inline-assembly

I don't have experience in assembly, but this is what I've been working on. I would like input if I'm missing any fundamental aspects to passing parameters and calling a function via pointer in assembly. For instance I'm wondering if I supposed to restore ecx , edx , esi , edi . I read they are general purpose registers, but I couldn't find if they need to be restored? Is there any kind of cleanup I am supposed to do after a call? This is the code I have now, and it does work: #include "stdio.h" void foo(int a, int b, int c, int d) { printf("values = %d and %d and %d and %d\r\n", a, b, c, d);

I have implemented the strlen() function in different ways, including SSE2 assembly , SSE4.2 assembly and SSE2 intrinsic , I also exerted some experiments on them, with strlen() in <string.h> and strlen() in glibc . However, their performance in terms of milliseconds (time) are unexpected. My experiment environment: CentOS 7.0 + gcc 4.8.5 + Intel Xeon Following are my implementations: strlen using SSE2 assembly long strlen_sse2_asm(const char* src){ long result = 0; asm( "movl %1, %%edi\n\t" "movl $-0x10, %%eax\n\t" "pxor %%xmm0, %%xmm0\n\t" "lloop:\n\t" "addl $0x10, %%eax\n\t" "movdqu (%%edi,

I'm trying to call an assembly function from c,but i keep getting errors. .text .globl integrate .type integrate, @function integrate: push %ebp mov %esp, %ebp mov $0,%edi start_loop: cmp %edi,1024 je loop_exit mov 8(%ebp),%eax mov 12(%ebp),%ecx sub %eax,%ecx add %edi,%ecx incl %edi jmp start_loop loop_exit: movl %ebp, %esp popl %ebp ret This is my assembly function,file called integrate.s. #include <stdio.h> extern int integrate(int from,int to); void main() { printf("%d",integrate(1,10)); } Heres my c code. function.c:5:6: warning: return type of ‘main’ is not ‘int’ [-Wmain] /tmp/cciR63og.o:

I understand when to use a cobbler list (e.g. listing a register which is modified in the assembly so that it doesn't get chosen for use as an input register, etc), but I can't wrap my head around the the earlyclobber constraint & . If you list your outputs, wouldn't that already mean that inputs can't use the selected register (aside from matching digit constraints)? For example: asm( "movl $1, %0;" "addl $3, %0;" "addl $4, %1;" "addl %1, %0;" : "=g"(num_out) : "g"(num_in) : ); Would & even be needed for the output variables? The compiler should know the register that was selected for the