nkeynes@225: #include "../lib.h"
nkeynes@225: #define TMU_CHANNEL 2
nkeynes@262: #define BASE_TICKS_PER_US 200
nkeynes@262: #define CLOCK_DIVIDER 16
nkeynes@225: #define TOCR 0xFFD80000  /* Output control register */
nkeynes@225: #define TSTR 0xFFD80004  /* Start register */
nkeynes@225: #define TCOR(c) (0xFFD80008 + (c*12))  /* Constant register */
nkeynes@225: #define TCNT(c) (0xFFD8000C + (c*12))  /* Count register */
nkeynes@225: #define TCR(c)  (0xFFD80010 + (c*12))  /* Control register */
nkeynes@225: 
nkeynes@225: /**
nkeynes@225:  * Initialize the on-chip timer controller. We snag TMU channel 2 in its
nkeynes@225:  * highest resolution mode, and start it counting down from max_int. 
nkeynes@225:  */
nkeynes@272: void timer_init() {
nkeynes@262:     unsigned int val = byte_read(TSTR);
nkeynes@262:     byte_write( TSTR, val & (~(1<<TMU_CHANNEL)) ); /* Stop counter */
nkeynes@225:     long_write( TCOR(TMU_CHANNEL), 0xFFFFFFFF );
nkeynes@225:     long_write( TCNT(TMU_CHANNEL), 0xFFFFFFFF );
nkeynes@262:     word_write( TCR(TMU_CHANNEL), 0x00000000 );
nkeynes@272: }
nkeynes@272: 
nkeynes@272: void timer_run() {
nkeynes@272:     byte_write( TSTR, byte_read(TSTR) | (1<<TMU_CHANNEL) );
nkeynes@272: }
nkeynes@272: 
nkeynes@272: void timer_start() {
nkeynes@272:     timer_init();
nkeynes@272:     timer_run();
nkeynes@225: }
nkeynes@225: 
nkeynes@225: /**
nkeynes@225:  * Report the current value of TMU2.
nkeynes@225:  */
nkeynes@262: unsigned int timer_gettime() {
nkeynes@225:     return long_read(TCNT(TMU_CHANNEL));
nkeynes@225: }
nkeynes@225: 
nkeynes@225: /**
nkeynes@225:  * Stop TMU2 and report the current value.
nkeynes@225:  */
nkeynes@262: unsigned int timer_stop() {
nkeynes@225:     long_write( TSTR, long_read(TSTR) & (~(1<<TMU_CHANNEL)) );
nkeynes@225:     return long_read( TCNT(TMU_CHANNEL) );
nkeynes@225: }
nkeynes@225: 
nkeynes@225: 
nkeynes@225: /**
nkeynes@225:  * Convert the supplied timer value to a number of micro seconds since the timer
nkeynes@225:  * was started.
nkeynes@225:  */
nkeynes@262: unsigned int timer_to_microsecs( unsigned int value ) {
nkeynes@262:     return (0xFFFFFFFF - value) * CLOCK_DIVIDER / BASE_TICKS_PER_US;
nkeynes@225: }
nkeynes@262: 
nkeynes@262: unsigned int timer_gettime_us() {
nkeynes@262:     return timer_to_microsecs( timer_gettime() );
nkeynes@262: }