July 2002
Intermediate to advanced
320 pages
8h 15m
English
Content preview from Hacker's Delight
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7-3. Transposing a Bit Matrix
The transpose of a matrix A is a matrix whose columns are the rows of A and whose rows are the columns of A. Here we consider the problem of computing the transpose of a bit matrix whose elements are single bits that are packed eight per byte, with rows and columns beginning on byte boundaries. This seemingly simple transformation is surprisingly costly in instructions executed.
On most machines it would be very slow to load and store individual bits, mainly due to the code that would be required to extract and (worse yet) to store individual bits. A better method is to partition the matrix into 8×8 submatrices, load each 8×8 submatrix into registers, compute the transpose of the submatrix in registers, and then ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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