3c55689566
This commit refactors both determining the current time and sleeping for
a given time. It also improves precision for many chips.
* The nrf chips had a long-standing TODO comment about a slightly
inaccurate clock. This should now be fixed.
* The SAM D2x/D5x chips may have a slightly more accurate clock,
although probably within the error margin of the RTC. Also, by
working with RTC ticks and converting in the least number of places,
code size is often slightly reduced (usually just a few bytes, up to
around 1kB in some cases).
* I believe the HiFive1 rev B timer was slightly wrong (32768Hz vs
30517.6Hz). Because the datasheet says the clock runs at 32768Hz,
I've used the same conversion code here as in the nrf and sam cases.
* I couldn't test both stm32 timers, so I kept them as they currently
are. It may be possible to make them more efficient by using the
native tick frequency instead of using microseconds everywhere.
69 строки
1,3 КиБ
Go
69 строки
1,3 КиБ
Go
// +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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func postinit() {}
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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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abort()
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}
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const asyncScheduler = false
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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.Register16)(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 abort() {
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// Make sure the QEMU process exits.
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testFinisher.Set(0x5555) // FINISHER_PASS
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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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