types

AssemblyScript WASM - Add Numbers

This example package demonstrates compiling a simple AssemblyScript program, types.ts which adds two numbers to WASM, executing it in a host environment, and accessing it's methods.

Installing Dependencies

from the add directory project root:

npm install

Compiling AssemblyScript to WASM

To compile the types.ts code to a WASM binary:

npm run build

A types.wasm file will be produced in the build directory

Testing

Test the module outside of the context of the blockchain:

npm test

This will run NodeJS based tests in the test directory. For example in types.unit.spec.js test instantiation of the compiled WASM module, and assertions to verify its API and behavior:

describe('Strings', function () {
        it('Get String', function () {

            //use the __getString AssemblyScript wrapper to get the value from the pointer returned
            const pointer = module.getString();
            const string = module.__getString(pointer);

            //release the result pointer
            module.__release(pointer);

            assert.strictEqual(string, "It's Alive!!!");
        });
    
    ...
    });

API

add(i32 x, i32 y) - i32

Add two integers, return the result

getFloat() - f64

Return the double representation of 1.001

addFloats(f64 x, f64 y) - f64

Returns the float result of adding two floating point numbers together

getTrue() - i32

Return the integer representation of true (1)

getFalse() - i32

Return the integer representation of false (0)

echoBoolean(i32 x) - i32

Return the integer representation of i32 x

negate(boolean x) - i32

Return the boolean negation of integer representation of boolean x

or(boolean x, boolean y) - i32

Return the integer representation of boolean x or'd with boolean y

getString() - i32

Returns a pointer in memory to a string "It's Alive!!!"

getExcitingString(string(i32) x) - string(i32)

Appends an exclamation point on the end of string pointer x

concat(string(i32) x, string(i32) y) - string(i32)

Appends string pointer x to string pointer y and returns a pointer to the result

getIntArray() - array(i32)

Returns a pointer in memory the integer array [1, 1, 3, 5, 8]

getLength(array(i32) x) - i32

Returns the length of the array at pointer x