x86

问题 i have an assignment that asks to define 4 integers, each of a different byte length (1, 2, 4, 8) would this code work? segment .data one db 1 two dw 01 four dd 1011 eight dq 01101110 global _start _start: mov rax, [one] ; mov rbx, [two] ; im also curious if i can safely store these values into registers to be used for addition in the future. I'm supposed to use sign extension for the shorter values, but could use some direction 回答1: You're writing constants in decimal. If you want the digits

问题 i have an assignment that asks to define 4 integers, each of a different byte length (1, 2, 4, 8) would this code work? segment .data one db 1 two dw 01 four dd 1011 eight dq 01101110 global _start _start: mov rax, [one] ; mov rbx, [two] ; im also curious if i can safely store these values into registers to be used for addition in the future. I'm supposed to use sign extension for the shorter values, but could use some direction 回答1: You're writing constants in decimal. If you want the digits

问题 Let's say there is a piece of code: mov al, 12 mov bl, 4 sub al, bl In this case, the CF = 0 flag, but in my opinion it should be equal to 1, since the subtraction operation is implemented on an addition operation and the processor does not know what we are giving it as input, be it signed or unsigned numbers, it just does its job. That is, the code above is equivalent to the following: Enter the value 12 into the al register, i.e. 0000 1100 Enter the value 4 into the bl register, i.e. 0000

问题 Let's say there is a piece of code: mov al, 12 mov bl, 4 sub al, bl In this case, the CF = 0 flag, but in my opinion it should be equal to 1, since the subtraction operation is implemented on an addition operation and the processor does not know what we are giving it as input, be it signed or unsigned numbers, it just does its job. That is, the code above is equivalent to the following: Enter the value 12 into the al register, i.e. 0000 1100 Enter the value 4 into the bl register, i.e. 0000

问题 Let's say there is a piece of code: mov al, 12 mov bl, 4 sub al, bl In this case, the CF = 0 flag, but in my opinion it should be equal to 1, since the subtraction operation is implemented on an addition operation and the processor does not know what we are giving it as input, be it signed or unsigned numbers, it just does its job. That is, the code above is equivalent to the following: Enter the value 12 into the al register, i.e. 0000 1100 Enter the value 4 into the bl register, i.e. 0000

问题 Let's say there is a piece of code: mov al, 12 mov bl, 4 sub al, bl In this case, the CF = 0 flag, but in my opinion it should be equal to 1, since the subtraction operation is implemented on an addition operation and the processor does not know what we are giving it as input, be it signed or unsigned numbers, it just does its job. That is, the code above is equivalent to the following: Enter the value 12 into the al register, i.e. 0000 1100 Enter the value 4 into the bl register, i.e. 0000

问题 Let's say there is a piece of code: mov al, 12 mov bl, 4 sub al, bl In this case, the CF = 0 flag, but in my opinion it should be equal to 1, since the subtraction operation is implemented on an addition operation and the processor does not know what we are giving it as input, be it signed or unsigned numbers, it just does its job. That is, the code above is equivalent to the following: Enter the value 12 into the al register, i.e. 0000 1100 Enter the value 4 into the bl register, i.e. 0000

问题 Let's say there is a piece of code: mov al, 12 mov bl, 4 sub al, bl In this case, the CF = 0 flag, but in my opinion it should be equal to 1, since the subtraction operation is implemented on an addition operation and the processor does not know what we are giving it as input, be it signed or unsigned numbers, it just does its job. That is, the code above is equivalent to the following: Enter the value 12 into the al register, i.e. 0000 1100 Enter the value 4 into the bl register, i.e. 0000

问题 Suppose that CPU is running an assembly instruction, say, FOO that will be executed in several clocks (e.g. 10) An interrupt request has come just in the middle of executing FOO and processor needs to interrupt. Does it wait until command is properly executed, or is FOO aborted and will be restarted? Does it behave differently considering different types of interrupts' prioritization? 回答1: The CPU has the option of deciding to do either one, i.e. deciding when the interrupt was handled

问题 Suppose that CPU is running an assembly instruction, say, FOO that will be executed in several clocks (e.g. 10) An interrupt request has come just in the middle of executing FOO and processor needs to interrupt. Does it wait until command is properly executed, or is FOO aborted and will be restarted? Does it behave differently considering different types of interrupts' prioritization? 回答1: The CPU has the option of deciding to do either one, i.e. deciding when the interrupt was handled