RGBDS v0.4.1 documentation (back)

GBZ80(7) | Miscellaneous Information Manual | GBZ80(7) |

# NAME

`gbz80`

—
# DESCRIPTION

This is the list of opcodes supported by 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.Note: All arithmetic/logic operations that use register
**A** as destination can omit the destination as it is assumed
to be register **A** by default. The following two lines have
the same effect:

OR A,B OR B

# LEGEND

List of abbreviations used in this document.`r8`- Any of the 8-bit registers (
**A**,**B**,**C**,**D**,**E**,**H**,**L**). `r16`- Any of the general-purpose 16-bit registers (
**BC**,**DE**,**HL**). `n8`- 8-bit integer constant.
`n16`- 16-bit integer constant.
`e8`- 8-bit offset (
**-128**to**127**). `u3`- 3-bit unsigned integer constant (
**0**to**7**). `cc`- Condition codes:
**Z**- Execute if Z is set.
**NZ**- Execute if Z is not set.
**C**- Execute if C is set.
**NC**- Execute if C is not set.

`vec`- One of the
**RST**vectors (**0x00**,**0x08**,**0x10**,**0x18**,**0x20**,**0x28**,**0x30**and**0x38**).

# INSTRUCTION OVERVIEW

## 8-bit Arithmetic and Logic Instructions

## 16-bit Arithmetic Instructions

## Bit Operations Instructions

## Bit Shift Instructions

## Load Instructions

## Jumps and Subroutines

## Stack Operations Instructions

## Miscellaneous Instructions

# INSTRUCTION REFERENCE

## ADC A,r8

Add the value in`r8`plus the carry flag to

**A**.

Cycles: 1

Bytes: 1

Flags:

**Z**- Set if result is 0.
**N**- 0
**H**- Set if overflow from bit 3.
**C**- Set if overflow from bit 7.

## ADC A,[HL]

Add the byte pointed to by**HL**plus the carry flag to

**A**.

Cycles: 2

Bytes: 1

Flags: See ADC A,r8

## ADC A,n8

Add the value`n8`plus the carry flag to

**A**.

Cycles: 2

Bytes: 2

Flags: See ADC A,r8

## ADD A,r8

Add the value in`r8`to

**A**.

Cycles: 1

Bytes: 1

Flags:

**Z**- Set if result is 0.
**N**- 0
**H**- Set if overflow from bit 3.
**C**- Set if overflow from bit 7.

## ADD A,[HL]

Add the byte pointed to by**HL**to

**A**.

Cycles: 2

Bytes: 1

Flags: See ADD A,r8

## ADD A,n8

Add the value`n8`to

**A**.

Cycles: 2

Bytes: 2

Flags: See ADD A,r8

## ADD HL,r16

Add the value in`r16`to

**HL**.

Cycles: 2

Bytes: 1

Flags:

**N**- 0
**H**- Set if overflow from bit 11.
**C**- Set if overflow from bit 15.

## ADD HL,SP

Add the value in**SP**to

**HL**.

Cycles: 2

Bytes: 1

Flags: See ADD HL,r16

## ADD SP,e8

Add the signed value`e8`to

**SP**.

Cycles: 4

Bytes: 2

Flags:

**Z**- 0
**N**- 0
**H**- Set if overflow from bit 3.
**C**- Set if overflow from bit 7.

## AND A,r8

Bitwise AND between the value in`r8`and

**A**.

Cycles: 1

Bytes: 1

Flags:

**Z**- Set if result is 0.
**N**- 0
**H**- 1
**C**- 0

## AND A,[HL]

Bitwise AND between the byte pointed to by**HL**and

**A**.

Cycles: 2

Bytes: 1

Flags: See AND A,r8

## AND A,n8

Bitwise AND between the value in`n8`and

**A**.

Cycles: 2

Bytes: 2

Flags: See AND A,r8

## BIT u3,r8

Test bit`u3`in register

`r8`, set the zero flag if bit not set.

Cycles: 2

Bytes: 2

Flags:

**Z**- Set if the selected bit is 0.
**N**- 0
**H**- 1

## BIT u3,[HL]

Test bit`u3`in the byte pointed by

**HL**, set the zero flag if bit not set.

Cycles: 3

Bytes: 2

Flags: See BIT u3,r8

## CALL n16

Call address`n16`. This pushes the address of the instruction after the

**CALL**on the stack, such that RET can pop it later; then, it executes an implicit JP n16.

Cycles: 6

Bytes: 3

Flags: None affected.

