REM
REM * This file is part of the Emeritus Pong project *
REM
REM Copyright (C) Mateusz Viste 2010
REM
REM This function checks whether the CPU supports the RDTSC instruction
REM or not. Returns 1 if RDTSC is supported, 0 otherwise.
REM

FUNCTION CheckTSC() AS BYTE
     DIM AS INTEGER i
     ' CPUID supported if can set/clear ID flag (EFLAGS bit 21).
     ASM
       pushfd
       pop edx
       pushfd
       pop eax
       Xor eax, &h200000  '' flip ID flag
       push eax
       popfd
       pushfd
       pop eax
       Xor eax, edx
       mov [i], eax
     END ASM
     IF i = 0 THEN RETURN 0

     ' TSC supported if CPUID func 1 returns with bit 4 of EDX set.
     ASM
       mov eax, 1
       cpuid
       And edx, &h10
       mov [i], edx
     END ASM
     IF i = 0 THEN RETURN 0 ELSE RETURN 1
END FUNCTION

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