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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 ...
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 ...
bits 78–64 bit 63 bits 62–0; all 0: 0: 0: Zero. The sign bit gives the sign of the zero, which usually is meaningless. non-zero: Denormal. The value is (−1) s × m × 2 −16382 1: anything: Pseudo Denormal. The 80387 and later properly interpret this value but will not generate it. The value is (−1) s × m × 2 −16382 bits 78–64 ...
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.
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:
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
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The registers XMM8 through XMM15 are accessible only in 64-bit operating mode. SSE used only a single data type for XMM registers: four 32-bit single-precision floating-point numbers; SSE2 would later expand the usage of the XMM registers to include: two 64-bit double-precision floating-point numbers or; two 64-bit integers or; four 32-bit ...