## CALL cc,n16

Call address`n16`if condition

`cc`is met.

Cycles: 6 taken / 3 untaken

Bytes: 3

Flags: None affected.

## CCF

Complement Carry Flag.Cycles: 1

Bytes: 1

Flags:

**N**- 0
**H**- 0
**C**- Inverted.

## CP A,r8

Subtract the value in`r8`from

**A**and set flags accordingly, but don't store the result. This is useful for ComParing values.

Cycles: 1

Bytes: 1

Flags:

**Z**- Set if result is 0.
**N**- 1
**H**- Set if borrow from bit 4.
**C**- Set if borrow (i.e. if
`r8`>**A**).

## CP A,[HL]

Subtract the byte pointed to by**HL**from

**A**and set flags accordingly, but don't store the result.

Cycles: 2

Bytes: 1

Flags: See CP A,r8

## CP A,n8

Subtract the value`n8`from

**A**and set flags accordingly, but don't store the result.

Cycles: 2

Bytes: 2

Flags: See CP A,r8

## CPL

ComPLement accumulator (**A**=

**~A**).

Cycles: 1

Bytes: 1

Flags:

**N**- 1
**H**- 1

## DAA

Decimal Adjust Accumulator to get a correct BCD representation after an arithmetic instruction.Cycles: 1

Bytes: 1

Flags:

**Z**- Set if result is 0.
**H**- 0
**C**- Set or reset depending on the operation.

## DEC r8

Decrement value in register`r8`by 1.

Cycles: 1

Bytes: 1

Flags:

**Z**- Set if result is 0.
**N**- 1
**H**- Set if borrow from bit 4.

## DEC [HL]

Decrement the byte pointed to by**HL**by 1.

Cycles: 3

Bytes: 1

Flags: See DEC r8

## DEC r16

Decrement value in register`r16`by 1.

Cycles: 2

Bytes: 1

Flags: None affected.

## DEC SP

Decrement value in register**SP**by 1.

Cycles: 2

Bytes: 1

Flags: None affected.

## DI

Disable Interrupts by clearing the**IME**flag.

Cycles: 1

Bytes: 1

Flags: None affected.

## EI

Enable Interrupts by setting the**IME**flag. The flag is only set

*after*the instruction following

**EI**.

Cycles: 1

Bytes: 1

Flags: None affected.

## HALT

Enter CPU low-power consumption mode until an interrupt occurs. The exact behavior of this instruction depends on the state of the**IME**flag.

**IME**set- The CPU enters low-power mode until
*after*an interrupt is about to be serviced. The handler is executed normally, and the CPU resumes execution after the`HALT`

when that returns. **IME**not set- The behavior depends on whether an interrupt is pending (i.e.
‘
`[IE] & [IF]`

’ is non-zero).- None pending
- As soon as an interrupt becomes pending, the CPU resumes execution.
This is like the above, except that the handler is
*not*called. - Some pending
- The CPU continues execution after the
`HALT`

, but the byte after it is read twice in a row (**PC**is not incremented, due to a hardware bug).

Cycles: -

Bytes: 1

Flags: None affected.

## INC r8

Increment value in register`r8`by 1.

Cycles: 1

Bytes: 1

Flags:

**Z**- Set if result is 0.
**N**- 0
**H**- Set if overflow from bit 3.

## INC [HL]

Increment the byte pointed to by**HL**by 1.

Cycles: 3

Bytes: 1

Flags: See INC r8

## INC r16

Increment value in register`r16`by 1.

Cycles: 2

Bytes: 1

Flags: None affected.

## INC SP

Increment value in register**SP**by 1.

Cycles: 2

Bytes: 1

Flags: None affected.

## JP n16

Jump to address`n16`; effectively, store

`n16`into

**PC**.

Cycles: 4

Bytes: 3

Flags: None affected.

## JP cc,n16

Jump to address`n16`if condition

`cc`is met.

Cycles: 4 taken / 3 untaken

Bytes: 3

Flags: None affected.

## JP HL

Jump to address in**HL**; effectively, load

**PC**with value in register

**HL**.

Cycles: 1

Bytes: 1

Flags: None affected.

## JR e8

Relative Jump by adding`e8`to the address of the instruction following the

**JR**. To clarify, an operand of 0 is equivalent to no jumping.

Cycles: 3

Bytes: 2

Flags: None affected.

## JR cc,e8

Relative Jump by adding`e8`to the current address if condition

`cc`is met.

Cycles: 3 taken / 2 untaken

Bytes: 2

Flags: None affected.

