ISA

Instructions Format

The nu+ instructions have a fixed length of 32 bits. They are grouped in seven types:

• The R type includes the logical and arithmetic operations and memory operations.

• The I type includes the logical and arithmetic operations between a register operand and an immediate operand.

• The MOVEI type includes the load operations of an immediate operand in a register.

• The C type used for control operations and for synchronization instructions.

• The JR type includes jump instructions.

• The M type includes the instructions used to access memory.

• The M-poly type is used for memory instructions which uses a polyhedral access pattern.

R type instructions

• RR (Register to Register) has a destination register and two source registers.
• RI (Register Immediate) has a destination register and one source registers and an immediate encoded in the instruction word.

Mnemonic	Opcode	Meaning	Operation
or	1	or	Rb
and	2	and	Rd = Ra & Rb
xor	3	xor	Rd = Ra ^ Rb
add	4	addition	Rd = Ra + Rb
sub	5	subtraction	Rd = Ra – Rb
mull	6	multiplication	Rd = Ra * Rb
mulh	7	high multiply	Rd = Ra * Rb
mulhu	8	high multiply unsigned	Rd = Ra * Rb
ashr	9	arithmetic shift right	Rd = Ra ‘>> Rb
shr	10	shift right	Rd = Ra >> Rb
shl	11	shift left	Rd = Ra << Rb
clz	12	count leading zeros
ctz	13	count trailing zeros
shuffle	24	vector shuffle	Rd[i] = Ra[Rb[i]]
getlane	25	Get lane from vector	Rd = Ra[Rb]
move	32	move register	Rd = Ra
add_f	33	floating point add	Rd = Ra + Rb
sub_f	34	floating point sub	Rd = Ra – Rb
mul_f	35	floating point multiplication	Rd = Ra * Rb
div_f	36	floating point division	Rd = Ra / Rb
sext8	43	sign extend 8 bits
sext16	44	sign extend 16 bits
sext32	45	sign extend 32 bits
f32tof64	46	cast float to double
f64tof32	47	cast double to float
i32tof32	48	cast integer to float
f32toi32	49	cast float to integer

MOVEI type instructions

MVI (Move Immediate) has a destination register and a 16 bit instruction encoded immediate.

M type instructions

MEM (Memory Instruction) has a destination/source field, in case of load the first register asses the destination register, otherwise in case of store the first register contains the store value. Next in both cases there is the base address and the immediate. The sum of base address and immediate will give the effective memory address.