dsp56000 Freescale Semiconductor, Inc, dsp56000 Datasheet - Page 88

• Manufacturer Part Number: dsp56000
• Description: 24-bit Digital Signal Processor Family Manual
• Manufacturer: Freescale Semiconductor, Inc

5.4.2.9
The interrupt mask bits, I1 and I0, reflect the current IPL of the processor and indicate
the IPL needed for an interrupt source to interrupt the processor. The current IPL of the
processor can be changed under software control. The interrupt mask bits are set during
hardware reset but not during software reset.
5.4.2.10
The scaling mode bits, S1 and S0, specify the scaling to be performed in the data ALU
shifter/limiter, and also specify the rounding position in the data ALU multiply-accumula-
5 - 12
Scaling Mode (Bits 10 and 11)
Interrupt Masks (Bits 8 and 9)
If
then S = (A46 XOR A45) OR (B46 XOR B45)
If
then S = (A47 XOR A46) OR (B47 XOR B46)
If
then S = (A45 XOR A44) OR (B45 XOR B44)
If
then the S flag is undefined.
where Ai and Bi means bit i in accumulator A or B.
I1
0
0
1
1
S1=0 and S0=0 (no scaling)
S1=0 and S0=1 (scale down)
S1=1 and S0=0 (scale up)
S1=1 and S0=1 (reserved)
Freescale Semiconductor, Inc.
I0
0
1
0
1
For More Information On This Product,
IPL 0,1,2,3
IPL 1,2,3
IPL 2,3
IPL 3
Exceptions Permitted
PROGRAM CONTROL UNIT
PROGRAMMING MODEL
Go to: www.freescale.com
None
IPL 0
IPL 0,1
IPL 0,1,2
Exceptions Masked
MOTOROLA