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Assembly based loop for timing test

pull/4666/head
Chris 2017-06-30 20:33:58 +01:00
parent 3df42bcfb4
commit 562a548053
1 changed files with 43 additions and 3 deletions
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46
TESTS/mbed_hal/flash/functional_tests/main.cpp
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@ -52,8 +52,49 @@ static void erase_range(flash_t *flash, uint32_t addr, uint32_t size)
size = size > sector_size ? size - sector_size : 0;
}
}
#ifdef __CC_ARM
MBED_NOINLINE
__asm static void delay_loop(uint32_t count)
{
1
SUBS a1, a1, #1
BCS %BT1
BX lr
}
#elif defined (__ICCARM__)
MBED_NOINLINE
static void delay_loop(uint32_t count)
{
__asm volatile(
"loop: \n"
" SUBS %0, %0, #1 \n"
" BCS.n loop\n"
: "+r" (count)
:
: "cc"
);
}
#else // GCC
MBED_NOINLINE
static void delay_loop(uint32_t count)
{
__asm__ volatile (
"%=:\n\t"
#if defined(__thumb__) && !defined(__thumb2__)
"SUB %0, #1\n\t"
#else
"SUBS %0, %0, #1\n\t"
#endif
"BCS %=b\n\t"
: "+l" (count)
:
: "cc"
);
}
#endif
__attribute__((noinline)) static int time_cpu_cycles(uint32_t cycles)
MBED_NOINLINE
static int time_cpu_cycles(uint32_t cycles)
{
Timer timer;
timer.start();
@ -61,8 +102,7 @@ __attribute__((noinline)) static int time_cpu_cycles(uint32_t cycles)
int timer_start = timer.read_us();
volatile uint32_t delay = (volatile uint32_t)cycles;
while (delay--);
delay_loop(delay);
int timer_end = timer.read_us();
timer.stop();