B Flag (Super FX): Difference between revisions

Latest revision as of 23:06, 21 July 2024

The B Flag is on the Super FX, and is set when WITH runs. It is bit 4 of SFR.

These instructions change their behaviour on the B flag:

TO R_n' as MOVE R_n,R_n'
FROM R_n' as MOVES R_n,R_n'

For both of them, the R_n is set by the preceeeding WITH R_n.

Many instructions clear the B flag, including:

ADC R_n
ADC #n
ADD R_n
ADD #n
AND R_n
AND #n
ASR
BIC R_n
BIC #n
CACHE
CMODE
CMP R_n
COLOR
DEC R_n
DIV2
FMULT
GETB
GETBH
GETBL
GETBS
GETC
HIB
IBT R_n, #pp
INC R_n
IWT R_n, #xx
JMP R_n
LDB (R_m)
LDW (R_m)
LEA R_n, xx
LINK #n
LJMP R_n
LM R_n, (xx)
LMS R_n, (yy)
LMULT
LOB
LOOP
LSR
MERGE
MOVE R_n, R_n'
MOVES R_n, R_n'
MULT R_n
MULT #n
NOP
NOT
OR R_n
OR #n
PLOT
RAMB
ROL
ROMB
ROR
RPIX
SBC R_n
SBK
SEX
SM (xx), R_n
SMS (yy), R_n
STB (R_m)
STOP
STW (R_m)
SUB R_n
SUB #n
SWAP
UMULT R_n
and presumably UMULT #n too

References

page 2-9-2 of Book II of the official Super Nintendo development manual
page 2-4-4 of Book II, lbid.

@@ Line 1: / Line 1: @@
-The '''B flag''' is on the [[Super FX]], and is set when [[WITH]] runs.
+The '''B Flag''' is on the [[Super FX]], and is set when [[WITH]] runs.  It is bit 4 of SFR.
+These instructions change their behaviour on the B flag:
+*  [[TO]] R<sub>n'</sub> as [[MOVE]] R<sub>n</sub>,R<sub>n'</sub>
+*  [[FROM]] R<sub>n'</sub> as [[MOVES]] R<sub>n</sub>,R<sub>n'</sub>
+For both of them, the R<sub>n</sub> is set by the preceeeding WITH R<sub>n</sub>.
+Many instructions clear the B flag, including:
+*	[[GSU/ADC|ADC]] R<sub>n</sub>
+*	[[GSU/ADC|ADC]] #n
+*	[[ADD]] R<sub>n</sub>
+*	[[ADD]] #n
+*	[[GSU/AND|AND]] R<sub>n</sub>
+*	[[GSU/AND|AND]] #n
+*	[[ASR]]
+*	[[BIC]] R<sub>n</sub>
+*	[[BIC]] #n
+*	[[CACHE]]
+*	[[CMODE]]
+*	[[GSU/CMP|CMP]] R<sub>n</sub>
+*	[[COLOR]]
+*	[[GSU/DEC|DEC]] R<sub>n</sub>
+*	[[DIV2]]
+*	[[FMULT]]
+*	[[GETB]]
+*	[[GETBH]]
+*	[[GETBL]]
+*	[[GETBS]]
+*	[[GETC]]
+*	[[HIB]]
+*	[[IBT]] R<sub>n</sub>, #pp
+*	[[GSU/INC|INC]] R<sub>n</sub>
+*	[[IWT]] R<sub>n</sub>, #xx
+*	[[GSU/JMP|JMP]] R<sub>n</sub>
+*	[[LDB]] (R<sub>m</sub>)
+*	[[LDW]] (R<sub>m</sub>)
+*	[[LEA]] R<sub>n</sub>, xx
+*	[[LINK]] #n
+*	[[LJMP]] R<sub>n</sub>
+*	[[LM]] R<sub>n</sub>, (xx)
+*	[[LMS]] R<sub>n</sub>, (yy)
+*	[[LMULT]]
+*	[[LOB]]
+*	[[LOOP]]
+*	[[GSU/LSR|LSR]]
+*	[[MERGE]]
+*	[[MOVE]] R<sub>n</sub>, R<sub>n</sub>'
+*	[[MOVES]] R<sub>n</sub>, R<sub>n</sub>'
+*	[[MULT]] R<sub>n</sub>
+*	[[MULT]] #n
+*	[[GSU/NOP|NOP]]
+*	[[NOT]]
+*	[[OR]] R<sub>n</sub>
+*	[[OR]] #n
+*	[[PLOT]]
+*	[[RAMB]]
+*	[[GSU/ROL|ROL]]
+*	[[ROMB]]
+*	[[GSU/ROR|ROR]]
+*	[[RPIX]]
+*	[[GSU/SBC|SBC]] R<sub>n</sub>
+*	[[SBK]]
+*	[[SEX]]
+*	[[SM]] (xx), R<sub>n</sub>
+*	[[SMS]] (yy), R<sub>n</sub>
+*	[[STB]] (R<sub>m</sub>)
+*	[[STOP]]
+*	[[STW]] (R<sub>m</sub>)
+*	[[SUB]] R<sub>n</sub>
+*	[[SUB]] #n
+*	[[SWAP]]
+*	[[UMULT]] R<sub>n</sub>
+*	and presumably UMULT #n too
+=== See Also ===
+* [[Dither Flag]]
+* [[Break Flag]]
+* [[ALT1]]
+* [[ALT2]]
+* [[ALT0]]
+=== References ===
+* [https://archive.org/details/SNESDevManual/book2/page/n158 page 2-9-2 of Book II] of the official Super Nintendo development manual
+* [https://archive.org/details/SNESDevManual/book2/page/n110 page 2-4-4 of Book II], lbid.
 [[Category:Flags]]
 [[Category:Super FX]]
+[[Category:ASM]]