start implementing the libretro interface. (not working yet)

1 files changed, 117 insertions, 0 deletions

diff --git a/libco/x86.c b/libco/x86.c
new file mode 100644
index 0000000..5daffd9
--- /dev/null
+++ b/libco/x86.c
@@ -0,0 +1,117 @@
+/*
+  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[] = {
+  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;
+   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