From 4b8cd30ed84239e528fd263ae6943ac7434fa9c6 Mon Sep 17 00:00:00 2001
From: Terraneo Federico <fede.tft@miosix.org>
Date: Thu, 12 May 2016 14:31:08 +0200
Subject: [PATCH] Added IRQgetCurrentTick() to be able to optimize getting the
current time from within ISRs, then added more inlining to cstimer.cpp,
reduced context switch time by 1us
---
.../common/interfaces-impl/cstimer.cpp | 36 ++++++++++---------
miosix/interfaces/cstimer.h | 8 +++++
2 files changed, 28 insertions(+), 16 deletions(-)
diff --git a/miosix/arch/cortexM4_stm32f4/common/interfaces-impl/cstimer.cpp b/miosix/arch/cortexM4_stm32f4/common/interfaces-impl/cstimer.cpp
index e135f052..e95fd9d8 100644
--- a/miosix/arch/cortexM4_stm32f4/common/interfaces-impl/cstimer.cpp
+++ b/miosix/arch/cortexM4_stm32f4/common/interfaces-impl/cstimer.cpp
@@ -16,6 +16,8 @@ namespace miosix_private {
void ISR_preempt();
}
+//TODO: comment me
+static const uint32_t threshold = 0xffffffff/4*3;
static long long ms32time = 0; //most significant 32 bits of counter
static long long ms32chkp = 0; //most significant 32 bits of check point
static bool lateIrq=false;
@@ -26,6 +28,16 @@ static inline long long nextInterrupt()
return ms32chkp | TIM2->CCR1;
}
+static inline long long IRQgetTick()
+{
+ //If overflow occurs while interrupts disabled
+ //counter should be checked before rollover interrupt flag
+ uint32_t counter = TIM2->CNT;
+ if((TIM2->SR & TIM_SR_UIF) && counter < threshold)
+ return (ms32time | static_cast<long long>(counter)) + 0x100000000ll;
+ return ms32time | static_cast<long long>(counter);
+}
+
void __attribute__((naked)) TIM2_IRQHandler()
{
saveContext();
@@ -35,7 +47,6 @@ void __attribute__((naked)) TIM2_IRQHandler()
void __attribute__((used)) cstirqhnd()
{
- //IRQbootlog("TIM2-IRQ\r\n");
if(TIM2->SR & TIM_SR_CC1IF || lateIrq)
{
//Checkpoint met
@@ -46,7 +57,7 @@ void __attribute__((used)) cstirqhnd()
if(ms32time==ms32chkp || lateIrq)
{
lateIrq=false;
- long long tick = ContextSwitchTimer::instance().getCurrentTick();
+ long long tick = IRQgetTick();
//Add next context switch time to the sleeping list iff this is a
//context switch
@@ -101,7 +112,7 @@ void ContextSwitchTimer::IRQsetNextInterrupt(long long tick)
{
ms32chkp = tick & 0xFFFFFFFF00000000;
TIM2->CCR1 = static_cast<unsigned int>(tick & 0xFFFFFFFF);
- if(getCurrentTick() > nextInterrupt())
+ if(IRQgetTick() > nextInterrupt())
{
NVIC_SetPendingIRQ(TIM2_IRQn);
lateIrq=true;
@@ -117,23 +128,16 @@ long long ContextSwitchTimer::getCurrentTick() const
{
bool interrupts=areInterruptsEnabled();
if(interrupts) disableInterrupts();
- //If overflow occurs while interrupts disabled
- /*
- * counter should be checked before rollover interrupt flag
- *
- */
- uint32_t counter = TIM2->CNT;
- if((TIM2->SR & TIM_SR_UIF) && counter < 0x80000000)
- {
- long long result=(ms32time | counter) + 0x100000000ll;
- if(interrupts) enableInterrupts();
- return result;
- }
- long long result=ms32time | counter;
+ long long result=IRQgetTick();
if(interrupts) enableInterrupts();
return result;
}
+long long ContextSwitchTimer::IRQgetCurrentTick() const
+{
+ return IRQgetTick();
+}
+
ContextSwitchTimer::~ContextSwitchTimer() {}
ContextSwitchTimer::ContextSwitchTimer()
diff --git a/miosix/interfaces/cstimer.h b/miosix/interfaces/cstimer.h
index 0e4ded18..f7e3f0e9 100644
--- a/miosix/interfaces/cstimer.h
+++ b/miosix/interfaces/cstimer.h
@@ -33,10 +33,18 @@ public:
/**
* Could be call both when the interrupts are enabled/disabled!
+ * TODO: investigate if it's possible to remove the possibility to call
+ * this with IRQ disabled and use IRQgetCurrentTick() instead
* \return the current tick count of the timer
*/
long long getCurrentTick() const;
+ /**
+ * \return the current tick count of the timer.
+ * Can only be called with interrupts disabled or within an IRQ
+ */
+ long long IRQgetCurrentTick() const;
+
/**
* \return the timer frequency in Hz
*/
--
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