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use std::sync::atomic::AtomicPtr;
use std::time::Duration;
use crate::detail::{initialize_call_frame, swap_registers, Registers};
use crate::gen_impl::DEFAULT_STACK_SIZE;
use crate::stack::{Stack, SysStack};
#[derive(Debug)]
pub struct RegContext {
/// Hold the registers while the task or scheduler is suspended
regs: Registers,
stack: Option<*const Stack>,
}
// first argument is task handle, second is thunk ptr
pub type InitFn = fn(usize, *mut usize) -> !;
impl RegContext {
pub fn empty() -> RegContext {
RegContext {
regs: Registers::new(),
stack: Option::None,
}
}
#[inline]
pub fn prefetch(&self) {
self.regs.prefetch();
}
/// Create a new context
#[allow(dead_code)]
pub fn new(init: InitFn, arg: usize, start: *mut usize, stack: &Stack) -> RegContext {
let mut ctx = RegContext::empty();
ctx.init_with(init, arg, start, stack);
ctx
}
/// init the generator register
#[inline]
pub fn init_with(&mut self, init: InitFn, arg: usize, start: *mut usize, stack: &Stack) {
// Save and then immediately load the current context,
// which we will then modify to call the given function when restoredtack
initialize_call_frame(&mut self.regs, init, arg, start, stack);
self.stack = Some(stack);
}
/// Switch contexts
///
/// Suspend the current execution context and resume another by
/// saving the registers values of the executing thread to a Context
/// then loading the registers from a previously saved Context.
#[inline]
pub fn swap(out_context: &mut RegContext, in_context: &RegContext) {
// debug!("register raw swap");
// in_context.stack_restore();
// out_context.stack_restore();
// if let Some(v)= &in_context.stack {
// unsafe {
// println!("in_context {}", v.as_ref().unwrap().size());
// }
// }
// if let Some(v)= &out_context.stack {
// unsafe {
// println!("out_context {}", v.as_ref().unwrap().size());
// }
// }
unsafe { swap_registers(&mut out_context.regs, &in_context.regs) }
//in_context.stack_reduce();
}
/// Load the context and switch. This function will never return.
#[inline]
#[allow(dead_code)]
pub fn load(to_context: &RegContext) {
let mut cur = Registers::new();
let regs: &Registers = &to_context.regs;
unsafe { swap_registers(&mut cur, regs) }
}
// pub fn stack_restore(&self) {
// match self.stack.as_ref() {
// None => {}
// Some(v) => {
// let stack = unsafe { v.as_ref().unwrap() };
// if stack.size() < 10240 {
// let mut data = stack.get_stack_data();
// println!("before restore={}",data.len());
// let left = 10240 - data.len();
// for _ in 0..left {
// data.insert(0, 0u8);
// }
// let mut idx = 0;
// for x in &data {
// if *x != 0 {
// println!("stack_restore not zero={},{}",idx, data.len());
// break;
// }
// idx += 1;
// }
// unsafe {
// let mut new_stack = Stack::new(10240);
// println!("restore {}", data.len());
// new_stack.write_stack_data(data);
// *stack.buf = new_stack.buf;
// }
// }
// }
// }
// }
// #[inline]
// pub fn stack_reduce(&self) {
// match self.stack.as_ref() {
// None => {}
// Some(v) => {
// let stack = unsafe { v.as_ref().unwrap() };
// let data = stack.get_stack_data();
//
// if data.len() == 10240 {
// let mut idx = 0;
// for x in &data {
// if *x != 0 {
// println!("stack_reduce not zero={}，len={}", idx, stack.size());
// break;
// }
// idx += 1;
// }
//
// // stack.drop_stack();
// let mut new_data = vec![];
// for x in &data[idx..] {
// new_data.push(*x);
// }
// if new_data.len() != new_data.len().next_power_of_two() {
// let v = new_data.len().next_power_of_two() - new_data.len();
// for _ in 0..v {
// new_data.insert(0, 0u8);
// }
// }
// unsafe {
// let mut new_stack = Stack::new(new_data.len());
// let before = new_data.len();
// new_stack.write_stack_data(new_data);
// println!("stack_reduce={} {}", before, new_stack.size());
// //stack.drop_stack();
// *stack.buf.lock() = new_stack.buf.into_inner();
// }
// }
//
// //println!("stack_reduce success");
// }
// }
// }
}
#[cfg(test)]
mod test {
use std::mem::transmute;
use crate::reg_context::RegContext;
use crate::stack::Stack;
const MIN_STACK: usize = 1024;
fn init_fn(arg: usize, f: *mut usize) -> ! {
let func: fn() = unsafe { transmute(f) };
func();
let ctx: &RegContext = unsafe { transmute(arg) };
RegContext::load(ctx);
unreachable!("Should never comeback");
}
#[test]
fn test_swap_context() {
static mut VAL: bool = false;
let mut cur = RegContext::empty();
fn callback() {
unsafe {
VAL = true;
}
}
let stk = Stack::new(MIN_STACK);
let ctx = RegContext::new(
init_fn,
unsafe { transmute(&cur) },
unsafe { transmute(callback as usize) },
&stk,
);
RegContext::swap(&mut cur, &ctx);
unsafe {
assert!(VAL);
}
}
#[test]
fn stack_write_read_stack(){
let mut new_stack = Stack::new(2048);
let mut v =Vec::new();
for _ in 0..2048{
v.push(0u8);
}
v[2047]=1u8;
new_stack.write_stack_data(v.clone());
let stack_data=new_stack.get_stack_data();
println!("new len= {}",stack_data.len());
println!("st {} {}",stack_data[2047],stack_data[0]);
assert_eq!(stack_data,v);
}
}