Hello guys
I am new to this forum and to gcc/g++ and I need to know exactly
how to declare a function in g++. I wrote a C++ program to calculate
the GCD of two numbers, I've tested it and it works. I wanted to
compile the program and target a mips processor so I issued the
following command
"sde-c++ -c -mtune=r3k -T ph.ld -O2 GCD.cpp -o GCD.bin" The program
compiled fine, but would link because the linker for some reason did
not reconize the iostream header file, no idea why?
So I used the -c option and like I said it compiled fine. However
when I look over the disassembled list the assembly code is not quite
correct, it looks as if the compiler placed the function "GCD" before
the main() and before any initialization period. I read over the
first few instructions and sure enough I was right because the
function is placed before any initialization the program starts off
within the function and can't get out its in an infinite loop and
can't get out. I figured it must have something to do with how I am
declaring the function and I wanted to ask you guys. Some one help me
please. The C++ code is pasted in below as well as the disassemble
list.
#include "iostream"
#include "iomanip"
#include "math.h"
using namespace std;
unsigned int GCD_FUNCT( unsigned int, unsigned int );
int main() {
unsigned int ARRAY[32], GCD[16];
unsigned int Loop_Control_V, Reg1, Reg2, new_value;
for ( unsigned int i = 0; i < 31; ++ i ) {
new_value = i + ( 3 * (4) );
if ( new_value % 2 != 0 ) {
new_value = new_value * 4;
}
else{
new_value = new_value * 10;
}
ARRAY[i] = new_value;
}
Loop_Control_V = 0;
while ( Loop_Control_V < 30 ) {
if ( ARRAY[Loop_Control_V] > ARRAY[Loop_Control_V +
1] ) {
Reg1 = ARRAY[Loop_Control_V];
Reg2 = ARRAY[Loop_Control_V + 1];
}
else {
Reg1 = ARRAY[Loop_Control_V + 1];
Reg2 = ARRAY[Loop_Control_V];
}
GCD[Loop_Control_V] = GCD_FUNCT(Reg1,Reg2);
Loop_Control_V = Loop_Control_V + 1;
}
return 0;
}
unsigned int GCD_FUNCT( unsigned int REGa, unsigned int REGb) {
unsigned int temp1, temp2, GCD;
temp1 = REGa;
temp2 = REGb;
while ( temp1 != temp2 ) {
if ( temp1 > temp2 ) {
temp1 = temp1 - temp2;
}
else {
temp2 = temp2 - temp1;
}
}
GCD = temp1;
return GCD;
}
-- Disassemble list.
GCD.bin: file format elf32-tradbigmips
Disassembly of section .text:
00000000 <_Z9GCD_FUNCTjj>:
_Z9GCD_FUNCTjj():
0: 10850007 beq a0,a1,20 <_Z9GCD_FUNCTjj+0x20>
4: 00000000 nop
8: 00a4102b sltu v0,a1,a0
c: 10400006 beqz v0,28 <_Z9GCD_FUNCTjj+0x28>
10: 00000000 nop
14: 00852023 subu a0,a0,a1
18: 1485fffb bne a0,a1,8 <_Z9GCD_FUNCTjj+0x8>
1c: 00000000 nop
20: 03e00008 jr ra
24: 00801021 move v0,a0
28: 1000fff5 b 0 <_Z9GCD_FUNCTjj>
2c: 00a42823 subu a1,a1,a0
