ADC (SPC700): Difference between revisions

Latest revision as of 08:53, 19 September 2024


Basic Info
Addressing Mode	Opcode	Length	Speed
Immediate	88	2 bytes	2 cycles
Implied (type 1)	86	1 byte	3 cycles
Direct Page	84	2 bytes	3 cycles
Direct Page Indexed by X	94	2 bytes	3 cycles
Absolute	85	3 bytes	4 cycles
Absolute Indexed by X	95	3 bytes	5 cycles
Absolute Indexed by Y	96	3 bytes	5 cycles
Direct Page Indexed by X	87	2 bytes	6 cycles
Direct Page Indirect Indexed by Y	97	2 bytes	6 cycles
Implied (type 1)	99	1 byte	5 cycles
Direct Page	89	3 bytes	6 cycles
Direct Page Immediate	98	3 bytes	5 cycles


Flags Affected
N	V	P	B	H	I	Z	C
N	V	.	.	H	.	Z	C

ADC (Add with Carry) is an SPC700 instruction that adds the value of the two operands together (along with the carry flag) and stores the sum in the left operand. Often, the left operand is the accumulator.

The operands are stored in the instruction stream in the opposite order they appear in the assembler source. In the assembler source, the operand on the right is the source and the operand on the left is the destination.

Syntax

ADC A, #imm
ADC A, (X)
ADC A, dp
ADC A, dp+X
ADC A, !abs
ADC A, !abs+X
ADC A, !abs+Y
ADC A, [dp+X]
ADC A, [dp]+Y
ADC (X), (Y)
ADC dp<d>, dp<s>
ADC dp, #imm

Unlike the 65c816, the SPC700 has no decimal mode, so the addition is always done in binary/hexadecimal. Use DAA after adding BCD-encoded data to repair it back to BCD.

External Links

Official Super Nintendo development manual on ADC: Table C-7 in Appendix C-5 of Book I
anomie: https://github.com/yupferris/TasmShiz/blob/8fabc9764c33a7ae2520a76d80ed7220bb939f12/spc700.txt#L304

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 |[[Carry Flag|C]]
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 ADC dp, #imm
 </pre>
+Unlike the [[65c816]], the SPC700 has no [[decimal mode]], so the addition is always done in binary/hexadecimal.  Use [[DAA]] after adding [[BCD]]-encoded data to repair it back to BCD.
 === See Also ===