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#include "matcha.h"
#include <cassert>
#include <cstdint>
#include <cstdio>
#include <sys/mman.h>
#include <unistd.h> // sysconf
// asm fns
extern "C" void thread_create();
extern "C" void yield(void* new_stack, void** old_stack);
long get_pagesize() {
return sysconf(_SC_PAGESIZE);
}
Thread::Thread(void (*fn)()) : mUserFn(fn) {
const long PAGE_SIZE = get_pagesize();
const long STACK_SIZE = 8 * PAGE_SIZE;
// create new stack
void* stack = mmap(nullptr, STACK_SIZE, PROT_WRITE | PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1 /* fd */, 0 /* offset */);
assert(stack != MAP_FAILED);
// protect last stack page (lowest addr)
int ret = mprotect(stack, PAGE_SIZE, PROT_NONE);
assert(ret == 0);
// stack grows downwards
mStackPtr = static_cast<uint8_t*>(stack) + STACK_SIZE;
{
uint64_t* stack = static_cast<uint64_t*>(mStackPtr);
*(--stack) = (uint64_t)this;
*(--stack) = (uint64_t)Thread::entry;
// initial values for yield epilog
*(--stack) = (uint64_t)thread_create;
*(--stack) = (uint64_t)0;
// initial values for callee saved regs
*(--stack) = (uint64_t)0; // rbx
*(--stack) = (uint64_t)(static_cast<uint64_t*>(mStackPtr) - 4); // rbp
*(--stack) = (uint64_t)0; // r12
*(--stack) = (uint64_t)0; // r13
*(--stack) = (uint64_t)0; // r14
*(--stack) = (uint64_t)0; // r15
mStackPtr = static_cast<void*>(stack);
}
}
void Thread::entry(void* obj) {
Thread* t = static_cast<Thread*>(obj);
puts("thread entry");
t->mUserFn();
puts("thread done");
}
void* gOriginalStack;
void yield_to(const Thread& t) {
yield(t.mStackPtr, &gOriginalStack);
}
void yield_from(Thread& t) {
yield(gOriginalStack, &t.mStackPtr);
}
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