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100

101

Core Control Registers

SC140 DSP Core Reference Manual 3-3

LF2

Bit 29

Loop Flag 2 — When set, indicates that

hardware loop #3 is enabled. At the start

of an ISR, the SR (including the LF2 bit)

is pushed onto the software stack and

the LF2 bit is cleared.

This bit is cleared at core reset.

0 = Hardware loop #3 not enabled

1 = Hardware loop #3 enabled

LF1

Bit 28

Loop Flag 1 — When set, indicates that

hardware loop #2 is enabled. At the start

of an ISR, the SR (including the LF1 bit)

is pushed onto the software stack and

the LF1 bit is cleared.

This bit is cleared at core reset.

0 = Hardware loop #2 not enabled

1 = Hardware loop #2 enabled

LF0

Bit 27

Loop Flag 0 — When set, indicates that

hardware loop #1 is enabled. At the start

of an ISR, the SR (including the LF0 bit)

is pushed onto the software stack and

the LF0 bit is cleared.

This bit is cleared at core reset.

0 = Hardware loop #1 not enabled

1 = Hardware loop #1 enabled

Bits

26–24

Reserved

I2–I0

Bits

23–21

Interrupt Mask Bits — Reflect the

current interrupt priority level (IPL) of the

core. Only non-maskable interrupts or

interrupts with an IPL higher than the

current interrupt mask value can

interrupt the core. The current IPL of the

core can be changed under software

control.

At the start of an ISR, the SR (including

the interrupt mask bits) is pushed onto

the software stack. The interrupt mask

bits are changed to the IPL of the

interrupt being serviced.

The interrupt mask bits are set at core

reset.

For a detailed description of interrupt

service, refer to Section 5.8, “Exception

Processing,” on page 5-46.

An IPL0 exception is always masked.

Table 3-1. Status Register Description (Continued)

Name Description Settings

I2 I1 I0

Exceptions

Permitted

Exceptions

Masked

000IPL 1–7 IPL 0

0 0 1 IPL 2–7 IPL 0–1

0 1 0 IPL 3–7 IPL 0–2

0 1 1 IPL 4–7 IPL 0–3

1 0 0 IPL 5–7 IPL 0–4

1 0 1 IPL 6–7 IPL 0–5

1 1 0 IPL 7 IPL 0–6

1 1 1 NMI IPL 0–7

1 2 ... 98 99 100 101 102 103 104 105 106 107 108 ... 759 760

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