85 строки
1,6 КиБ
Go
85 строки
1,6 КиБ
Go
//go:build tinygo.riscv && virt && qemu
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// +build tinygo.riscv,virt,qemu
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package runtime
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import (
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"device/riscv"
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"runtime/volatile"
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"unsafe"
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)
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// This file implements the VirtIO RISC-V interface implemented in QEMU, which
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// is an interface designed for emulation.
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type timeUnit int64
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var timestamp timeUnit
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//export main
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func main() {
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preinit()
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run()
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exit(0)
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}
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func ticksToNanoseconds(ticks timeUnit) int64 {
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return int64(ticks)
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}
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func nanosecondsToTicks(ns int64) timeUnit {
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return timeUnit(ns)
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}
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func sleepTicks(d timeUnit) {
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// TODO: actually sleep here for the given time.
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timestamp += d
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}
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func ticks() timeUnit {
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return timestamp
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}
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// Memory-mapped I/O as defined by QEMU.
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// Source: https://github.com/qemu/qemu/blob/master/hw/riscv/virt.c
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// Technically this is an implementation detail but hopefully they won't change
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// the memory-mapped I/O registers.
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var (
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// UART0 output register.
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stdoutWrite = (*volatile.Register8)(unsafe.Pointer(uintptr(0x10000000)))
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// SiFive test finisher
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testFinisher = (*volatile.Register32)(unsafe.Pointer(uintptr(0x100000)))
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)
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func putchar(c byte) {
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stdoutWrite.Set(uint8(c))
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}
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func getchar() byte {
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// dummy, TODO
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return 0
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}
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func buffered() int {
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// dummy, TODO
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return 0
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}
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func abort() {
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exit(1)
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}
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func exit(code int) {
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// Make sure the QEMU process exits.
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if code == 0 {
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testFinisher.Set(0x5555) // FINISHER_PASS
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} else {
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// Exit code is stored in the upper 16 bits of the 32 bit value.
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testFinisher.Set(uint32(code)<<16 | 0x3333) // FINISHER_FAIL
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}
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// Lock up forever (as a fallback).
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for {
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riscv.Asm("wfi")
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}
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}
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