任何人都可以向我解釋這個簡短的程序是幹什麼的?瞭解ARM彙編代碼
ORIGIN 0x1000
one DEFW 13
two DEFW 29
three DEFW 0
ORIGIN 0x1010
ENTRY
ADR R0, one
LDR R1, [R0]
LDR R2, [R0, #4]
ADD R1, R2, R1
STR R1, [R0, #8]
SWI 2
如果我想正確的,它增加了「一」到「二」,並將結果在「三」。我對麼?
任何人都可以向我解釋這個簡短的程序是幹什麼的?瞭解ARM彙編代碼
ORIGIN 0x1000
one DEFW 13
two DEFW 29
three DEFW 0
ORIGIN 0x1010
ENTRY
ADR R0, one
LDR R1, [R0]
LDR R2, [R0, #4]
ADD R1, R2, R1
STR R1, [R0, #8]
SWI 2
如果我想正確的,它增加了「一」到「二」,並將結果在「三」。我對麼?
是的。
ORIGIN 0x1000 # Start at address 0x1000
one DEFW 13 # Allocate 4-bytes of space for a variable called one and set it to 13
two DEFW 29 # Allocate 4-bytes of space for a variable called two and set it to 29
three DEFW 0 # Allocate 4-bytes of space for a variable called three and set it to 0
ORIGIN 0x1010 # Skip ahead to address 0x1010 (this really leaves a 4-byte gap)
ENTRY # Mark next instruction as the begining of program
ADR R0, one # Load address of one into R0
LDR R1, [R0] # Load contents of one (pointed to but R0) into R1
LDR R2, [R0, #4] # Load contents of two (pointed to but R0 + 4) into R2
ADD R1, R2, R1 # R1 = R2 + R1
STR R1, [R0, #8] # Store R1 into three (pointed to but R0 + 8)
SWI 2 # Execute a software interrupt
或
three = one + two
不知道的 'SWI 2' 這可能是特定於平臺的東西。也許只是程序調用的通用結束。
+1:http://www.ee.ic.ac.uk/pcheung/teaching/ee2_computing/swi.pdf似乎暗示「SWI 2」會打印到某種調試流(至少在該系統上) 。 – Leo
在某些ARM系統上,SWI代表「軟件中斷」。 –
SWI是軟件中斷指令。正如@Pete Fordham所說,SWI 2取決於平臺。 –
+1爲真棒圖標! –
這是功課嗎?你爲什麼混淆它?如果你這樣做對別人沒用。 – tangrs