The bt/bts/btr/btc instructions only deal with 16 or 32 bit operands. This is not a limitation of the instruction. After all, if you want to test bit three of the al register, you can just as easily test bit three of the ax register. On the other hand, if the index is larger than the size of . BTCSoftware - Corporation Tax UK Tax Calculators, Income Tax Calculator and Accountancy Software. This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Btc x86x86 - bt assembly instruction - Stack Overflow
Its second operand specifies the bit index into the first operand. Bt copies the addressed bit into the carry flag. For example, the instruction. This is not a limitation of the instruction. After all, if you want to test bit three of the al register, you can just as easily test bit three of the ax register. On the other hand, if the index is larger than the size of a register operand, the result is undefined. If the first operand is a memory location, the bt instruction tests the bit at the given offset in memory, regardless the value of the index.
For example, if bx contains 65 then. Once again, the size of the operand does not matter. For all intents and purposes, the memory operand is a byte and you can test any bit after that byte with an appropriate index. There are 64 bits in 8 bytes, so the 65th bit is bit one of 8 bytes past TestMe.
It doesn't copy the byte there, only the second bit in that byte to the carry flag, CF. Learn more. Asked 9 years, 3 months ago. Active 1 year, 2 months ago.
The x86 instruction set has been extended several times, introducing wider registers and datatypes as well as new functionality. Most if not all of these instructions are available in bit mode; they just operate on bit registers eax , ebx , etc.
See also x86 assembly language for a quick tutorial for this processor family. The updated instruction set is also grouped according to architecture i , i , i and more generally is referred to as x86 32 and x86 64 also known as AMD They are usable for both integer and floating point operations, see below.
MMX instructions operate on the mm registers, which are 64 bits wide. They are shared with the FPU registers. Added with Pentium MMX. Added with 6x86MX from Cyrix , deprecated now.
The following instructions can be used only on SSE registers, since by their nature they do not work on MMX registers.
Added with Xeon series and initial Core 2. Added with Core 2 manufactured in 45nm. Added with Phenom processors. Added with Nehalem processors. Introduced with the bulldozer processor core, removed again from Zen microarchitecture onward.
Supported in AMD processors starting with the Piledriver architecture and Intel starting with Haswell processors and Broadwell processors since Fused multiply-add floating-point vector multiply—accumulate with three operands. Supported in AMD processors starting with the Bulldozer architecture. Not supported by any intel chip as of Fused multiply-add with four operands.
Introduced in Intel's Xeon Phi x The x86 CPUs contain undocumented instructions which are implemented on the chips but not listed in some official documents. They can be found in various sources across the Internet, such as Ralf Brown's Interrupt List and at sandpile. In some implementations, emulated through BIOS as a halting sequence. It interacts with ICE mode. From Wikipedia, the free encyclopedia. List of x86 microprocessor instructions.
This article may be too long to read and navigate comfortably. Please consider splitting content into sub-articles, condensing it, or adding subheadings.
Please discuss this issue on the article's talk page. November Main article: AES instruction set. Main article: Intel SHA extensions.
Retrieved Archived from the original on The instruction brings down the upper word of the doubleword register without affecting its upper 16 bits. Advanced Micro Devices, Inc. Retrieved 11 December October Retrieved October 17, Assembly language Comparison of assemblers Disassembler Instruction set Low-level programming language Machine code Microassembler x86 assembly language.
Categories : X86 instructions Instruction set listings. Hidden categories: CS1 maint: BOT: original-url status unknown Articles with short description Short description is different from Wikidata Articles that may be too long from November Namespaces Article Talk. Views Read Edit View history. Help Learn to edit Community portal Recent changes Upload file.
Download as PDF Printable version. Later Intel's documentation has the generic form too. Clear interrupt flag. Used with floating-point unit. Jump if condition. Load Effective Address. Negate the operand, logical NOT. Pop data from stack. Later CPUs use 0x0F as a prefix for newer instructions. Not a real instruction.
Shift Arithmetically left signed shift left. Waits until BUSY pin is inactive used with floating-point unit. Modifies stack for entry to procedure for high level language. Takes two operands: the amount of storage to be allocated on the stack and the nesting level of the procedure. Interrupt return; D suffix means bit return, F suffix means do not generate epilogue code i.
LEAVE instruction. Usually used to change between little endian and big endian representations. Invalidate TLB Entry. Writes back all modified cache lines in the processor's internal cache to main memory and invalidates the internal caches.
Exchanges the first operand with the second operand, then loads the sum of the two values into the destination operand.