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53 lines
1.6 KiB
C
53 lines
1.6 KiB
C
#ifndef COSMOPOLITAN_LIBC_NEXGEN32E_RDTSC_H_
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#define COSMOPOLITAN_LIBC_NEXGEN32E_RDTSC_H_
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#if !(__ASSEMBLER__ + __LINKER__ + 0)
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COSMOPOLITAN_C_START_
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/**
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* Reads CPU timestamp counter.
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*
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* This macro inhibits compiler magic.
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* This macro does not inhibit CPU magic.
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*
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* @see X86_HAVE(INVTSC)
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*/
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#define rdtsc() __RDTSC("rdtsc")
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/**
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* Reads CPU timestamp counter w/ full serialization.
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*
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* This macro inhibits CPU magic.
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* This macro inhibits compiler magic.
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*
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* The clock isn't read until:
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*
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* 1. previous instructions finish executing; and
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* 2. previous loads are globally visible; and
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* 3. previous stores are globally visible.
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*
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* Later instructions won't dispatch until RDTSC completes.
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*
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* @see X86_HAVE(INVTSC)
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*/
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#define mfence_lfence_rdtsc_lfence() \
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__RDTSC("mfence\n\tlfence\n\trdtsc\n\tlfence")
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#ifdef __x86__
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#define __RDTSC(ASM) \
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({ \
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uint64_t Rax, Rdx; \
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asm volatile(ASM : "=a"(Rax), "=d"(Rdx) : /* no inputs */ : "memory"); \
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Rdx << 32 | Rax; \
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})
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#elif defined(__aarch64__)
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#define __RDTSC(ASM) \
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({ \
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uint64_t _Ts; \
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asm volatile("mrs\t%0,cntvct_el0" : "=r"(_Ts)); \
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_Ts * 48; /* the fudge factor */ \
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})
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#endif
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COSMOPOLITAN_C_END_
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#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
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#endif /* COSMOPOLITAN_LIBC_NEXGEN32E_RDTSC_H_ */
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