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copied!<p>Regarding doing this in Java:</p> <p>Your loop</p> <pre><code>for(int i = 0 ; i < SourceDataSize ; i ++ ) { Destination[i] = SourceData[i + 0x100]; } </code></pre> <p>will always start copying data from <code>0x100</code> elements into SourceData; this may not be desired behavior. (For instance, when <code>i=0</code>, <code>Destination[0] = SourceData[0 + 0x100];</code> and so forth.) This would be what you wanted if you never wanted to copy <code>SourceData[0]..SourceData[0xFF]</code>, but note that hard-coding this prevents it from being a drop-in replacement for memcpy.</p> <p>The reason the <code>intSize</code> value is specified in the original code is likely because the first <code>intSize</code> elements are not part of the 'actual' data, and those bytes are used for bookkeeping somehow (like a record of what the total size of the buffer is). <code>memcpy</code> itself doesn't 'see' the offset; it only knows the pointer it's starting with. <code>SourceData + intSize</code> creates a pointer that points <code>intSize</code> bytes past <code>SourceData</code>.</p> <p>But, <strong>more importantly</strong>, what you are doing is likely to be <strong>extremely slow</strong>. <code>memcpy</code> is a <em>very</em> heavily optimized function that maps to carefully tuned assembly on most architectures, and replacing it with a simple loop-per-byte iteration will dramatically impact the performance characteristics of the code. While what you are doing is <strong>appropriate if you are trying to understand how memcpy and pointers work</strong>, note that if you are attempting to port existing code to Java for actual use you will likely want to use a morally equivalent Java function like <code>java.util.Arrays.copyOf</code>.</p>

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