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stm32/mphalport: Use MCU regs to detect if cycle counter is started.

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Instead of using a dedicated variable in RAM it's simpler to use the
relevant bits in the DWT register.
This commit is contained in:
Damien George 2018-03-29 16:23:52 +11:00
parent b833f170c3
commit bc3a5f1917
2 changed files with 2 additions and 6 deletions
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5
ports/stm32/mphalport.c
View File

@ -7,8 +7,6 @@
#include "usb.h"
#include "uart.h"
bool mp_hal_ticks_cpu_enabled = false;
// this table converts from HAL_StatusTypeDef to POSIX errno
const byte mp_hal_status_to_errno_table[4] = {
[HAL_OK] = 0,
@ -90,7 +88,7 @@ void mp_hal_stdout_tx_strn_cooked(const char *str, size_t len) {
}
void mp_hal_ticks_cpu_enable(void) {
if (!mp_hal_ticks_cpu_enabled) {
if (!(DWT->CTRL & DWT_CTRL_CYCCNTENA_Msk)) {
CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;
#if defined(__CORTEX_M) && __CORTEX_M == 7
// on Cortex-M7 we must unlock the DWT before writing to its registers
@ -98,7 +96,6 @@ void mp_hal_ticks_cpu_enable(void) {
#endif
DWT->CYCCNT = 0;
DWT->CTRL |= DWT_CTRL_CYCCNTENA_Msk;
mp_hal_ticks_cpu_enabled = true;
}
}

3
ports/stm32/mphalport.h
View File

@ -15,10 +15,9 @@ void mp_hal_set_interrupt_char(int c); // -1 to disable
#define mp_hal_quiet_timing_exit(irq_state) restore_irq_pri(irq_state)
#define mp_hal_delay_us_fast(us) mp_hal_delay_us(us)
extern bool mp_hal_ticks_cpu_enabled;
void mp_hal_ticks_cpu_enable(void);
static inline mp_uint_t mp_hal_ticks_cpu(void) {
if (!mp_hal_ticks_cpu_enabled) {
if (!(DWT->CTRL & DWT_CTRL_CYCCNTENA_Msk)) {
mp_hal_ticks_cpu_enable();
}
return DWT->CYCCNT;