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chsvlib
chsv helper source code
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chsvlib
chsv helper source code
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noexcept |
Performs an in-place bit-shift of a long integer specified by a vector of bytes in the Little-Endian order to the left.
| [in,out] | pValue | A pointer to a bit-shifted arbitrary precision integer, of the byte size cbValue and Little-Endian byte order. |
| cbValue | A byte size of the data pointed to by pValue. | |
| nShift | A value by which the input integer is bit-shifted to the left, that is towards the end of the buffer pValue. The value can accept every element of the domain specified by its type size_t. If the value is 0, the integer pValue is left unchanged. If the value is greater or equal to cbValue * CHAR_BIT, the resulting integer will be zero, and the corresponding buffer pValue is zeroed out by the function. |
The function performs a bit-shift of an integer specified as a byte vector in the Little-Endian order. That is, given that \(b_i\) and \(b_j\) are bytes in the vector pValue, such that \(i,j\in\mathbb{N}_0\land i < j\), byte \(b_i\) is less significant that \(b_j\). Therefore, the operation shifts the value towards the end of the buffer pValue.
For instance, given that \(B\) is a size of a byte in bits, a vector \(\left\{b_0, b_1, b_2, b_3, b_4\right\}\) representing a number \(b_4 B^4 + b_3 B^3 + b_2 B^2 + b_1 B^1 + b_0 B^0 = \overline{b_4 b_3 b_2 b_1 b_0}\), when shifted to the left by \(2B\), results in the value \(\overline{b_2 b_1 b_0 0 0} = b_2 B^4 + b_1 B^3 + b_0 B^2 + 0\cdot B^1 + 0\cdot B^0\) which is represented by the vector \(\left\{0, 0, b_0, b_1, b_2\right\}\). The bit order within a byte is not taken into account, that is platform-defined bit shift to the left is used.
The memlsh_LE_copy function can be used in order to write the result of bit-shifting to a separate buffer leaving the original integer unmodified. Use the generic version, memlsh_LE, of the function to perform the shift in possibly overlapping input and output buffers of possibly differing sizes.
1.9.1