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Given a 6-bit input, the 4-bit output is found by selecting the row using the outer two bits, and the column using the inner four bits. For example, an input " 0 1101 1 " has outer bits " 01 " and inner bits "1101"; noting that the first row is "00" and the first column is "0000", the corresponding output for S-box S 5 would be "1001" (=9), the ...
AMD64 (also variously referred to by AMD in their literature and documentation as “AMD 64-bit Technology” and “AMD x86-64 Architecture”) was created as an alternative to the radically different IA-64 architecture designed by Intel and Hewlett-Packard, which was backward-incompatible with IA-32, the 32-bit version of the x86 architecture.
ICE is a 16-round Feistel network.Each round uses a 32→32 bit F function, which uses 60 bits of key material. The structure of the F function is somewhat similar to DES: The input is expanded by taking overlapping fields, the expanded input is XORed with a key, and the result is fed to a number of reducing S-boxes which undo the expansion.
While what these instructions do is similar to bit level gather-scatter SIMD instructions, PDEP and PEXT instructions (like the rest of the BMI instruction sets) operate on general-purpose registers. [12] The instructions are available in 32-bit and 64-bit versions. An example using arbitrary source and selector in 32-bit mode is:
4-level paging of the 64-bit mode. In the 4-level paging scheme (previously known as IA-32e paging), the 64-bit virtual memory address is divided into five parts. The lowest 12 bits contain the offset within the 4 KiB memory page, and the following 36 bits are evenly divided between the four 9 bit descriptors, each linking to a 64-bit page table entry in a 512-entry page table for each of the ...
With the 52 bits of the fraction (F) significand appearing in the memory format, the total precision is therefore 53 bits (approximately 16 decimal digits, 53 log 10 (2) ≈ 15.955). The bits are laid out as follows: The real value assumed by a given 64-bit double-precision datum with a given biased exponent and a 52-bit fraction is
An example of a 64-bit "expansion" P-box which spreads the input S-boxes to as many output S-boxes as possible. In block ciphers based on substitution-permutation network , the P-boxes, together with the "substitution" S-boxes are used to make the relation between the plaintext and the ciphertext difficult to understand (see Shannon's Confusion ...
Thus, from 64 bits in the page table entry, 12 low-order and 12 high-order bits have other uses, leaving 40 bits (bits 12 though 51) for the physical page number. Combined with 12 bits of "offset within page" from the linear address, a maximum of 52 bits are available to address physical memory.