High-Level Constructs Reference

This document outlines the high-level constructs for a custom assembly-like language, detailing memory management, variable declarations, expressions, control structures, and comments.

High-Level Constructs

Memory Management

• These need to go before the CODE_BEGIN section

PROG_MEMORY_START (addr in decimal)

Description: Specifies the starting address for program memory. Example: PROG_MEMORY_START 0

PROG_MEMORY_END (addr in decimal)

Description: Specifies the ending address for program memory. Example: PROG_MEMORY_END 1000

DATA_MEMORY_START (addr in decimal)

Description: Specifies the starting address for data memory. Example: DATA_MEMORY_START 1000

DATA_MEMORY_END (addr in decimal)

Description: Specifies the ending address for data memory. Example: DATA_MEMORY_END 2000

Variables

var name = initial value

• Description: Declares a variable with an initial decimal value.
• Initial Value: Must be a decimal number.
• Name Restrictions: Variable names cannot consist solely of digits.
• Value Cap: Values are limited to 2^16 bits.

Example:

var counter = 10
var maxValue = 65535

Expressions

(name) = (name or constant) (operator) (name or constant)

• Description: Assigns a result of an operation between variables or constants to a variable.
• Possible Operators: + - * /

Example:

total = value1 + value2
result = counter * 2

Control Structures

loop <amount>
{
// Instructions
}

• Description: Repeats the enclosed instructions a specified number of times.
• Amount: If the amount is -1, the loop runs indefinitely. Otherwise, it iterates based on the value in the DR register.

Example:

loop 5
{
total = total + 1
}

If Statement

if(<var_name> == <value>)
{
// Instructions
}

• Description: Executes the enclosed instructions if the specified variable equals the given value.
• Example:

if(counter == 0)
{
total = 0
}

Comments

Syntax: //COMMENT

• Description: Used to add comments to the code for documentation purposes.

Example:

// This is a comment
var temp = 5 

Example

• This example is in this repo as well (main.scc and main.samco)

main.scc

PROG_MEMORY_START 0
PROG_MEMORY_END 512

DATA_MEMORY_START 513
DATA_MEMORY_END 3840

CODE_BEGIN

var john = 150
var sam = 12
var both = 0

if sam == 24
<
john = 0
sam = 0
both = 0
>

both = 1


CODE_END

main.samco

• This is the asm produced

//var var = 150
lshf DR 0x00
lshf DR 0x96
lshf r7 0x08
lshf r7 0x81
PUT DR r7

//var var = 12
lshf DR 0x00
lshf DR 0x0c
lshf r7 0x08
lshf r7 0x82
PUT DR r7

//var var = 0
lshf DR 0x00
lshf DR 0x00
lshf r7 0x08
lshf r7 0x83
PUT DR r7


//If statement begins
lshf r1 0x21
lshf r1 0x77
get r2 r1
lshf r1 0x00
lshf r1 0x0c
lshf r3 0x00
lshf r3 0x28
sub r2 r1
JZ r3

//john = 0
lshf DR 0x00
lshf DR 0x00
lshf r6 0x21
lshf r6 0x76
put DR r6

//sam = 0
lshf DR 0x00
lshf DR 0x00
lshf r6 0x21
lshf r6 0x77
put DR r6

//both = 0
lshf DR 0x00
lshf DR 0x00
lshf r6 0x21
lshf r6 0x78
put DR r6

//both = 1
lshf DR 0x00
lshf DR 0x01
lshf r6 0x21
lshf r6 0x78
put DR r6