow (set if .Ar r8 > .Sy A ) . .El .Ss SUB A,[HL] Subtract the byte pointed to by .Sy HL from .Sy A . .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: See .Sx SUB A,r8 .Ss SUB A,n8 Subtract the value .Ar n8 from .Sy A . .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: See .Sx SUB A,r8 .Ss SWAP r8 Swap upper 4 bits in register .Ar r8 and the lower 4 ones. .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy N 0 .It Sy H 0 .It Sy C 0 .El .Ss SWAP [HL] Swap upper 4 bits in the byte pointed by .Sy HL and the lower 4 ones. .Pp Cycles: 4 .Pp Bytes: 2 .Pp Flags: See .Sx SWAP r8 .Ss XOR A,r8 Bitwise XOR between the value in .Ar r8 and .Sy A . .Pp Cycles: 1 .Pp Bytes: 1 .Pp Flags: .Bl -hang -compact .It Sy Z Set if result is 0. .It Sy N 0 .It Sy H 0 .It Sy C 0 .El .Ss XOR A,[HL] Bitwise XOR between the byte pointed to by .Sy HL and .Sy A . .Pp Cycles: 2 .Pp Bytes: 1 .Pp Flags: See .Sx XOR A,r8 .Ss XOR A,n8 Bitwise XOR between the value in .Ar n8 and .Sy A . .Pp Cycles: 2 .Pp Bytes: 2 .Pp Flags: See .Sx XOR A,r8 .Sh SEE ALSO .Xr rgbasm 1 , .Xr rgbds 7 .Sh HISTORY .Nm rgbds was originally written by Carsten S\(/orensen as part of the ASMotor package, and was later packaged in RGBDS by Justin Lloyd. It is now maintained by a number of contributors at .Lk https://github.com/rednex/rgbds .