RetroArch/libretro-sdk/libco/x86.c

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/*
libco.x86 (2009-10-12)
author: byuu
license: public domain
*/
#define LIBCO_C
#include <libco.h>
#include <assert.h>
#include <stdlib.h>
#ifdef __cplusplus
extern "C" {
#endif
#if defined(_MSC_VER)
#define fastcall __fastcall
#elif defined(__GNUC__)
#define fastcall __attribute__((fastcall))
#else
#error "libco: please define fastcall macro"
#endif
static thread_local long co_active_buffer[64];
static thread_local cothread_t co_active_handle = 0;
static void (fastcall *co_swap)(cothread_t, cothread_t) = 0;
//ABI: fastcall
static unsigned char co_swap_function[] = {
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0x89, 0x22, /* mov [edx],esp */
0x8b, 0x21, /* mov esp,[ecx] */
0x58, /* pop eax */
0x89, 0x6a, 0x04, /* mov [edx+0x04],ebp */
0x89, 0x72, 0x08, /* mov [edx+0x08],esi */
0x89, 0x7a, 0x0c, /* mov [edx+0x0c],edi */
0x89, 0x5a, 0x10, /* mov [edx+0x10],ebx */
0x8b, 0x69, 0x04, /* mov ebp,[ecx+0x04] */
0x8b, 0x71, 0x08, /* mov esi,[ecx+0x08] */
0x8b, 0x79, 0x0c, /* mov edi,[ecx+0x0c] */
0x8b, 0x59, 0x10, /* mov ebx,[ecx+0x10] */
0xff, 0xe0, /* jmp eax */
};
#ifdef _WIN32
#include <windows.h>
void co_init(void)
{
DWORD old_privileges;
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VirtualProtect(co_swap_function,
sizeof co_swap_function, PAGE_EXECUTE_READWRITE, &old_privileges);
}
#else
#include <unistd.h>
#include <sys/mman.h>
void co_init(void)
{
unsigned long addr = (unsigned long)co_swap_function;
unsigned long base = addr - (addr % sysconf(_SC_PAGESIZE));
unsigned long size = (addr - base) + sizeof co_swap_function;
mprotect((void*)base, size, PROT_READ | PROT_WRITE | PROT_EXEC);
}
#endif
static void crash(void)
{
assert(0); /* called only if cothread_t entrypoint returns */
}
cothread_t co_active(void)
{
if(!co_active_handle)
co_active_handle = &co_active_buffer;
return co_active_handle;
}
cothread_t co_create(unsigned int size, void (*entrypoint)(void))
{
cothread_t handle;
if(!co_swap)
{
co_init();
co_swap = (void (fastcall*)(cothread_t, cothread_t))co_swap_function;
}
if(!co_active_handle)
co_active_handle = &co_active_buffer;
size += 256; /* allocate additional space for storage */
size &= ~15; /* align stack to 16-byte boundary */
if(handle = (cothread_t)malloc(size))
{
long *p = (long*)((char*)handle + size); /* seek to top of stack */
*--p = (long)crash; /* crash if entrypoint returns */
*--p = (long)entrypoint; /* start of function */
*(long*)handle = (long)p; /* stack pointer */
}
return handle;
}
void co_delete(cothread_t handle)
{
free(handle);
}
void co_switch(cothread_t handle)
{
register cothread_t co_previous_handle = co_active_handle;
co_swap(co_active_handle = handle, co_previous_handle);
}
#ifdef __cplusplus
}
#endif