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SBC (Super FX): Difference between revisions
From SnesLab
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==== Example ==== | |||
Let: | |||
S<sub>reg</sub> : R<sub>4</sub> | |||
D<sub>reg</sub> : R<sub>6</sub> | |||
R<sub>4</sub> = 5682h | |||
R<sub>5</sub> = 3609h | |||
CY = 1 | |||
After executing SBC R<sub>5</sub>: | |||
R<sub>6</sub> = 2079h | |||
CY = 0 | |||
=== See Also === | === See Also === | ||
Revision as of 00:30, 10 July 2024
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | ROM Speed | RAM Speed | Cache Speed | ||
| 3D6n | 2 bytes | 6 cycles | 6 cycles | 2 cycle | |||
| Flags Affected | ||||||||
|---|---|---|---|---|---|---|---|---|
| B | ALT1 | ALT2 | O/V | S | CY | Z | ||
| 0 | 0 | 0 | ||||||
SBC (SuBtract with Carry) is a Super FX instruction that performs a subtraction with regards to the carry flag. Unlike ADD (Super FX), ADC (Super FX) and SUB (Super FX), this one can only be used with registers, not with constant values since since the ALT3 version of SUB is a CMP (Super FX) instead.
The source and destination registers should be specified in advance using WITH, FROM, or TO. Otherwise, R0 serves as the default.
Syntax
SBC Rn
Example
Let:
Sreg : R4 Dreg : R6 R4 = 5682h R5 = 3609h CY = 1
After executing SBC R5:
R6 = 2079h CY = 0
See Also
Reference
- 9.78 on page 2-9-108 of Book II of the official Super Nintendo development manual