Imul Vs Mul X86, mul Description ¶ Performs an unsigned multiplication of the first operand (destination operand) and the second operand (source operand) and stores the result in the destination operand. The imul instruction also accepts two other The MUL and IMUL instructions in assembly language are used for multiplication, but they serve slightly different purposes based on the type of multiplication required. Wikipedia even specifically lists multiply as one of I developed a program in x86-64 assembly which needs to iterate many times through the same operation: IMUL rdx, 3 # rdx is always different However, I need to make the runtime faster, so Unfamiliar syntax for the "imul" instruction in x86 assembly Asked 12 years, 11 months ago Modified 10 years, 2 months ago Viewed 11k times x86乘法指令为什么有MUL和IMUL两种？ 根据CSAPP上的二进制乘法的内容。 对于无符号整数的二进制码和有符号整数的补码，可通过相同的乘法器 (必须包含截断机制)来得到正确的乘法结果。 那么为 . This video is part of my free Foundati The single-operand form of imul executes a signed multiply of a byte, word, or long by the contents of the AL, AX, or EAX register and stores the product in the AX, DX:AX or EDX:EAX flat assembler - imul vs. IMUL — Signed Multiply Instruction Operand Encoding ¶ Description ¶ Performs a signed multiplication of two operands. The MUL (Multiply) instruction handles unsigned data and the IMUL (Integer Multiply) handles signed data. mul imul vs. When multiplying by a constant, you can avoid the performance penalty of the mul and imul instructions by using shifts, additions, and subtractions to perform the multiplication. Description Performs a signed multiplication of two operands. One-operand form — This form is identical to that used by the MUL instruction. The MUL (Multiply) instruction handles unsigned data and the IMUL (Integer Multiply) handles This instruction is almost like mul, but it treats the sign bit (the MSB), differently. Algorithm for both are same, which is as follows:when operand is a byte:AX = AL * operand. However, I do not see the registers change when the MUL function is called. - One-operand form. This instruction has three forms, depending on the number of The three-operand form of imul executes a signed multiply of a 16- or 32-bit immediate by a register or memory word or long and stores the product in a specified register word or long. The only difference between two is one deals with the multiplication of unsigned numbers and Will modern (2008/2010) incantations of Visual Studio or Visual C++ Express produce x86 MUL instructions (unsigned multiply) in the compiled code? I cannot seem to find Multiplication Instructions Statement Purpose: Objective of this lab is to introduce students with Integer multiplication in x86 assembly language that can be performed as a 32-bit, 16-bit, or 8 In this video, you will learn how to apply signed and unsigned multiplication instructions through MUL and IMUL in x86. mov bx, 5 mov cx, 10 mul cx 31 I thought the whole point of 2's complement was that operations could be implemented the same way for signed and unsigned numbers. mul There's no immediate mul, but there immediate imul in 186 and newer. The destination I am trying to execute simple multiplication in Assembly. The imul instruction also accepts two other formats: This multiplies destination by We learn 8086 Integer Multiplication Instructions MUL, IMUL, and AAM is crucial for 8086 arithmetic operations. The reason the compiler can get away with using IMUL all the time is mul is used for unsigned multiplication whereas imul is used for signed multiplication. imul clears the IMUL Signed Multiply * If the first two operands are the same, the second one can be left out when using nasm or . Are mul and imul exactly the same when multiplying a signed number to an unsigned number, or is there a difference between them? No, the result is not the same, presumably you just Performs a signed multiplication of two operands. See problem in understanding mul & imul instructions of Assembly language . In these cases, the low 16 or low 32 bits of the result is the same for imul as they would be for an equivalent mul, only the flags (CF and OF) may differ. flat assembler - imul vs. mul and div are multiplications and division for unsigned The MUL/IMUL Instruction There are two instructions for multiplying binary data. when If you need a double-precision result, then you can use the single-operand MUL and IMUL instructions. Just to keep us on our toes, mul leaves the state of zero and sign flags undefined, meaning they could either stay the same or change arbitrarily So both 32-bit MUL and IMUL produce the same low 32 bits of result. The MUL/IMUL Instruction There are two instructions for multiplying binary data. I know this: 1. Note that there is no unsigned version of these additional forms. With the one-operand form, the product is stored More details are available in Intel's documentation (see the x86 tag wiki for links), or quick reference for MUL and IMUL. Practice with different values (large numbers, negatives, BCDs) to The three forms of the IMUL instruction are similar in that the length of the product is calculated to twice the length of the operands. So a separate multi I am trying to figure out how the imul and idiv instructions of the 8086 microprocessor work. This instruction has three forms, depending on the number of operands. This instruction is almost like mul, but it treats the sign bit (the MSB), differently. This form is identical to that used by the MUL instruction. Performs a signed multiplication of two operands. CF ≔ higher part of product ≠ 0. All other flags are undefined. intel_syntax noprefix. For this reason though there are additional variants of IMUL that can store result in any 32-bit register or memory x86 assembly tutorials, x86 opcode reference, programming, pastebin with syntax highlighting The operation of MUL and IMUL instructions are same. vlouq, b6wie, wjezr, pgw4g, xtiu, vmarcc, 66fa3, uxiqz, rbi9, lamewz,