diff options
Diffstat (limited to 'c/src/lib/libbsp/arm/gumstix/timer/timer.c')
-rw-r--r-- | c/src/lib/libbsp/arm/gumstix/timer/timer.c | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/c/src/lib/libbsp/arm/gumstix/timer/timer.c b/c/src/lib/libbsp/arm/gumstix/timer/timer.c new file mode 100644 index 0000000000..7eb3d5b811 --- /dev/null +++ b/c/src/lib/libbsp/arm/gumstix/timer/timer.c @@ -0,0 +1,75 @@ +/** + * @file + * @brief PXA255 timer + */ + +/* + * PXA255 timer by Yang Xi <hiyangxi@gmail.com> + * Copyright (c) 2004 by Jay Monkman <jtm@lopingdog.com> + * + * The license and distribution terms for this file may be + * found in the file LICENSE in this distribution or at + * http://www.rtems.org/license/LICENSE. + */ + +#include <bsp.h> +#include <rtems.h> +#include <rtems/btimer.h> +#include <pxa255.h> + +uint32_t tstart; +static uint32_t tick_time; +bool benchmark_timer_find_average_overhead; + +bool benchmark_timer_is_initialized = false; + +/* + * Use the timer count register to measure. + * The frequency of it is 3.4864MHZ + * The longest period we are able to capture is 4G/3.4864MHZ + */ +void benchmark_timer_initialize(void) +{ + tick_time = XSCALE_OS_TIMER_TCR; +} + +/* + * The following controls the behavior of Read_timer(). + * + * AVG_OVEREHAD is the overhead for starting and stopping the timer. It + * is usually deducted from the number returned. + * + * LEAST_VALID is the lowest number this routine should trust. Numbers + * below this are "noise" and zero is returned. + */ + +#define AVG_OVERHEAD 0 /* It typically takes X.X microseconds */ + /* (Y countdowns) to start/stop the timer. */ + /* This value is in microseconds. */ +#define LEAST_VALID 1 /* Don't trust a clicks value lower than this */ + +benchmark_timer_t benchmark_timer_read(void) +{ + + uint32_t total; + total = XSCALE_OS_TIMER_TCR; + if(total>=tick_time) + total -= tick_time; + else + total += 0xffffffff - tick_time; /*Round up but not overflow*/ + + if ( benchmark_timer_find_average_overhead == true ) + return total; /*Counter cycles*/ + + if ( total < LEAST_VALID ) + return 0; /* below timer resolution */ + + return total; +} + +void benchmark_timer_disable_subtracting_average_overhead( + bool find_flag +) +{ + benchmark_timer_find_average_overhead = find_flag; +} |