Instruction List

Below is a list of all functions defined by default for the ICMC processor assembly language. For each instruction, there is:

• an explanation of its functionality or an explanatory pseudo-code, the latter in notation similar to that found in the C programming language.

• the specification of the instruction format in binary code. The following conventions are assumed:

  • x: bit whose value for the instruction in question is not significant;
  • |: separation between instruction fields;
  • c: "carry"
  • > end: a 16-bit memory address, described on the line following the instruction;
  • > num: a 16-bit positive integer value, described on the line following the instruction.

Data Manipulation Instructions

Memory Access

Instructions for writing (store) to and reading (load) from memory.

Mnemonic	Pseudo-code	Instruction format
store label, rx	*label = rx	110001 | rx | xxxxxxx | > end
storei rx, ry	**rx = ry	111101 | rx | ry | xxxx
load rx, label	rx = *label	110000 | rx | xxxxxxx | > end
loadi rx, ry	rx = **ry	111100 | rx | ry | xxxx
loadn rx, #num	rx = num	111000 | rx | xxxxxxx | > num

Movement between Registers

Copies the value of one register to another.

Mnemonic	Pseudo-code	Instruction Format
mov rx, ry	rx = ry	110011 | rx | ry | xxx0
mov rx, sp	rx = sp	110011 | rx | xxxxx01
mov sp, rx	sp = rx	110011 | rx | xxxxx11

Arithmetic Operations

Mnemonic	Pseudo-code	Instruction Format
add rx, ry, rz	rx = ry + rz	100000 | rx | ry | rz | 0
addc rx, ry, rz	rx = ry + rz + carry	100000 | rx | ry | rz | 1
sub rx, ry, rz	rx = ry - rz	100001 | rx | ry | rz | 0
subc rx, ry, rz	rx = ry - rz + carry	100001 | rx | ry | rz | 1
mul rx, ry, rz	rx = ry × ry	100010 | rx | ry | rz | 0
mulc rx, ry, rz	rx = ry × ry + carry	100010 | rx | ry | rz | 1
div rx, ry, rz	rx = ry ÷ ry	100011 | rx | ry | rz | 0
divc rx, ry, rz	rx = ry ÷ ry + carry	100011 | rx | ry | rz | 1
mod rx, ry, rz	rx = ry % ry	100101 | rx | ry | rz | 0
modc rx, ry, rz	rx = ry % ry + carry	100101 | rx | ry | rz | 1
inc rx	rx + 1	100100 | rx | 0 | xxxxxx
dec rx	rx - 1	100100 | rx | 1 | xxxxxx

info

When an arithmetic operation results in zero or a negative number, the fr register assumes a value corresponding to these results.

Logical Operations

Mnemonic	Pseudo-code	Instruction Format
and rx, ry, rz	rx = ry & rz	010010 | rx | ry | rz | x
or rx, ry, rz	rx = ry | rz	010011 | rx | ry | rz | x
xor rx, ry, rz	rx = ry ^ rz	010100 | rx | ry | rz | x
not rx, ry	rx = ~ry	010101 | rx | ry | xxxx

Bit Movement

Commands that manipulate the values stored in registers in their binary form.

rotl

Mnemonic	Instruction Format
rotl rx, #num	010000 | rx | 10x | num

Moves all bits num digits to the left, and the num most significant digits are "rotated" to become the num least significant digits.

rotr

Mnemonic	Instruction Format
rotr rx, #num	010000 | rx | 11x | num

Moves all bits num digits to the right, and the num least significant digits become the num most significant digits.

shiftl0

Mnemonic	Instruction Format
shiftl0 rx, #num	010000 | rx | 000 | num

Move all bits num digits to the left, and fills the num least significant bits with 0.

shiftl1

Mnemonic	Instruction Format
shiftl1 rx, #num	010000 | rx | 001 | num

Move all bits num digits to the left, and fills the num least significant bits with 1.

shiftr0

Mnemonic	Instruction Format
shiftr0 rx, #num	010000 | rx | 010 | num

Move all bits num digits to the right, and fills the num most significant bits with 0.

shiftr1

Mnemonic	Instruction Format
shiftr1 rx, #num	010000 | rx | 011 | num

Move all bits num digits to the right, and fills the num most significant bits with 1.

info

In all bit movement instructions, num is a 4-bit positive integer.