## LD r8,r8

Load (copy) value in register on the right into register on the left.Cycles: 1

Bytes: 1

Flags: None affected.

## LD r8,n8

Load value`n8`into register

`r8`.

Cycles: 2

Bytes: 2

Flags: None affected.

## LD r16,n16

Load value`n16`into register

`r16`.

Cycles: 3

Bytes: 3

Flags: None affected.

## LD [HL],r8

Store value in register`r8`into byte pointed to by register

**HL**.

Cycles: 2

Bytes: 1

Flags: None affected.

## LD [HL],n8

Store value`n8`into byte pointed to by register

**HL**.

Cycles: 3

Bytes: 2

Flags: None affected.

## LD r8,[HL]

Load value into register`r8`from byte pointed to by register

**HL**.

Cycles: 2

Bytes: 1

Flags: None affected.

## LD [r16],A

Store value in register**A**into byte pointed to by register

`r16`.

Cycles: 2

Bytes: 1

Flags: None affected.

## LD [n16],A

Store value in register**A**into byte at address

`n16`.

Cycles: 4

Bytes: 3

Flags: None affected.

## LDH [n16],A

Store value in register**A**into byte at address

`n16`, provided it is between $FF00 and $FFFF.

Cycles: 3

Bytes: 2

Flags: None affected.

This is sometimes written as ‘```
ldio [n16],
a
```

’, or ‘```
ld [$ff00+n8],
a
```

’.

## LDH [C],A

Store value in register**A**into byte at address $FF00+C.

Cycles: 2

Bytes: 1

Flags: None affected.

This is sometimes written as ‘```
ldio [c],
a
```

’, or ‘```
ld [$ff00+c],
a
```

’.

## LD A,[r16]

Load value in register**A**from byte pointed to by register

`r16`.

Cycles: 2

Bytes: 1

Flags: None affected.

## LD A,[n16]

Load value in register**A**from byte at address

`n16`.

Cycles: 4

Bytes: 3

Flags: None affected.

## LDH A,[n16]

Load value in register**A**from byte at address

`n16`, provided it is between $FF00 and $FFFF.

Cycles: 3

Bytes: 2

Flags: None affected.

This is sometimes written as ‘```
ldio a,
[n16]
```

’, or ‘```
ld a,
[$ff00+n8]
```

’.

## LDH A,[C]

Load value in register**A**from byte at address $FF00+c.

Cycles: 2

Bytes: 1

Flags: None affected.

This is sometimes written as ‘```
ldio a,
[c]
```

’, or ‘```
ld a,
[$ff00+c]
```

’.

## LD [HLI],A

Store value in register**A**into byte pointed by

**HL**and increment

**HL**afterwards.

Cycles: 2

Bytes: 1

Flags: None affected.

## LD [HLD],A

Store value in register**A**into byte pointed by

**HL**and decrement

**HL**afterwards.

Cycles: 2

Bytes: 1

Flags: None affected.

## LD A,[HLD]

Load value into register**A**from byte pointed by

**HL**and decrement

**HL**afterwards.

Cycles: 2

Bytes: 1

Flags: None affected.

## LD A,[HLI]

Load value into register**A**from byte pointed by

**HL**and increment

**HL**afterwards.

Cycles: 2

Bytes: 1

Flags: None affected.

## LD SP,n16

Load value`n16`into register

**SP**.

Cycles: 3

Bytes: 3

Flags: None affected.

## LD [n16],SP

Store**SP & $FF**at address

`n16`and

**SP >> 8**at address

`n16`+ 1.

Cycles: 5

Bytes: 3

Flags: None affected.

## LD HL,SP+e8

Add the signed value`e8`to

**SP**and store the result in

**HL**.

Cycles: 3

Bytes: 2

Flags:

**Z**- 0
**N**- 0
**H**- Set if overflow from bit 3.
**C**- Set if overflow from bit 7.

## LD SP,HL

Load register**HL**into register

**SP**.

Cycles: 2

Bytes: 1

Flags: None affected.

## NOP

No OPeration.Cycles: 1

Bytes: 1

Flags: None affected.

