21 lines
519 B
C
21 lines
519 B
C
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#include <sys/types.h>
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void
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read_tsc(u32_t *hi, u32_t *lo)
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{
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/* Read Clock Cycle Counter (CCNT). Intel calls it Time Stamp Counter (TSC) */
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u32_t ccnt;
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/* Get value from the Performance Monitors Cycle Counter Register.
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* See ARM Architecture Reference Manual B5.1.113.
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*/
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asm volatile ("MRC p15, 0, %0, c9, c13, 0\t\n" : "=r" (ccnt) : : "%0");
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/* The ARMv7-A clock cycle counter is only 32-bits, but read_tsc is
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* expected to return a 64-bit value. hi is therefore always 0.
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*/
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*hi = 0;
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*lo = ccnt;
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}
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