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Fix timing issues found in "Flash - clock and cache test" #4666

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Merged
merged 5 commits into from
Jul 13, 2017
Merged

Fix timing issues found in "Flash - clock and cache test" #4666

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92e4a1f
Fix timing issues found in "Flash - clock and cache test"
chrissnow Jun 29, 2017
3df42bc
Toolchain independent noinline
chrissnow Jun 30, 2017
562a548
Assembly based loop for timing test
chrissnow Jun 30, 2017
ed8b378
Code tidy
chrissnow Jun 30, 2017
8365d9d
Remove volatile
chrissnow Jun 30, 2017
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46 changes: 43 additions & 3 deletions TESTS/mbed_hal/flash/functional_tests/main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -52,17 +52,57 @@ 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
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I got a question regarding this 1, is it required? I came across this code today, and wondering if this is line is needed?

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

MBED_NOINLINE
static int time_cpu_cycles(uint32_t cycles)
{
Timer timer;
timer.start();

int timer_start = timer.read_us();

volatile uint32_t delay = (volatile uint32_t)cycles;
while (delay--);

uint32_t delay = cycles;
delay_loop(delay);
int timer_end = timer.read_us();

timer.stop();
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21 changes: 21 additions & 0 deletions platform/mbed_toolchain.h
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Original file line number Diff line number Diff line change
Expand Up @@ -137,6 +137,27 @@
#endif
#endif

/** MBED_NOINLINE
* Declare a function that must not be inlined.
*
* @code
* #include "mbed_toolchain.h"
*
* MBED_NOINLINE void foo() {
*
* }
* @endcode
*/
#ifndef MBED_NOINLINE
#if defined(__GNUC__) || defined(__clang__) || defined(__CC_ARM)
#define MBED_NOINLINE __attribute__((noinline))
#elif defined(__ICCARM__)
#define MBED_NOINLINE _Pragma("inline=never")
#else
#define MBED_NOINLINE
#endif
#endif

/** MBED_FORCEINLINE
* Declare a function that must always be inlined. Failure to inline
* such a function will result in an error.
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