00000030 <main>:
main():
30: 27bdff20 addiu sp,sp,-224
34: 27a80010 addiu t0,sp,16
38: afbf00d8 sw ra,216(sp)
3c: afb100d4 sw s1,212(sp)
40: afb000d0 sw s0,208(sp)
44: 00002821 move a1,zero
48: 01003021 move a2,t0
4c: 24a2000c addiu v0,a1,12
50: 00021880 sll v1,v0,0x2
54: 24a50001 addiu a1,a1,1
58: 30440001 andi a0,v0,0x1
5c: 00621821 addu v1,v1,v0
60: 2ca7001f sltiu a3,a1,31
64: 14800002 bnez a0,70 <main+0x40>
68: 00021080 sll v0,v0,0x2
6c: 00031040 sll v0,v1,0x1
70: acc20000 sw v0,0(a2)
74: 14e0fff5 bnez a3,4c <main+0x1c>
78: 24c60004 addiu a2,a2,4
7c: 01008021 move s0,t0
80: 2411001d li s1,29
84: 8e060000 lw a2,0(s0)
88: 8e030004 lw v1,4(s0)
8c: 2631ffff addiu s1,s1,-1
90: 0066382b sltu a3,v1,a2
94: 00c02021 move a0,a2
98: 14e00003 bnez a3,a8 <main+0x78>
9c: 00602821 move a1,v1
a0: 00602021 move a0,v1
a4: 00c02821 move a1,a2
a8: 0c000000 jal 0 <_Z9GCD_FUNCTjj>
ac: 00000000 nop
b0: ae020080 sw v0,128(s0)
b4: 0621fff3 bgez s1,84 <main+0x54>
b8: 26100004 addiu s0,s0,4
bc: 8fbf00d8 lw ra,216(sp)
c0: 8fb100d4 lw s1,212(sp)
c4: 8fb000d0 lw s0,208(sp)
c8: 00001021 move v0,zero
cc: 03e00008 jr ra
d0: 27bd00e0 addiu sp,sp,224
000000d4 <_Z41__static_initialization_and_destruction_0ii>:
_Z41__static_initialization_and_destruction_0ii():
d4: 27bdffe0 addiu sp,sp,-32
d8: 38860001 xori a2,a0,0x1
dc: 38a5ffff xori a1,a1,0xffff
e0: afb00010 sw s0,16(sp)
e4: 2cc30001 sltiu v1,a2,1
e8: 2cb00001 sltiu s0,a1,1
ec: afb10014 sw s1,20(sp)
f0: 02031024 and v0,s0,v1
f4: 00808821 move s1,a0
f8: 3c040000 lui a0,0x0
fc: afbf0018 sw ra,24(sp)
100: 14400010 bnez v0,144
<_Z41__static_initialization_and_destruction_0ii+0x70>
104: 24840000 addiu a0,a0,0
108: 2e280001 sltiu t0,s1,1
10c: 3c090000 lui t1,0x0
110: 02083824 and a3,s0,t0
114: 14e00006 bnez a3,130
<_Z41__static_initialization_and_destruction_0ii+0x5c>
118: 25240000 addiu a0,t1,0
11c: 8fbf0018 lw ra,24(sp)
120: 8fb10014 lw s1,20(sp)
124: 8fb00010 lw s0,16(sp)
128: 03e00008 jr ra
12c: 27bd0020 addiu sp,sp,32
130: 8fbf0018 lw ra,24(sp)
134: 8fb10014 lw s1,20(sp)
138: 8fb00010 lw s0,16(sp)
13c: 08000000 j 0 <_Z9GCD_FUNCTjj>
140: 27bd0020 addiu sp,sp,32
144: 0c000000 jal 0 <_Z9GCD_FUNCTjj>
148: 00000000 nop
14c: 1000ffef b 10c
<_Z41__static_initialization_and_destruction_0ii
+0x38>
150: 2e280001 sltiu t0,s1,1
00000154 <_GLOBAL__I_main>:
_GLOBAL__I_main():
154: 24040001 li a0,1
158: 08000035 j d4
<_Z41__static_initialization_and_destruction_0ii>
15c: 3405ffff li a1,0xffff
00000160 <_GLOBAL__D_main>:
_GLOBAL__D_main():
160: 00002021 move a0,zero
164: 08000035 j d4
<_Z41__static_initialization_and_destruction_0ii>
168: 3405ffff li a1,0xffff
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