RISC-V Assembly

Write and run RISC-V assembly in the browser. Start with a single instruction and work up to functions and memory. The assembler and simulator both run in the browser.

Learn more Awesome RISC-V list

Lessons

What is assembly?Registers Doing math Input & output Decisions & loops Functions & the stack Memory: load & store Vectors: indexing by position Matrices: two indices, one address

Countries

Brazil

Is Brazil producing chips? Brazil designs chips, from the RISC-V microcontroller BlueMacaw to research cores such as NoX, while domestic fabrication depends on foreign foundries. The state-owned fab CEITEC was dissolved by decree in 2020.

Read the entry Country

Ukraine

Does Ukraine produce chips? Ukraine has no chip factory. The country is building a fabless industry that designs chips at home and has them manufactured abroad, on top of Europe's largest titanium reserves.

Reference

Arithmetic

Add two registers together.

Subtract one register from another.

Add a small constant to a register.

Multiply, keeping the low 32 bits.

High 32 bits of a signed product.

Signed integer division.

Unsigned integer division.

Signed remainder (modulo).

Unsigned remainder.

Flip the sign of a number.

Bitwise logic

Bitwise AND of two registers.

Bitwise OR of two registers.

Bitwise exclusive-OR.

AND with a constant.

OR with a constant.

XOR with a constant.

Flip every bit.

Shifts

Shift bits left (by a register).

Shift bits right, zero-filled.

Shift right, keeping the sign.

Shift left by a fixed amount.

Shift right by a constant, zero-filled.

Shift right by a constant, sign-kept.

Compare & set

Set to 1 if less than (signed).

Set if less than (unsigned).

Set if less than a constant (signed).

Set if less than a constant (unsigned).

Set to 1 if the value is zero.

Set to 1 if the value is non-zero.

Memory

Load a 32-bit word from memory.

Load a 16-bit halfword (signed).

Load one byte (signed).

Load a 16-bit halfword (unsigned).

Load one byte (unsigned).

Store a 32-bit word to memory.

Store the low 16 bits.

Store the low 8 bits.

Load the address of a label.

Load any constant into a register.

Copy one register to another.

Branches

Jump if two registers are equal.

Jump if two registers differ.

Jump if less than (signed).

Jump if greater or equal (signed).

Jump if less than (unsigned).

Jump if greater or equal (unsigned).

Jump if the register is zero.

Jump if the register is non-zero.

Jump if the register is negative.

Jump when the register holds zero or a positive value.

Jump if the register is positive.

Jump when the register holds zero or a negative value.

Jump if greater than (signed).

Jump if less or equal (signed).

Jumps & functions

Call: jump and save the return spot.

Jump to a computed address, and link.

Jump unconditionally.

Jump to an address in a register.

Call a function.

Return from a function.

Load a constant into the upper bits.

Add an upper constant to the PC.

System

Ask the system to do something.

Do nothing for one instruction.

Stop the program at a breakpoint.

Return from a trap handler.

Wait until an interrupt arrives.

Exchange the contents of a register with a control register.

Read a control register and set selected bits in it.

Read a control register and clear bits in it.

Write a constant into a control register and read the old value.

Read a control register and set bits from a constant.

Read a control register and clear bits from a constant.

Read a control register.

Write a register into a control register.

Set bits in a control register.

Clear bits in a control register.

Write a constant into a control register.

Set bits in a control register from a constant.

Clear bits in a control register from a constant.