115 lines
3.3 KiB
C++
115 lines
3.3 KiB
C++
#ifndef INCLUDED_SWAB_H
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#define INCLUDED_SWAB_H
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/**
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* Yank in[bits[0]..bits[bits_sz]) to out[where,where+bits_sz).
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*
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* \param in A const reference to the source.
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* \param bits An array specifying the ordinals of the bits to copy.
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* \param bits_sz The size of the bits array.
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* \param out A reference to the destination.
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* \param where The offset of the first bit to write.
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*/
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template <class X, class Y>
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void yank(const X& in, const size_t bits[], size_t bits_sz, Y& out, size_t where)
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{
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for(size_t i = 0; i < bits_sz; ++i) {
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out[where+i] = in[bits[i]];
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}
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}
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/**
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* Yank back from in[where,where+bits_sz) to out[bits[0]..bits[bits_sz]).
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*
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* \param in A const reference to the source.
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* \param where The offset of the first bit to read.
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* \param out A reference to the destination.
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* \param bits An array specifying the ordinals of the bits to copy.
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* \param bits_sz The size of the bits array.
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*/
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template <class X, class Y>
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void yank_back(const X& in, size_t where, Y& out, const size_t bits[], size_t bits_sz)
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{
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for(size_t i = 0; i < bits_sz; ++i) {
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out[bits[i]] = in[where+i];
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}
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}
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/**
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* Extract a bit_vector in[begin,end) to an octet buffer.
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*
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* \param in A const reference to the source.
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* \param begin The offset of the first bit to extract (the MSB).
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* \param end The offset of the end bit.
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* \param out Address of the octet buffer to write into.
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* \return The number of octers written.
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*/
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template<class X>
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size_t extract(const X& in, int begin, int end, uint8_t *out)
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{
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const size_t out_sz = (7 + end - begin) / 8;
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std::fill(out, out + out_sz, 0);
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for(int i = begin, j = 0; i < end; ++i, ++j) {
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out[j / 8] |= (in[i] ? 1 << (7 - (j % 8)) : 0);
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}
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return out_sz;
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}
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/**
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* Extract a bit_vector in[bits[0)..bits[bits_sz)) to an octet buffer.
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*
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* \param in A const reference to the source.
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* \param bits An array specifying the ordinals of the bits to extract.
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* \param bits_sz The size of the bits array.
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* \param out Address of the octet buffer to write into.
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* \return The number of octers written.
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*/
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template<class X>
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size_t extract(const X& in, const size_t bits[], size_t bits_sz, uint8_t *out)
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{
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const size_t out_sz = (7 + bits_sz) / 8;
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std::fill(out, out + out_sz, 0);
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for(size_t i = 0; i < bits_sz; ++i) {
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out[i / 8] ^= in[bits[i]] << (7 - (i % 8));
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}
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return out_sz;
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}
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/**
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* Extract value of bits from in[bits[0..bits_sz)).
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*
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* \param in The input const_bit_vector.
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* \param begin The offset of the first bit to extract (the MSB).
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* \param end The offset of the end bit.
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* \return A uint64_t containing the value
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*/
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template<class X>
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uint64_t extract(const X& in, int begin, int end)
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{
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uint64_t x = 0LL;
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for(int i = begin; i < end; ++i) {
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x = (x << 1) | (in[i] ? 1 : 0);
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}
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return x;
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}
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/**
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* Extract value of bits from in[bits[0..bits_sz)).
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*
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* \param in A const reference to the source.
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* \param bits An array specifying the ordinals of the bits to extract.
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* \param bits_sz The size of the bits array.
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* \return A uint64_t containing the value
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*/
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template<class X>
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uint64_t extract(const X& in, const size_t bits[], size_t bits_sz)
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{
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uint64_t x = 0LL;
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for(size_t i = 0; i < bits_sz; ++i) {
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x = (x << 1) | (in[bits[i]] ? 1 : 0);
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}
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return x;
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}
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#endif // INCLUDED_SWAB_H
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