instruction-set

问题 I want to understand the importance of Q flag in ARM Processor. I know there are certain instructions like QADD,QSUB etc. But I need to understand this with some examples which will clarify the concept. Please explain me. Thank you 回答1: This is explained in the "ARM Architecture Reference Manual" (ARM DDI 0100E): Bit[27] of the CPSR is a sticky overflow flag, also known as the Q flag. This flag is set to 1 if any of the following occurs: Saturation of the addition result in a QADD or QDADD

问题 I want to understand the importance of Q flag in ARM Processor. I know there are certain instructions like QADD,QSUB etc. But I need to understand this with some examples which will clarify the concept. Please explain me. Thank you 回答1: This is explained in the "ARM Architecture Reference Manual" (ARM DDI 0100E): Bit[27] of the CPSR is a sticky overflow flag, also known as the Q flag. This flag is set to 1 if any of the following occurs: Saturation of the addition result in a QADD or QDADD

问题 This my assembly code. a EQU 0x20000000 b EQU 0x20000004 c EQU 0x20000008 LDR R4, =a LDR R0, [R4] LDR R4, =b LDR R1, [R4] LDR R4, =c I had two questions. what after LDR R0, [R4] what goes inside R[4] ? 0x20000000 or contents of the memory at 0x20000000 ? And second, after the last line, what goes inside R4 ? c or contents of memory at 0x20000008 ? I've searched the internet about EQU and LDR, my own guess is that to all to questions, it goes the contents of the memory, but I'm confused

问题 I’ve been told that lea %rax, %rdx is invalid syntax as the source needs to be in brackets, i.e lea (%rax), %rdx I think I’ve clearly misunderstood both lea and the purpose of brackets. I thought that lea %rax, %rdx would move the memory address stored in %rax, to %rdx, but apparently this is what lea (%rax), %rdx does? What confuses me is that I thought brackets signify going to an address in memory, and taking the value at that address. So by using brackets lea would be moving a value from

问题 I was wondering if instruction set and assembly language are the same thing? If not, how do they differ and what are their relations? Thanks and regards! 回答1: I think everyone is giving you the same answer. Instruction set is is the set (as in math) of all instructions the processor can execute or understand. Assembly language is a programming language. Let me try some examples based on some of the questions you are asking. And I am going to be jumping around from processor to processor with

问题 I was wondering if instruction set and assembly language are the same thing? If not, how do they differ and what are their relations? Thanks and regards! 回答1: I think everyone is giving you the same answer. Instruction set is is the set (as in math) of all instructions the processor can execute or understand. Assembly language is a programming language. Let me try some examples based on some of the questions you are asking. And I am going to be jumping around from processor to processor with

来源： https://stackoverflow.com/questions/19656586/what-do-we-mean-by-instruction-size

来源： https://stackoverflow.com/questions/40685938/differentiate-data-from-instructions-in-arm

来源： https://stackoverflow.com/questions/40685938/differentiate-data-from-instructions-in-arm

来源： https://stackoverflow.com/questions/40685938/differentiate-data-from-instructions-in-arm