EmptyPatch.cc

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#include "EmptyPatch.hh"
#include "ranges.hh"
#include <cassert>
 
namespace openmsx {
 
void EmptyPatch::copyBlock(size_t src, std::span<uint8_t> dst) const
{
        auto size = block.size();
        if ((src + dst.size()) > size) {
                // past end
                if (size <= src) {
                        // start past size, only fill block
                        ranges::fill(dst, 0);
                } else {
                        auto part1 = size - src;
                        auto part2 = dst.size() - part1;
                        assert(dst.data() != &block[src]);
                        ranges::copy(block.subspan(src, part1), dst);
                        ranges::fill(dst.subspan(part1, part2), 0);
                }
        } else {
                if (dst.data() != &block[src]) {
                        // ranges::copy cannot handle overlapping regions, but in
                        // that case we don't need to copy at all
                        ranges::copy(block.subspan(src, dst.size()), dst);
                }
        }
}
 
} // namespace openmsx