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Add an RDTSC implementation to the x86 emulator.

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This instruction is being used in some debug VBIOSes.  This implementation
doesn't even try to be accurate.  Instead, it just increments the counter by a
fixed amount every time an rdtsc instruction in encountered, to avoid divides by
zero.
This commit is contained in:
Aaron Plattner 2007-02-06 14:57:22 -08:00 • committed by Keith Packard
parent 8a16682892
commit d3f507c2a2
1 changed files with 35 additions and 1 deletions
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36
hw/xfree86/x86emu/ops2.c
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@ -63,6 +63,40 @@ static void x86emuOp2_illegal_op(
#define xorl(a,b) ((a) && !(b)) || (!(a) && (b))
/****************************************************************************
REMARKS:
Handles opcode 0x0f,0x31
****************************************************************************/
static void x86emuOp2_rdtsc(u8 X86EMU_UNUSED(op2))
{
#ifdef __HAS_LONG_LONG__
static u64 counter = 0;
#else
static u32 counter = 0;
#endif
counter += 0x10000;
/* read timestamp counter */
/*
* Note that instead of actually trying to accurately measure this, we just
* increase the counter by a fixed amount every time we hit one of these
* instructions. Feel free to come up with a better method.
*/
START_OF_INSTR();
DECODE_PRINTF("RDTSC\n");
TRACE_AND_STEP();
#ifdef __HAS_LONG_LONG__
M.x86.R_EAX = counter & 0xffffffff;
M.x86.R_EDX = counter >> 32;
#else
M.x86.R_EAX = counter;
M.x86.R_EDX = 0;
#endif
DECODE_CLEAR_SEGOVR();
END_OF_INSTR();
}
/****************************************************************************
REMARKS:
Handles opcode 0x0f,0x80-0x8F
@ -2580,7 +2614,7 @@ void (*x86emu_optab2[256])(u8) =
/* 0x2f */ x86emuOp2_illegal_op,
/* 0x30 */ x86emuOp2_illegal_op,
/* 0x31 */ x86emuOp2_illegal_op,
/* 0x31 */ x86emuOp2_rdtsc,
/* 0x32 */ x86emuOp2_illegal_op,
/* 0x33 */ x86emuOp2_illegal_op,
/* 0x34 */ x86emuOp2_illegal_op,