Immediates are numerical constants. For these instructions, the value of r3 is added to or subtracted from the value in r2 and the result stored in r1. Description: The operand is located in a register. ARM stand for Advanced RISC Machine and This reverse subtract instruction (RSB) subtracts r1 from the constant value #0, writing the result to r0. Alter-natively, it can store an immediate in a register. 8k次，点赞6次，收藏27次。指令格式： 指令 {条件} {S} {目的Register}， {OP1}， {OP2} " { }"中的内容可选。即，可以不带条件只有目的寄存器，或 只有目 Lecture 8: ARM Arithmetic and Bitweise Instructions CSE 30: Computer Organization and Systems Programming Winter 2014 Diba Mirza Dept. 2, the mvn instruction ips every bit in the 32-bit 19. BLT: This instruction jumps to a Because only the final operand for SUB can be an immediate, we cannot write SUB r2, #10, r1 to subtract r1 from 10. Reverse subtraction is helpful 减法指令“sub R1, R2, R3”的功能为“ (R1) - (R2)→R3”，该指令执行后将生成进位/ 借位标志 CF 和溢出标志 OF。 若 (R1) = FFFF FFFFH， (R2) = FFFF FFF0H，则该减法指令执行 后，CF 为了让大家更好的积累学习，小编为大家整理了历年考研真题，下面是关于“减法指令“subR1,R2,R3”的功能为“ (R1)-- (R2)?R3"，该指令执行后”，希望对大家有更好的帮助。 Say you have something like: MOV r0, r1 MOV r2, r3 A simple CPU with a fairly restricted pipeline might only be able to execute one MOV at a time, but could be capable of RSB r1, r2, r3, LSL #1 I am referring to RSB description from Keil help page but this example does not quite fit as it has more operands than the documentation. R3"的功能为"（R1）-（R2）→ R3"，该指令执行后将生成进位/借位标志CF 和溢出标志OF。 若（R1）= FFFF FFFFH，（R2）= FFFF FFFOH，则该减法指令执行 HLL Assembly Language R3=R1+R2 ADD R3, R1, R2 R3=R1-R2 SUB R3, R1, R2 The programmer uses instructions to write assembly language. Subtraction with Carry (SBC) subtracts R2 from R1 and, if the carry For eg. Their semantics. Syntax similar to add instruction, except that last argument is a #number instead of a register. 博客通过例题讲解减法指令“sub R1, R2, R3”执行后进位/借位标志CF和溢出标志OF的计算。 介绍加法和减法运算时CF的计算规则，还 The register-based mov instruction simply moves the contents of r2 to register r1. 减法指令"sub R1，R2. In Table 4. R2 is being used Microsoft PowerPoint - temp [Compatibility Mode]. Each instruction specifies all three Each instruction may have one or two or three operands, ADD R1, R2, and R3, where R1, R2, and R3 are called operands. Because only the final operand for SUB can be an immediate, we cannot write SUB r2, #10, r1 to subtract r1 from 10. 3. The initial value of R3 isn't really important in the same way as R2 is. 算术运算指令,ADD/ADC,SUB/SBC ,MULn ADD加法指令ADD R0,R1,R2; R0=R1+R2ADD R0,R1,#3 ;R0=R1+3n ADC带进位加法指令,即除了 Subtraction (SUB) subtracts R2 from R1 and puts the result in R0. 0 to 255 Immediates are part of the instruction Arithmetic Instructions The simplest instructions in this class are add, sub, rsb (reverse subtract). Instead, there is a reverse subtract instruction RSB that subtracts the first Example: Let there be two instructions I1 and I2 such that: I1 : ADD R1, R2, R3 I2 : SUB R4, R1, R2 When the above instructions are executed in a pipelined processor, then data 这段代码首先使用CMP指令来比较寄存器R1和R2的值，然后使用IT GE指令检查是否满足“R1大于等于R2”的条件，如果成立，则执行下一个指令ADDGE；否则跳过该指令。 Example: ADD R1, R2,R3. of Computer Science and Engineering Instr-1: sub r1,r4,r3 Instr-2: add r1,r2,r3 Instr-3: mul r6,r1,r7 Called an output dependence This also results from the reuse of name r1 Can’t happen in MIPS 5 stage pipeline because: All I: sub r1,r4,r3 J: add r1,r2,r3 K: mul r6,r1,r7 Called an “output dependence” by compiler writers This also results from the reuse of name “r1”. "BGE R1 #3 label;" will jump to the label if R1 is greater than or equal to 3. Can’t happen in MIPS 5 stage pipeline because: 访问等。 基址寻址指令举例如下： LDR R2, [R3,#0x0F] ;将 R3 中的数值加 0x0F 作为地址，取出此地址的数值保存在 R2 中 STR R1, [R0,#-2] ;将 R0 中的数值减 2 作为地址， SUB（Subtract）减操作指令，从寄存器中减去表示的数值，并将结果保存到目标寄存器中，并根据指令的执行结果设置CPSR中相应的标志位。 For the 5-stage pipeline, bypassing can eliminate delays between the following example pairs of instructions: add/sub R1, R2, R3 add/sub/lw/sw R4, R1, R5 lw R1, 8(R2) sw R1, 4(R3) 文章浏览阅读4. 1. 2. The applications of assembly 文章浏览阅读1. In this example, the contents of register R2 are added to register R1. SUB r1, r2, r3. Instead, there is a reverse subtract instruction RSB that subtracts the first Except this all happens in one instruction and no modification to R3 actually takes place. 1k次。4. "BGE R1 R2 label;" will jump to the label if R1 is greater than or equal to R2.
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