ECS50-L14

📗 -> 11/18/24: ECS50-L14

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🎤 Vocab

❗ Unit and Larger Context

Small summary

✒️ -> Scratch Notes

Syntax For Inline

• Read inputs section first
• Inline will save registers you “tell them about” and restore them after execution
  • Could mess things up if you don’t tell it about it and use it anyway
• Does not follow GCC calling conventions
• +a (a)
  • Applied in output section
  • Before runs a will go to EAX (a -> EAX)
  • EAX will be copied to a (EAX -> a)
• can use “r” to refer to any register
  • “+r” (a), “=r” (temp)
    • // a -> random register, random register -> a on output
    • // random register -> temp
• m - Memory
• g - General?
• “Compiler assumes that you will not write to outputs before you are done using all of your inputs”
• [b] "m" (b) - m makes b be stored in memory

__asm__(
assembly code :
outputs :
inputs : 
clobbered 
);
// outputs,inputs, and clobbered are all optional

int abcAdd(int a, int b) {
	int result;
	__asm__(
	"movl eax;"
	"addl eax;"
	"movl $12, %%edx;" :
	"=a (result)" : // = sign means that result will be overwritten
	// After code runs, copy EAX into result
	// =S (result) would mean copy ESI into result
	"b" (b), "c" (a) : // b -> EBX and c -> ECX
	"cc", "%edi" // This tells it things to modify
	// modify "cc" flags
	// modify "edi"
	)
}

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