Input/Output

Input

Mnemonic	Instruction Format
inchar rx	110101 | rx | xxxxxxx

Stores in rx a value corresponding to a key pressed at the moment the instruction is read.

info

The value stored when no key is pressed is 255.

Output

Mnemonic	Instruction Format
outchar rx, ry	110010 | rx | xxxx

Prints on the screen at index ry the character at index rx.

Stack

Stores (push) or removes (pop) data from the stack.

Mnemonic	Instruction Format
push rx	000101 | rx | 0 | xxxxxx
push fr	000101 | xxx | 1 | xxxxxx
pop rx	000110 | rx | 0 | xxxxxx
push fr	000110 | xxx | 1 | xxxxxx

Comparison

Mnemonic	Instruction Format
cmp rx, ry	010110 | rx | ry | xxxx

Depending on the result of the comparison between the values stored in rx and ry, the fr register assumes a value to indicate if rx is equal, greater, or less than ry.

Jump

If the condition is met in fr, then pc = *label

Mnemonic	Condition	Instruction Format
jmp label	Unconditional	000010 | 0000 | xxxxxx
jeq label	EQual	000010 | 0001 | xxxxxx
jne label	Not Equal	000010 | 0010 | xxxxxx
jz label	Zero	000010 | 0011 | xxxxxx
jnz label	Not Zero	000010 | 0100 | xxxxxx
jc label	Carry	000010 | 0101 | xxxxxx
jnc label	No Carry	000010 | 0110 | xxxxxx
jgr label	GReater than	000010 | 0110 | xxxxxx
jle label	LEsser than	000010 | 1000 | xxxxxx
jeg label	Equal or Greater	000010 | 1001 | xxxxxx
jel label	Equal or Lesser	000010 | 1010 | xxxxxx
jov label	OVerflow	000010 | 1011 | xxxxxx
jnov label	No OVerflow	000010 | 1100 | xxxxxx
jn label	Negative	000010 | 1101 | xxxxxx
jdz label	Division by Zero	000010 | 1110 | xxxxxx

Call

If the condition is met in fr, then execute the following instructions:

push pc
jmp label

Mnemonic	Condition	Instruction Format
call label	Unconditional	000011 | 0000 | xxxxxx
ceq label	EQual	000011 | 0001 | xxxxxx
cne label	Not Equal	000011 | 0010 | xxxxxx
cz label	Zero	000011 | 0011 | xxxxxx
cnz label	Not Zero	000011 | 0100 | xxxxxx
cc label	Carry	000011 | 0101 | xxxxxx
cnc label	No Carry	000011 | 0110 | xxxxxx
cgr label	GReater than	000011 | 0110 | xxxxxx
cle label	LEsser than	000011 | 1000 | xxxxxx
ceg label	Equal or Greater	000011 | 1001 | xxxxxx
cel label	Equal or Lesser	000011 | 1010 | xxxxxx
cov label	OVerflow	000011 | 1011 | xxxxxx
cnov label	No OVerflow	000011 | 1100 | xxxxxx
cn label	Negative	000011 | 1101 | xxxxxx
cdz label	Division by Zero	000011 | 1110 | xxxxxx

Return

Complementing the call instruction, this performs:

loadi pc, sp
inc sp
inc pc

Mnemonic	Instruction Format
rts	000100 | xxxx | x | xxxxx

Control

Mnemonic	Action	Instruction Format
clearc	c = 0	001000 | 0 | xxxxxxxxx
setc	c = 1	001000 | 1 | xxxxxxxxx
halt	Stop program execution	001111 | xxxxxxxxxx
nop	No operation	000000 | xxxxxxxxxx
breakp	Insert breakpoint	001110 | xxxxxxxxxx