63 lines
2.1 KiB
JavaScript
63 lines
2.1 KiB
JavaScript
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/*
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Utility functions to store and load coordinates to and from module memory
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Coordinates are assumed to be an array of coordinate pairs ([[x1,y1], [x2,y2], [x3,y3]])
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*/
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/**
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* Allocate memory for coordinates and stores them in a flat representation.
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* Returns a pointer to the buffer. The length of the buffer is coords.length * 2
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* @param {*} module
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* @param {Array} coords - An array of coordinate pairs
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*/
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export function storeCoords(module, coords) {
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const buffer = module._malloc(coords.length * 2 * 8)
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const heap = new Float64Array(module.HEAPF64.buffer, buffer, coords.length * 2)
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for (let i = 0; i < coords.length; i++) {
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heap[2*i] = coords[i][0]
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heap[2*i + 1] = coords[i][1]
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}
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return buffer
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}
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/**
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* Loads coordinates from the memory by the result pointer.
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* Frees the resultpointer and the result before returning
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* @param {*} module
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* @param {*} result - pointer to Uint32 array of length 2. Stores the resultPointer and resultLength
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*/
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export function loadResultAndFreeMemory(module, result) {
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const [resultPointer, resultLength] = new Uint32Array(module.HEAPU32.buffer, result, 2)
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const simplified = new Float64Array(module.HEAPF64.buffer, resultPointer, resultLength)
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const coords = unflattenCoords(simplified)
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module._free(result)
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module._free(resultPointer)
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return coords
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}
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/**
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* Loads coordinates from the memory by the result pointer without freeing memory.
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* For benchmarking purposes
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* @param {*} module
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* @param {*} result - pointer to Uint32 array of length 2. Stores the resultPointer and resultLength
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*/
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export function loadResult(module, result) {
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const [resultPointer, resultLength] = new Uint32Array(module.HEAPU32.buffer, result, 2)
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const simplified = new Float64Array(module.HEAPF64.buffer, resultPointer, resultLength)
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return unflattenCoords(simplified)
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}
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/**
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* Transforms a flat array to an array coordinate pairs
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* @param {Array} flattened - length must be even
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*/
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export function unflattenCoords (flattened) {
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const coords = []
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let x, y
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for (let i = 0; i < flattened.length; i += 2) {
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x = flattened[i]
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y = flattened[i + 1]
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coords.push([x, y])
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}
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return coords
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}
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