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Rewrite SBC test

This commit is contained in:
Peter Evans 2018-05-06 20:06:51 -05:00
parent ab022c5d58
commit 21623257ef

View File

@ -376,25 +376,69 @@ Test(mos6502_arith, iny)
cr_assert_eq(cpu->P & MOS_ZERO, MOS_ZERO);
}
/*
* SBC has a lot of similarities with the spirit of ADC; it is
* deceptively simple, doing the following:
*
* A = A - DATA if C = 1
* A = A - DATA - 1 if C = 0
*
* Z = 1 if RESULT = 0
* V = 1 if (A ^ DATA) has BIT 7 high AND (A ^ RESULT) has BIT 7 high
* N = 1 if RESULT has BIT 7 high
* C = 1 if (16-BIT) RESULT < 0
*/
Test(mos6502_arith, sbc)
{
cpu->A = 5;
mos6502_handle_sbc(cpu, 3);
cr_assert_eq(cpu->A, 2);
vm_8bit start = 90,
main = 60,
ztest = start,
vtest = 0x80,
ntest = 0xff;
cpu->A = 0x3;
mos6502_handle_sbc(cpu, 5);
cr_assert_eq(cpu->A, (vm_8bit)(0x3 - 0x5));
// Test with and without carry
cpu->P |= MOS_CARRY;
cpu->A = start;
mos6502_handle_sbc(cpu, main);
cr_assert_eq(cpu->A, start - main);
cpu->P &= ~MOS_CARRY;
cpu->A = 16;
mos6502_handle_sbc(cpu, 8);
cr_assert_eq(cpu->A, 7);
cpu->A = start;
mos6502_handle_sbc(cpu, main);
cr_assert_eq(cpu->A, start - main - 1);
cr_assert_eq(cpu->P & MOS_ZERO, 0);
cr_assert_eq(cpu->P & MOS_NEGATIVE, 0);
cr_assert_eq(cpu->P & MOS_OVERFLOW, 0);
cr_assert_eq(cpu->P & MOS_CARRY, MOS_CARRY);
cpu->P |= MOS_DECIMAL;
cpu->A = 0x12;
mos6502_handle_sbc(cpu, 0x3);
cr_assert_eq(cpu->A, 0x9);
cpu->A = start;
cpu->P |= MOS_CARRY;
mos6502_handle_sbc(cpu, ztest);
cr_assert_eq(cpu->A, 0);
cr_assert_eq(cpu->P & MOS_ZERO, MOS_ZERO);
cr_assert_eq(cpu->P & MOS_NEGATIVE, 0);
cr_assert_eq(cpu->P & MOS_OVERFLOW, 0);
cr_assert_eq(cpu->P & MOS_CARRY, MOS_CARRY);
cpu->A = start;
cpu->P |= MOS_CARRY;
mos6502_handle_sbc(cpu, vtest);
cr_assert_eq(cpu->A, (vm_8bit)(start - vtest));
cr_assert_eq(cpu->P & MOS_ZERO, 0);
cr_assert_eq(cpu->P & MOS_NEGATIVE, MOS_NEGATIVE);
cr_assert_eq(cpu->P & MOS_OVERFLOW, MOS_OVERFLOW);
cr_assert_eq(cpu->P & MOS_CARRY, 0);
cpu->A = start;
cpu->P |= MOS_CARRY;
mos6502_handle_sbc(cpu, ntest);
cr_assert_eq(cpu->A, (vm_8bit)(start - ntest));
cr_assert_eq(cpu->P & MOS_ZERO, 0);
cr_assert_eq(cpu->P & MOS_NEGATIVE, MOS_NEGATIVE);
cr_assert_eq(cpu->P & MOS_OVERFLOW, 0);
cr_assert_eq(cpu->P & MOS_CARRY, 0);
// FIXME: add a decimal test
}
Test(mos6502_arith, sbc_dec)