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Nuvoton: Remove dead code nu_delay_cycle_x4(...) 

Originally, nu_delay_cycle_x4(...) is borrowed from mbed test code for delay
cycle. Currently, it is not used on Nuvoton targets. If delay cycle is needed,
use wait_ns(...) instead which has strict implementation and has passed tests.
pull/11160/head
Chun-Chieh Li 2019-08-05 09:32:35 +08:00
parent 818c1d6f0f
commit 413d127586
2 changed files with 0 additions and 65 deletions
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62
targets/TARGET_NUVOTON/nu_timer.c
View File

@ -65,65 +65,3 @@ void nu_busy_wait_us(uint32_t us)
prev = cur;
}
}
/* Delay 4 cycles per round by hand-counting instruction cycles
*
* The delay function here is implemented by just hand-counting instruction cycles rather than preferred
* H/W timer since it is to use in cases where H/W timer is not available. Usually, it can delay at least
* 4-cycles per round.
*
* In modern pipeline core, plus flash performance and other factors, we cannot rely accurately on hand-
* counting instruction cycles for expected delay cycles.
*/
#if defined(__CC_ARM)
MBED_NOINLINE
__asm void nu_delay_cycle_x4(uint32_t rounds)
{
// AStyle should not format inline assembly
// *INDENT-OFF*
1
#if !defined(__CORTEX_M0)
NOP // 1 cycle
#endif
SUBS a1, a1, #1 // 1 cycle
BCS %BT1 // 3 cycles(M0)/2 cycles(non-M0)
BX lr
// *INDENT-ON*
}
#elif defined (__ICCARM__)
MBED_NOINLINE
void nu_delay_cycle_x4(uint32_t rounds)
{
__asm volatile(
"loop: \n"
#if !defined(__CORTEX_M0)
" NOP \n" // 1 cycle
#endif
" SUBS %0, %0, #1 \n" // 1 cycle
" BCS.n loop\n" // 3 cycles(M0)/2 cycles(non-M0)
: "+r"(rounds)
:
: "cc"
);
}
#elif defined ( __GNUC__ ) || (defined(__ARMCC_VERSION) && (__ARMCC_VERSION >= 6010050))
MBED_NOINLINE
void nu_delay_cycle_x4(uint32_t rounds)
{
__asm__ volatile(
"%=:\n\t"
#if !defined(__CORTEX_M0)
"NOP\n\t" // 1 cycle
#endif
#if defined(__thumb__) && !defined(__thumb2__) && !defined(__ARMCC_VERSION)
"SUB %0, #1\n\t" // 1 cycle
#else
"SUBS %0, %0, #1\n\t" // 1 cycle
#endif
"BCS %=b\n\t" // 3 cycles(M0)/2 cycles(non-M0)
: "+l"(rounds)
:
: "cc"
);
}
#endif

3
targets/TARGET_NUVOTON/nu_timer.h
View File

@ -74,9 +74,6 @@ void nu_countdown_free(struct nu_countdown_ctx_s *ctx);
*/
void nu_busy_wait_us(uint32_t us);
/* Delay 4 cycles per round by hand-counting instruction cycles */
void nu_delay_cycle_x4(uint32_t rounds);
#ifdef __cplusplus
}
#endif