## OR A,r8

Store into**A**the bitwise OR of the value in

`r8`and

**A**.

Cycles: 1

Bytes: 1

Flags:

**Z**- Set if result is 0.
**N**- 0
**H**- 0
**C**- 0

## OR A,[HL]

Store into**A**the bitwise OR of the byte pointed to by

**HL**and

**A**.

Cycles: 2

Bytes: 1

Flags: See OR A,r8

## OR A,n8

Store into**A**the bitwise OR of

`n8`and

**A**.

Cycles: 2

Bytes: 2

Flags: See OR A,r8

## POP AF

Pop register**AF**from the stack. This is roughly equivalent to the following

*imaginary*instructions:

ld f, [sp] ; See below for individual flags inc sp ld a, [sp] inc sp

Cycles: 3

Bytes: 1

Flags:

**Z**- Set from bit 7 of the popped low byte.
**N**- Set from bit 6 of the popped low byte.
**H**- Set from bit 5 of the popped low byte.
**C**- Set from bit 4 of the popped low byte.

## POP r16

Pop register`r16`from the stack. This is roughly equivalent to the following

*imaginary*instructions:

ld LOW(r16), [sp] ; C, E or L inc sp ld HIGH(r16), [sp] ; B, D or H inc sp

Cycles: 3

Bytes: 1

Flags: None affected.

## PUSH AF

Push register**AF**into the stack. This is roughly equivalent to the following

*imaginary*instructions:

dec sp ld [sp], a dec sp ld [sp], flag_Z << 7 | flag_N << 6 | flag_H << 5 | flag_C << 4

Cycles: 4

Bytes: 1

Flags: None affected.

## PUSH r16

Push register`r16`into the stack. This is roughly equivalent to the following

*imaginary*instructions:

dec sp ld [sp], HIGH(r16) ; B, D or H dec sp ld [sp], LOW(r16) ; C, E or L

Cycles: 4

Bytes: 1

Flags: None affected.

## RES u3,r8

Set bit`u3`in register

`r8`to 0. Bit 0 is the rightmost one, bit 7 the leftmost one.

Cycles: 2

Bytes: 2

Flags: None affected.

## RES u3,[HL]

Set bit`u3`in the byte pointed by

**HL**to 0. Bit 0 is the rightmost one, bit 7 the leftmost one.

Cycles: 4

Bytes: 2

Flags: None affected.

## RET

Return from subroutine. This is basically a**POP PC**(if such an instruction existed). See POP r16 for an explanation of how

**POP**works.

Cycles: 4

Bytes: 1

Flags: None affected.

## RET cc

Return from subroutine if condition`cc`is met.

Cycles: 5 taken / 2 untaken

Bytes: 1

Flags: None affected.

## RETI

Return from subroutine and enable interrupts. This is basically equivalent to executing EI then RET, meaning that**IME**is set right after this instruction.

Cycles: 4

Bytes: 1

Flags: None affected.

## RL r8

Rotate bits in register`r8`left through carry.

Cycles: 2

Bytes: 2

Flags:

**Z**- Set if result is 0.
**N**- 0
**H**- 0
**C**- Set according to result.

## RL [HL]

Rotate byte pointed to by**HL**left through carry.

Cycles: 4

Bytes: 2

Flags: See RL r8

## RLA

Rotate register**A**left through carry.

Cycles: 1

Bytes: 1

Flags:

**Z**- 0
**N**- 0
**H**- 0
**C**- Set according to result.

## RLC r8

Rotate register`r8`left.

Cycles: 2

Bytes: 2

Flags:

**Z**- Set if result is 0.
**N**- 0
**H**- 0
**C**- Set according to result.

## RLC [HL]

Rotate byte pointed to by**HL**left.

Cycles: 4

Bytes: 2

Flags: See RLC r8

## RLCA

Rotate register**A**left.

Cycles: 1

Bytes: 1

Flags:

**Z**- 0
**N**- 0
**H**- 0
**C**- Set according to result.

## RR r8

Rotate register`r8`right through carry.

Cycles: 2

Bytes: 2

Flags:

**Z**- Set if result is 0.
**N**- 0
**H**- 0
**C**- Set according to result.

## RR [HL]

Rotate byte pointed to by**HL**right through carry.

Cycles: 4

Bytes: 2

Flags: See RR r8

## RRA

Rotate register**A**right through carry.

Cycles: 1

Bytes: 1

Flags:

**Z**- 0
**N**- 0
**H**- 0
**C**- Set according to result.

## RRC r8

Rotate register`r8`right.

Cycles: 2

Bytes: 2

Flags:

**Z**- Set if result is 0.
**N**- 0
**H**- 0
**C**- Set according to result.

## RRC [HL]

Rotate byte pointed to by**HL**right.

Cycles: 4

Bytes: 2

Flags: See RRC r8

## RRCA

Rotate register**A**right.

