34 lines
1.3 KiB
Go
34 lines
1.3 KiB
Go
package z80
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import "testing"
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// BIT n,(IX+d)/(IY+d): X/Y must come from MEMPTR high byte, cycles 20 for BIT on indexed (no write-back).
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func TestBIT_IXIY_Displacement_FlagsAndTiming(t *testing.T) {
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// IX case
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cpu, mem, _ := testCPU()
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cpu.IX = 0x3000
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mem.WriteByte(0x3005, 0x80) // bit 7 set
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loadProgram(cpu, mem, 0x0000, 0xDD, 0xCB, 0x05, 0x7E) // BIT 7,(IX+5)
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c := mustStep(t, cpu)
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// Z=0, S=1 for bit7 set
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assertFlag(t, cpu, FLAG_Z, false, "BIT Z")
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assertFlag(t, cpu, FLAG_S, true, "BIT S for bit7")
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// X/Y from MEMPTR high byte
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memptrHi := byte(cpu.MEMPTR >> 8)
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assertFlag(t, cpu, FLAG_X, (memptrHi&FLAG_X) != 0, "X from MEMPTR high (IX)")
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assertFlag(t, cpu, FLAG_Y, (memptrHi&FLAG_Y) != 0, "Y from MEMPTR high (IX)")
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assertEq(t, c, 20, "cycles for DDCB BIT (IX+d) should be 20")
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// IY case
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cpu, mem, _ = testCPU()
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cpu.IY = 0x4000
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mem.WriteByte(0x4002, 0x01) // bit 0 set
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loadProgram(cpu, mem, 0x0000, 0xFD, 0xCB, 0x02, 0x46) // BIT 0,(IY+2)
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c = mustStep(t, cpu)
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assertFlag(t, cpu, FLAG_Z, false, "BIT Z (IY)")
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memptrHi = byte(cpu.MEMPTR >> 8)
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assertFlag(t, cpu, FLAG_X, (memptrHi&FLAG_X) != 0, "X from MEMPTR high (IY)")
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assertFlag(t, cpu, FLAG_Y, (memptrHi&FLAG_Y) != 0, "Y from MEMPTR high (IY)")
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assertEq(t, c, 20, "cycles for FDCB BIT (IY+d) should be 20")
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}
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