Function buildCallerFunction

src/em/Caller.ts:119–174

Dynamically build a function that calls an Asm.js invoker * with appropriate type conversion for complicated types: * - Push arguments to stack. * - Read return value. * - Restore stack pointer if necessary.

(
		dynCall: Func,
		ptrType: _class.BindClassPtr | null,
		ptr: number,
		num: number,
		policyTbl: PolicyTbl | null,
		needsWireWrite: boolean,
		prefix: string,
		returnType: BindType,
		argTypeList: BindType[],
		mask?: number,
		err?: () => void
	)

		* - Restore stack pointer if necessary. */

	function buildCallerFunction(
		dynCall: Func,
		ptrType: _class.BindClassPtr | null,
		ptr: number,
		num: number,
		policyTbl: PolicyTbl | null,
		needsWireWrite: boolean,
		prefix: string,
		returnType: BindType,
		argTypeList: BindType[],
		mask?: number,
		err?: () => void
	) {
		const argList = makeArgList(argTypeList.length);
		/** List of arbitrary data for type converters.
		  * Each one may read and write its own slot. */
		const convertParamList: any[] = [];

		// Build code for function call and type conversion.

		const callExpression = makeWireRead(
			convertParamList,
			policyTbl,
			returnType,
			'dynCall(' +
				[prefix].concat(argList.map(
					// TODO: if one wireWrite throws,
					// resources allocated by others may leak!
					(name: string, index: number) => makeWireWrite(
						convertParamList,
						policyTbl,
						argTypeList[index],
						name
					)
				)).join(',') +
			')'
		);

		// Build code to allocate and free the stack etc. if necessary.

		const resourceSet = listResources([returnType], argTypeList);

		const sourceCode = (
			'function(' + argList.join(',') + '){' +
				(mask ? 'this.__nbindFlags&mask&&err();' : '') +
				resourceSet.makeOpen() +
				'var r=' + callExpression + ';' +
				resourceSet.makeClose() +
				'return r;' +
			'}'
		);

		// Use eval to allow JIT compiling the function.

		return(eval('(' + sourceCode + ')') as (...args: any[]) => any);
	}

	/** Dynamically build a function that calls a JavaScript callback invoker