Cycles: 1

Bytes: 1

Flags:

**Z**- 0
**N**- 0
**H**- 0
**C**- Set according to result.

## RST vec

Call address`vec`. This is a shorter and faster equivalent to CALL for suitable values of

`vec`.

Cycles: 4

Bytes: 1

Flags: None affected.

## SBC A,r8

Subtract the value in`r8`and the carry flag from

**A**.

Cycles: 1

Bytes: 1

Flags:

**Z**- Set if result is 0.
**N**- 1
**H**- Set if borrow from bit 4.
**C**- Set if borrow (i.e. if (
`r8`+ carry) >**A**).

## SBC A,[HL]

Subtract the byte pointed to by**HL**and the carry flag from

**A**.

Cycles: 2

Bytes: 1

Flags: See SBC A,r8

## SBC A,n8

Subtract the value`n8`and the carry flag from

**A**.

Cycles: 2

Bytes: 2

Flags: See SBC A,r8

## SCF

Set Carry Flag.Cycles: 1

Bytes: 1

Flags:

**N**- 0
**H**- 0
**C**- 1

## SET u3,r8

Set bit`u3`in register

`r8`to 1. Bit 0 is the rightmost one, bit 7 the leftmost one.

Cycles: 2

Bytes: 2

Flags: None affected.

## SET u3,[HL]

Set bit`u3`in the byte pointed by

**HL**to 1. Bit 0 is the rightmost one, bit 7 the leftmost one.

Cycles: 4

Bytes: 2

Flags: None affected.

## SLA r8

Shift Left Arithmetic register`r8`.

Cycles: 2

Bytes: 2

Flags:

**Z**- Set if result is 0.
**N**- 0
**H**- 0
**C**- Set according to result.

## SLA [HL]

Shift Left Arithmetic byte pointed to by**HL**.

Cycles: 4

Bytes: 2

Flags: See SLA r8

## SRA r8

Shift Right Arithmetic register`r8`.

Cycles: 2

Bytes: 2

Flags:

**Z**- Set if result is 0.
**N**- 0
**H**- 0
**C**- Set according to result.

## SRA [HL]

Shift Right Arithmetic byte pointed to by**HL**.

Cycles: 4

Bytes: 2

Flags: See SRA r8

## SRL r8

Shift Right Logic register`r8`.

Cycles: 2

Bytes: 2

Flags:

**Z**- Set if result is 0.
**N**- 0
**H**- 0
**C**- Set according to result.

## SRL [HL]

Shift Right Logic byte pointed to by**HL**.

Cycles: 4

Bytes: 2

Flags: See SRA r8

## STOP

Enter CPU very low power mode. Also used to switch between double and normal speed CPU modes in GBC.Cycles: -

Bytes: 2

Flags: None affected.

## SUB A,r8

Subtract the value in`r8`from

**A**.

Cycles: 1

Bytes: 1

Flags:

**Z**- Set if result is 0.
**N**- 1
**H**- Set if borrow from bit 4.
**C**- Set if borrow (set if
`r8`>**A**).

## SUB A,[HL]

Subtract the byte pointed to by**HL**from

**A**.

Cycles: 2

Bytes: 1

Flags: See SUB A,r8

## SUB A,n8

Subtract the value`n8`from

**A**.

Cycles: 2

Bytes: 2

Flags: See SUB A,r8

## SWAP r8

Swap upper 4 bits in register`r8`and the lower 4 ones.

Cycles: 2

Bytes: 2

Flags:

**Z**- Set if result is 0.
**N**- 0
**H**- 0
**C**- 0

## SWAP [HL]

Swap upper 4 bits in the byte pointed by**HL**and the lower 4 ones.

Cycles: 4

Bytes: 2

Flags: See SWAP r8

## XOR A,r8

Bitwise XOR between the value in`r8`and

**A**.

Cycles: 1

Bytes: 1

Flags:

**Z**- Set if result is 0.
**N**- 0
**H**- 0
**C**- 0

## XOR A,[HL]

Bitwise XOR between the byte pointed to by**HL**and

**A**.

Cycles: 2

Bytes: 1

Flags: See XOR A,r8

## XOR A,n8

Bitwise XOR between the value in`n8`and

**A**.

Cycles: 2

Bytes: 2

Flags: See XOR A,r8

# SEE ALSO

rgbasm(1), rgbds(7)# HISTORY

`rgbds`

was originally written by Carsten Sørensen
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
https://github.com/gbdev/rgbds.
February 23, 2018 | Linux |