CSCI E-92: Application Note 24

Argument passing
----------------

Passing 1 to 6 ints (passingArgs.c)
-----------------------------------

void oneArg(int one);
void twoArgs(int one, int two);
void threeArgs(int one, int two, int three);
void fourArgs(int one, int two, int three, int four);
void fiveArgs(int one, int two, int three, int four, int five);
void sixArgs(int one, int two, int three, int four, int five, int six);

int main(void) {
  oneArg(1);
  twoArgs(1, 2);
  threeArgs(1, 2, 3);
  fourArgs(1, 2, 3, 4);
  fiveArgs(1, 2, 3, 4, 5);
  sixArgs(1, 2, 3, 4, 5, 6);
	
  return 0;
}

void oneArg(int one) {
}

void twoArgs(int one, int two) {
}

void threeArgs(int one, int two, int three) {
}

void fourArgs(int one, int two, int three, int four) {
}

void fiveArgs(int one, int two, int three, int four, int five) {
}

void sixArgs(int one, int two, int three, int four, int five, int six) {
}


Disassembly of section .text.main:

00000000 <main>:
void threeArgs(int one, int two, int three);
void fourArgs(int one, int two, int three, int four);
void fiveArgs(int one, int two, int three, int four, int five);
void sixArgs(int one, int two, int three, int four, int five, int six);

int main(void) {
   0:	b580      	push	{r7, lr}
   2:	b082      	sub	sp, #8
   4:	af02      	add	r7, sp, #8
  oneArg(1);
   6:	f04f 0001 	mov.w	r0, #1
   a:	f7ff fffe 	bl	0 <main>
			a: R_ARM_THM_CALL	oneArg
  twoArgs(1, 2);
   e:	f04f 0001 	mov.w	r0, #1
  12:	f04f 0102 	mov.w	r1, #2
  16:	f7ff fffe 	bl	0 <main>
			16: R_ARM_THM_CALL	twoArgs
  threeArgs(1, 2, 3);
  1a:	f04f 0001 	mov.w	r0, #1
  1e:	f04f 0102 	mov.w	r1, #2
  22:	f04f 0203 	mov.w	r2, #3
  26:	f7ff fffe 	bl	0 <main>
			26: R_ARM_THM_CALL	threeArgs
  fourArgs(1, 2, 3, 4);
  2a:	f04f 0001 	mov.w	r0, #1
  2e:	f04f 0102 	mov.w	r1, #2
  32:	f04f 0203 	mov.w	r2, #3
  36:	f04f 0304 	mov.w	r3, #4
  3a:	f7ff fffe 	bl	0 <main>
			3a: R_ARM_THM_CALL	fourArgs
  fiveArgs(1, 2, 3, 4, 5);
  3e:	f04f 0305 	mov.w	r3, #5
  42:	9300      	str	r3, [sp, #0]
  44:	f04f 0001 	mov.w	r0, #1
  48:	f04f 0102 	mov.w	r1, #2
  4c:	f04f 0203 	mov.w	r2, #3
  50:	f04f 0304 	mov.w	r3, #4
  54:	f7ff fffe 	bl	0 <main>
			54: R_ARM_THM_CALL	fiveArgs
  sixArgs(1, 2, 3, 4, 5, 6);
  58:	f04f 0305 	mov.w	r3, #5
  5c:	9300      	str	r3, [sp, #0]
  5e:	f04f 0306 	mov.w	r3, #6
  62:	9301      	str	r3, [sp, #4]
  64:	f04f 0001 	mov.w	r0, #1
  68:	f04f 0102 	mov.w	r1, #2
  6c:	f04f 0203 	mov.w	r2, #3
  70:	f04f 0304 	mov.w	r3, #4
  74:	f7ff fffe 	bl	0 <main>
			74: R_ARM_THM_CALL	sixArgs
	
  return 0;
  78:	f04f 0300 	mov.w	r3, #0
}
  7c:	4618      	mov	r0, r3
  7e:	46bd      	mov	sp, r7
  80:	bd80      	pop	{r7, pc}
  82:	bf00      	nop

Passing 1 to 4 non-ints (passingArgsNonInt.c)
---------------------------------------------

void oneArg(int *onep);
void twoArgs(char one, char two);
void threeArgs(long long int one, char two, int *threep);
void fourArgs(char one, short int two, int three, long int four);

int main(void) {
  int i;
  
  oneArg(&i);
  twoArgs(1, 2);
  threeArgs(1, 2, &i);
  fourArgs(1, 2, 3, 4);
	
  return 0;
}

void oneArg(int *onep) {
}

void twoArgs(char one, char two) {
}

void threeArgs(long long int one, char two, int *threep) {
}

void fourArgs(char one, short int two, int three, long int four) {
}


Disassembly of section .text.main:

00000000 <main>:
void oneArg(int *onep);
void twoArgs(char one, char two);
void threeArgs(long long int one, char two, int *threep);
void fourArgs(char one, short int two, int three, long int four);

int main(void) {
   0:	b580      	push	{r7, lr}
   2:	b082      	sub	sp, #8
   4:	af00      	add	r7, sp, #0
  int i;
  
  oneArg(&i);
   6:	f107 0304 	add.w	r3, r7, #4
   a:	4618      	mov	r0, r3
   c:	f7ff fffe 	bl	0 <main>
			c: R_ARM_THM_CALL	oneArg
  twoArgs(1, 2);
  10:	f04f 0001 	mov.w	r0, #1
  14:	f04f 0102 	mov.w	r1, #2
  18:	f7ff fffe 	bl	0 <main>
			18: R_ARM_THM_CALL	twoArgs
  threeArgs(1, 2, &i);
  1c:	f107 0304 	add.w	r3, r7, #4
  20:	f04f 0001 	mov.w	r0, #1
  24:	f04f 0100 	mov.w	r1, #0
  28:	f04f 0202 	mov.w	r2, #2
  2c:	f7ff fffe 	bl	0 <main>
			2c: R_ARM_THM_CALL	threeArgs
  fourArgs(1, 2, 3, 4);
  30:	f04f 0001 	mov.w	r0, #1
  34:	f04f 0102 	mov.w	r1, #2
  38:	f04f 0203 	mov.w	r2, #3
  3c:	f04f 0304 	mov.w	r3, #4
  40:	f7ff fffe 	bl	0 <main>
			40: R_ARM_THM_CALL	fourArgs
	
  return 0;
  44:	f04f 0300 	mov.w	r3, #0
}
  48:	4618      	mov	r0, r3
  4a:	f107 0708 	add.w	r7, r7, #8
  4e:	46bd      	mov	sp, r7
  50:	bd80      	pop	{r7, pc}
  52:	bf00      	nop