tests/test_memset_alignment.cpp

// Copyright 2017 The Emscripten Authors.  All rights reserved.
// Emscripten is available under two separate licenses, the MIT license and the
// University of Illinois/NCSA Open Source License.  Both these licenses can be
// found in the LICENSE file.

#include <memory.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <vector>
#include <iostream>
#include <algorithm>

#include <emscripten/emscripten.h>

char ptr[1024*1024*2+64] = {};

#define GUARDSIZE 32
void test_memset(int copySize, int offset)
{
	char *content = ptr + GUARDSIZE + offset;

	char *guardBefore = content - GUARDSIZE;
	char *guardAfter  = content + copySize;

	char guard = (char)rand();

	for(int i = 0; i < GUARDSIZE; ++i)
	{
		// Generate a guardband area around memory that should not change.
		guardBefore[i] = (char)(guard ^ i);
		guardAfter[i] = (char)(guard ^ i);
	}

	// Generate fill source data
	char s = (char)(rand() ^ 0xF0);

	memset(content, s, copySize);
	for(int i = 0; i < copySize; ++i)
	{
		if (content[i] != s)
		{
			printf("test_memset(copySize=%d, offset=%d failed!\n", copySize, offset);
			exit(1);
		}
	}

	// Verify guardband area
	for(int i = 0; i < GUARDSIZE; ++i)
	{
		// Generate a guardband area around memory that should not change.
		if (guardBefore[i] != (char)(guard ^ i))
		{
			printf("test_memset(copySize=%d, offset=%d failed! Pre-guardband area at i=%d overwritten!\n", copySize, offset, i);
			exit(1);
		}
		if (guardAfter[i] != (char)(guard ^ i))
		{
			printf("test_memset(copySize=%d, offset=%d failed! Post-guardband area at i=%d overwritten!\n", copySize, offset, i);
			exit(1);
		}
	}
}

void test_copysize(int copySize)
{
	for(int offset = 0; offset < 31; ++offset)
		test_memset(copySize, offset);
}

int main()
{
	srand(time(NULL));

	for(int copySize = 0; copySize < 128; ++copySize)
		test_copysize(copySize);

	for(int copySizeI = 128; copySizeI <= 1048576; copySizeI <<= 1)
		for(int copySizeJ = 1; copySizeJ <= 16; copySizeJ <<= 1)
			test_copysize(copySizeI | copySizeJ);

	printf("OK.\n");
}