1.13 CPU STATUS Register

Note:

This bit may be read or cleared (not set). Clearing this bit will clear SA and SB irrespective of the value simultaneously written to SA and/or SB.
IPL[2:0] become read only bits if NSTDIS(INTCON1[15])=1 (nesting disabled). .

Legend: C = Clearable bit

Name:

SR


Bit	31	30	29	28	27	26	25	24

Access
Reset


Bit	23	22	21	20	19	18	17	16
	VF					CTX[2:0]
Access	R					R	R	R
Reset	0					0	0	0


Bit	15	14	13	12	11	10	9	8
	OA	OB	SA	SB	OAB	SAB		IPL3
Access	R/W	R/W	R/W	R/W	R	R/C		R/C
Reset	0	0	0	0	0	0		0


Bit	7	6	5	4	3	2	1	0
	IPL[2:0]			RA	N	OV	Z	C
Access	R/W	R/W	R/W	R	R/W	R/W	R/W	R/W
Reset	0	0	0	0	0	0	0	0

Bit 23 – VF Vector (Fetch) Fail Status

Value	Description
`1`	Indicates to the bus error handler that the source of the bus error is a vector fetch. The vector data read will be substituted with the contents of the Vector Fail Address (VFA) SFR.
`0`	Indicates to the bus error handler that the source of the bus error is not a vector fetch.

Bits 18:16 – CTX[2:0] Current (W register) Context Identifier

Identifies which W register context is currently in use by the CPU

Value	Description
`111`	Context 7 is currently in use
`110`	Context 6 is currently in use
`101`	Context 5 is currently in use
`100`	Context 4 is currently in use
`011`	Context 3 is currently in use
`010`	Context 2 is currently in use
`001`	Context 1 is currently in use
`000`	Context 0 is currently in use

Bit 15 – OA Accumulator A Fractional Overflow Status

Value	Description
`1`	Accumulator A fractional overflow has occurred (its contents can no longer be represented as a 1.31 fractional value)
`0`	Accumulator A not overflowed

Bit 14 – OB Accumulator B Fractional Overflow Status

Value	Description
`1`	Accumulator A fractional overflow has occurred (its contents can no longer be represented as a 1.31 fractional value)
`0`	Accumulator A not overflowed

Bit 13 – SA Accumulator A Saturation/Sign Overflow ‘Sticky’ Status

Value	Description
`1`	Accumulator A is saturated or has been saturated at some time, or has overflowed into bit 71 (if saturation is disabled)
`0`	Accumulator A is not saturated or has not overflowed into bit 71 (if saturation is disabled)

Bit 12 – SB Accumulator B Saturation/Sign Overflow ‘Sticky’ Status

Value	Description
`1`	Accumulator B is saturated or has been saturated at some time, or has overflowed into bit 71 (if saturation is disabled)
`0`	Accumulator B is not saturated or has not overflowed into bit 71 (if saturation is disabled)

Bit 11 – OAB OA || OB Combined Accumulator Fractional Overflow Status

Value	Description
`1`	Accumulators A or B fractional overflow has occurred (one or both of their contents can no longer be represented as a 1.31 fractional value)
`0`	Neither Accumulators A nor B have overflowed

Bit 10 – SAB SA || SB Combined Accumulator ‘Sticky’ Status⁽¹⁾

Value	Description
`1`	Accumulators A or B are saturated or have been saturated at some time, or have overflowed into bit 71 (if saturation is disabled)
`0`	Neither Accumulator A nor B are saturated or have overflowed into bit 71 (if saturation is disabled)

Bit 8 – IPL3 MSb (Most Significant bit) of CPU Priority Level Nibble

Value	Description
`1`	CPU Priority ≥ 8 (trap exception underway)
`0`	CPU Priority < 8 (no trap exception underway)

Bits 7:5 – IPL[2:0] CPU Interrupt Priority Level Status⁽²⁾

Value	Description
`111`	All interrupts disabled
`110`	Level 7 interrupts enabled
`101`	Level 6 and 7 interrupts enabled
`100`	Level 5 through 7 interrupts enabled
`011`	Level 4 through 7 interrupts enabled
`010`	Level 3 through 7 interrupts enabled
`001`	Level 2 through 7 interrupts enabled
`000`	Level 1 through 7 interrupts enabled

Bit 4 – RA `REPEAT` Loop Active

Value	Description
`1`	`REPEAT` loop in progress
`0`	`REPEAT` loop not in progress

Bit 3 – N MCU ALU Negative

Value	Description
`1`	Result was negative
`0`	Result was non-negative (zero or positive)

Bit 2 – OV MCU ALU Overflow

This bit is used for signed arithmetic (2’s complement). It indicates an overflow of the magnitude that causes the Sign bit to change state.

Value	Description
`1`	Overflow occurred for signed arithmetic (in this arithmetic operation)
`0`	No overflow occurred

Bit 1 – Z MCU ALU ‘Sticky’ Zero

Value	Description
`1`	An operation which effects the Z bit has set it at some time in the past
`0`	The most recent operation which effects the Z bit has cleared it (i.e., a non-zero result)

Bit 0 – C MCU ALU Carry/Borrow

Value	Description
`1`	A carry-out from the MSb of the result occurred
`0`	No carry-out from the MSb of the result occurred

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