Parameter passing in registers in ARM Architecture - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to identify the register used for the first parameter in ARM calling convention.

ARM Architecture

The first parameter is passed in register [1].

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Ar0

Br4

Cr7

Dr12

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing r0 with r4 which is used for other purposes.

Assuming parameters are passed on the stack instead of registers.

In ARM architecture, the first parameter is passed using register r0.

2fill in blank

medium

Complete the code to specify how many parameters are passed in registers in ARM calling convention.

ARM Architecture

Up to [1] parameters are passed in registers before using the stack.

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A4

B2

C6

D8

Attempts:

3 left

💡 Hint

Common Mistakes

Assuming only 2 parameters are passed in registers.

Thinking all parameters are passed in registers regardless of count.

ARM calling convention passes up to 4 parameters in registers r0 to r3.

3fill in blank

hard

Fix the error in the statement about parameter passing registers in ARM.

ARM Architecture

The fifth parameter is passed in register [1].

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Ar4

Br0

Cr5

Dstack

Attempts:

3 left

💡 Hint

Common Mistakes

Assuming the fifth parameter uses r4 or r5 register.

Not knowing that parameters beyond four go to the stack.

Only the first four parameters are passed in registers (r0 to r3). The fifth parameter is passed on the stack.

4fill in blank

hard

Fill both blanks to complete the description of ARM parameter passing.

ARM Architecture

Parameters [1] to [2] are passed in registers r0 to r3.

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A1

B3

C4

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Starting count from 0 instead of 1.

Including parameter 5 as passed in registers.

Parameters 1 to 4 are passed in registers r0 to r3 in ARM calling convention.

5fill in blank

hard

Fill all three blanks to complete the ARM parameter passing code snippet.

ARM Architecture

void func(int a, int b, int c, int d, int e) {
  int reg_params[] = { [1], [2], [3], d };
  // e is passed on the stack
}

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Aa

Bb

Cc

De

Attempts:

3 left

💡 Hint

Common Mistakes

Including parameter e in the register array.

Mixing the order of parameters.

Parameters a, b, c, and d are passed in registers r0 to r3 respectively. Parameter e is passed on the stack.