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//go:build scheduler.tasks && 386
// +build scheduler.tasks,386
package task
import "unsafe"
var systemStack uintptr
// calleeSavedRegs is the list of registers that must be saved and restored when
// switching between tasks. Also see task_stack_386.S that relies on the exact
// layout of this struct.
type calleeSavedRegs struct {
ebx uintptr
esi uintptr
edi uintptr
ebp uintptr
pc uintptr
// Pad this struct so that tasks start on a 16-byte aligned stack.
_ [3]uintptr
}
// archInit runs architecture-specific setup for the goroutine startup.
func (s *state) archInit(r *calleeSavedRegs, fn uintptr, args unsafe.Pointer) {
// Store the initial sp for the startTask function (implemented in assembly).
s.sp = uintptr(unsafe.Pointer(r))
// Initialize the registers.
// These will be popped off of the stack on the first resume of the goroutine.
// Start the function at tinygo_startTask (defined in
// src/internal/task/task_stack_386.S). This assembly code calls a function
// (passed in EBX) with a single argument (passed in ESI). After the
// function returns, it calls Pause().
r.pc = uintptr(unsafe.Pointer(&startTask))
// Pass the function to call in EBX.
// This function is a compiler-generated wrapper which loads arguments out
// of a struct pointer. See createGoroutineStartWrapper (defined in
// compiler/goroutine.go) for more information.
r.ebx = fn
// Pass the pointer to the arguments struct in ESI.
r.esi = uintptr(args)
}
func (s *state) resume() {
swapTask(s.sp, &systemStack)
}
func (s *state) pause() {
newStack := systemStack
systemStack = 0
swapTask(newStack, &s.sp)
}
// SystemStack returns the system stack pointer when called from a task stack.
// When called from the system stack, it returns 0.
func SystemStack() uintptr {
return systemStack
}
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