#brief description of repiola language

Introduction

Repiola is a simple virtual machine, interpreter and frontends for desktop and mobile that allows to make programs that draw on a surface.

The machine contains 8 general purpose 32 bit registers named from r0 to r7.

The r0 and r1 registers have a special purpose, they are used to determine the location where a pixel will be painted when the put instruction is executed.

since the machine executes opcodes, a language needs to be created and an interpreter/compiler to translate that language into opcodes.

The default language has a syntax very similar to ASM 80x86 and is designed to be easy to type on phones, which are the main purpose of the project.

The instructions are the following

Arithmetic instructions

• set: sets the value of a register
• set r1, 10
• set r2, r1
• add: adds a value to the value of a register, store the result on the register
• add r1, 10 # r1 = r1 + 10
• add r2, r1 # r2 = r2 + r1
• sub: substract a value to the value of a register, store the result on the register
• sub r1, 10 # r1 = r1 - 10
• sub r2, r1 # r2 = r2 - r1
• mul: multiply a value with the value of a register, store the result on the register
• mul r1, 10 # r1 = r1 `*` 10
• mul r2, r1 # r2 = r2 `*` r1
• div: divide a value with the value of a register, store the result on the register
• div r1, 10 # r1 = r1 / 10
• div r2, r1 # r2 = r2 / r1
• mod: calculate the modulo of the division, store the modulo on the register
• mod r1, 2 # r1 = r1 % 2
• mod r1, r2 # r1 = r1 % r2

Binary instructions

• and: perform the and operation between the register and a value, store the result on the register
• and r1, 8 # r1 = r1 & 8
• and r1, r2 # r1 = r1 & r2
• or: perform the or operation between the register and a value, store the result on the register
• or r1, 8 # r1 = r1 | 8
• or r1, r2 # r1 = r1 | r2
• xor: perform the xor operation between the register and a value, store the result on the register
• xor r1, 8 # r1 = r1 ^ 8
• xor r1, r2 # r1 = r1 ^ r2
• not: negate the binary value of a register, store it on the register
• not r1 # r1 = ~r1

Drawing instructions

• put: put a pixel of the color defined by the value in the position defined by r0 and r1 (x=r0, y=r1)
• put r2 # draws a pixel of the color stored in r2 in the position defined by (r0, r1)
• put 4 # draws a pixel of the color 4 in the position defined by (r0, r1)
• get: set the value of the specified register to the value of the pixel stored in (r0, r1)
• get r2 # store the color of the pixel in (r0, r1) in r2

Jump instructions

• ":": (colon) define a label at that point, labels allow to jump to that location with the jump instructions
• : foo # define a foo label
• jmp foo: inconditionally jump to foo, that means, when the instruction is reached execution continues where foo is defined
• eq: jump to a label if two values are equal
• eq r1 10 foo # jump to foo if r1 is equal to 10
• eq r1 r2 foo # jump to foo if r1 is equal to r2
• ne: jump to a label if two values are not equal
• ne r1 10 foo # jump to foo if r1 is not equal to 10
• ne r1 r2 foo # jump to foo if r1 is not equal to r2
• gt: jump to a label if the first value is greater than the second value
• gt r1 10 foo # jump to foo if r1 > 10
• gt r1 r2 foo # jump to foo if r1 > r2
• ge: jump to a label if the first value is greater or equal than the second value
• ge r1 10 foo # jump to foo if r1 >= 10
• ge r1 r2 foo # jump to foo if r1 >= r2
• lt: jump to a label if the first value is lower than the second value
• lt r1 10 foo # jump to foo if r1 < 10
• lt r1 r2 foo # jump to foo if r1 < r2
• le: jump to a label if the first value is lower or equal than the second value
• le r1 10 foo # jump to foo if r1 <= 10
• le r1 r2 foo # jump to foo if r1 <= r2

Special instructions

• rnd: generates a random number and store it on a register
• rnd r1 # generate a random number and store it on r1
• #: at the start of the line means that it's a comment, the rest of the line is not interpreted
• .: (dot) means nooperation, when read the machine does nothing for a cycle

ExamplePage