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i386: x87 stack top set to 0 when entering mmx state, generate #NM only from TS bit

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Mmx opcodes generate #NM only when TS is set, EM bit generates #UD
This commit is contained in:
yz70s 2024-07-13 10:22:26 +02:00
parent db5d0f4f4b
commit 71b9d2f072
1 changed files with 8 additions and 4 deletions
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12
src/devices/cpu/i386/pentops.hxx
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@ -7,12 +7,12 @@ extern flag float64_is_nan( float64 a ); // since its not defined in softfloat.h
bool i386_device::MMXPROLOG()
{
if (m_cr[0] & (CR0_TS | CR0_EM))
if (m_cr[0] & CR0_TS)
{
i386_trap(FAULT_NM, 0, 0);
return true;
}
//m_x87_sw &= ~(X87_SW_TOP_MASK << X87_SW_TOP_SHIFT); // top = 0
x87_set_stack_top(0);
m_x87_tw = 0; // tag word = 0
return false;
}
@ -1913,13 +1913,17 @@ void i386_device::mmx_paddd_r64_rm64() // Opcode 0f fe
void i386_device::mmx_emms() // Opcode 0f 77
{
if (m_cr[0] & (CR0_TS | CR0_EM))
if (m_cr[0] & CR0_TS)
{
i386_trap(FAULT_NM, 0, 0);
return;
}
if (m_cr[0] & CR0_EM)
{
i386_trap(FAULT_UD, 0, 0);
return;
}
m_x87_tw = 0xffff; // tag word = 0xffff
// TODO
CYCLES(1); // TODO: correct cycle count
}