mirror of https://github.com/bsnes-emu/bsnes.git
115 lines
3.0 KiB
C
115 lines
3.0 KiB
C
/*
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libco.x86 (2016-09-14)
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author: byuu
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license: public domain
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*/
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#define LIBCO_C
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#include "libco.h"
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#include "settings.h"
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#include <assert.h>
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#include <stdlib.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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#if defined(__clang__) || defined(__GNUC__)
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#define fastcall __attribute__((fastcall))
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#elif defined(_MSC_VER)
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#define fastcall __fastcall
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#else
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#error "libco: please define fastcall macro"
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#endif
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static thread_local long co_active_buffer[64];
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static thread_local cothread_t co_active_handle = 0;
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static void (fastcall *co_swap)(cothread_t, cothread_t) = 0;
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#ifdef LIBCO_MPROTECT
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alignas(4096)
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#else
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section(text)
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#endif
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/* ABI: fastcall */
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static const unsigned char co_swap_function[4096] = {
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0x89, 0x22, /* mov [edx],esp */
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0x8b, 0x21, /* mov esp,[ecx] */
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0x58, /* pop eax */
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0x89, 0x6a, 0x04, /* mov [edx+ 4],ebp */
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0x89, 0x72, 0x08, /* mov [edx+ 8],esi */
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0x89, 0x7a, 0x0c, /* mov [edx+12],edi */
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0x89, 0x5a, 0x10, /* mov [edx+16],ebx */
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0x8b, 0x69, 0x04, /* mov ebp,[ecx+ 4] */
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0x8b, 0x71, 0x08, /* mov esi,[ecx+ 8] */
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0x8b, 0x79, 0x0c, /* mov edi,[ecx+12] */
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0x8b, 0x59, 0x10, /* mov ebx,[ecx+16] */
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0xff, 0xe0, /* jmp eax */
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};
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#ifdef _WIN32
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#include <windows.h>
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static void co_init() {
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#ifdef LIBCO_MPROTECT
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DWORD old_privileges;
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VirtualProtect((void*)co_swap_function, sizeof co_swap_function, PAGE_EXECUTE_READ, &old_privileges);
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#endif
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}
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#else
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#include <unistd.h>
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#include <sys/mman.h>
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static void co_init() {
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#ifdef LIBCO_MPROTECT
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unsigned long addr = (unsigned long)co_swap_function;
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unsigned long base = addr - (addr % sysconf(_SC_PAGESIZE));
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unsigned long size = (addr - base) + sizeof co_swap_function;
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mprotect((void*)base, size, PROT_READ | PROT_EXEC);
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#endif
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}
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#endif
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static void crash() {
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assert(0); /* called only if cothread_t entrypoint returns */
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}
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cothread_t co_active() {
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if(!co_active_handle) co_active_handle = &co_active_buffer;
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return co_active_handle;
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}
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cothread_t co_create(unsigned int size, void (*entrypoint)(void)) {
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cothread_t handle;
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if(!co_swap) {
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co_init();
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co_swap = (void (fastcall*)(cothread_t, cothread_t))co_swap_function;
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}
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if(!co_active_handle) co_active_handle = &co_active_buffer;
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size += 256; /* allocate additional space for storage */
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size &= ~15; /* align stack to 16-byte boundary */
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if(handle = (cothread_t)malloc(size)) {
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long *p = (long*)((char*)handle + size); /* seek to top of stack */
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*--p = (long)crash; /* crash if entrypoint returns */
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*--p = (long)entrypoint; /* start of function */
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*(long*)handle = (long)p; /* stack pointer */
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}
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return handle;
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}
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void co_delete(cothread_t handle) {
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free(handle);
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}
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void co_switch(cothread_t handle) {
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register cothread_t co_previous_handle = co_active_handle;
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co_swap(co_active_handle = handle, co_previous_handle);
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}
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#ifdef __cplusplus
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}
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#endif
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