Instructions

Corvassembly currently has 25 instructions, with a maximum of 32 possible given the structure of the 32-bit instruction word.

nop‎

No operation. Simply increments the program counter.

Memory Instructions

ldr <operand1>, <operand2>

Load register. Loads operand1 with operand2.

Parameters

  • operand1 – register

  • operand2 – register / immediate / variable

str <operand1>, <operand2>

Store register. Stores operand1 in operand2.

Parameters

  • operand1 – register

  • operand2 – variable

lpt <operand1>, <source>

Load from pointer. Loads operand1 from source.

Parameters

  • operand1 – register

  • operand2 – ram, rom, gpu

spt <operand1>, <source>

Store to pointer. Stores operand1 in source.

Parameters

  • operand1 – register

  • operand2 – ram, gpu

Arithmetic Instructions

cmp <operand1>, <operand2>

Compare. Compare operand1 to operand2. This instruction updates the equal, greater, and less status flags.

Parameters

  • operand1 – register

  • operand2 – register / immediate / variable

add <operand1>, <operand2>[, <result>]

Add. Adds operand2 to operand1, and stores in result. If only two arguments are given, the result is stored back in operand1. This instruction updates the zero, carry, and negative status flags.

Parameters

  • operand1 – register

  • operand2 – register / immediate / variable

  • result – register

sub <operand1>, <operand2>[, <result>]

Subtract. Subtracts operand2 from operand1, and stores in result. If only two arguments are given, the result is stored back in operand1. This instruction updates the zero, carry, and negative status flags.

Parameters

  • operand1 – register

  • operand2 – register / immediate / variable

  • result – register

mul <operand1>, <operand2>[, <result>]

Multiply. Multiplies operand1 by operand2, and stores in result. If only two arguments are given, the result is stored back in operand1. This instruction updates the zero, carry, and negative status flags.

Parameters

  • operand1 – register

  • operand2 – register / immediate / variable

  • result – register

Warning

div and mod not yet implemented in hardware!

div <operand1>, <operand2>[, <result>]

Divide. Divides operand1 by operand2, and stores in result. If only two arguments are given, the result is stored back in operand1. This instruction updates the zero, carry, and negative status flags.

Parameters

  • operand1 – register

  • operand2 – register / immediate / variable

  • result – register

mod <operand1>, <operand2>[, <result>]

Modulus. Takes the remainder of operand1 divided by operand2, and stores in result. If only two arguments are given, the result is stored back in operand1. This instruction updates the zero, carry, and negative status flags.

Parameters

  • operand1 – register

  • operand2 – register / immediate / variable

  • result – register

Logic Instructions

and <operand1>, <operand2>[, <result>]

Logical and. Performs a bitwise and operation between operand2 and operand1, and stores in result. If only two arguments are given, the result is stored back in operand1. This instruction updates the zero and negative status flags, and sets carry to zero.

Parameters

  • operand1 – register

  • operand2 – register / immediate / variable

  • result – register

or <operand1>, <operand2>[, <result>]

Logical or. Performs a bitwise or operation between operand2 and operand1, and stores in result. If only two arguments are given, the result is stored back in operand1. This instruction updates the zero and negative status flags, and sets carry to zero.

Parameters

  • operand1 – register

  • operand2 – register / immediate / variable

  • result – register

xor <operand1>, <operand2>[, <result>]

Logical exclusive or. Performs a bitwise xor operation between operand2 and operand1, and stores in result. If only two arguments are given, the result is stored back in operand1. This instruction updates the zero and negative status flags, and sets carry to zero.

Parameters

  • operand1 – register

  • operand2 – register / immediate / variable

  • result – register

not <operand1>[, <result>]

Logical not. Performs a bitwise not operation to operand1 and stores in result. If only one argument is given – assuming that argument is a register – the result is stored back in operand1. If operand1 is not a register and no valid result argument is given, the assembler reports an error. This instruction updates the zero and negative status flags, and sets carry to zero.

Parameters

  • operand1 – register / variable

  • result – register

lsl <operand1>, <operand2>[, <result>]

Logical shift left. Performs a bitshift left operation on operand1 by operand2 number of bits, and stores in result. If only two arguments are given, the result is stored back in operand1. This instruction updates the zero, carry, and negative flags.

Parameters

  • operand1 – register

  • operand2 – register / immediate / variable

  • result – register

lsr <operand1>, <operand2>[, <result>]

Logical shift right. Performs a bitshift right operation on operand1 by operand2 number of bits, and stores in result. If only two arguments are given, the result is stored back in operand1. This instruction updates the zero, carry, and negative flags.

Parameters

  • operand1 – register

  • operand2 – register / immediate / variable

  • result – register

Jump Instructions

jmp <operand1>

Jump. Jumps to the address of label operand1.

Parameters

operand1 – label

jsr <operand1>

Jump to subroutine. Pushes the current address onto the address stack and Jumps to the address of label operand1.

Parameters

operand1 – label

rts‎

Return from subroutine. Pops the last address off the address stack and Jumps to that address.

joc <condition>, <operand1>

Jump on condition. Jumps to the address of label operand1 if condition evaluates to true.

Parameters

  • condition – zero, carry, negative, equal, greater, less

  • operand1 – label

jsc <condition>, <operand1>

Jump to subroutine on condition. Pushes the current address onto the address stack and jumps to the address of label operand1 if condition evaluates to true.

Parameters

  • condition – zero, carry, negative, equal, greater, less

  • operand1 – label

rsc <condition>

Return from subroutine on condition. Pops the last address off the address stack and jumps to that address if condition evaluates to true.

Parameters

condition – zero, carry, negative, equal, greater, less

rti <interrupt>

Return from interrupt. This tells the processor to restore the register states saved when interrupt was set, pops the last address off the address stack and jumps to that address.

Parameters

interrupt – interrupt vector

ric <condition>, <interrupt>

Return from interrupt on condition. This tells the processor to restore the register states saved when interrupt was set, pops the last address off the address stack and jumps to that address if condition evaluates to true.

Parameters

  • condition – zero, carry, negative, equal, greater, less

  • interrupt – interrupt vector