Analog Devices ADSP-21261 SHARC Hardware Reference Manual page 634

Core Registers
Table A-4. ASTATx and ASTATy Register Bit Descriptions
Bit Name
0 AZ
1 AV
2 AN
3 AC
4 AS
A-12
Description
ALU Zero/Floating-Point Underflow. Indicates if the last ALU operation's
result was zero (if set, = 1) or non-zero (if cleared, = 0). The ALU updates
AZ for all fixed-point and floating-point ALU operations. AZ can also
indicate a floating-point underflow. During an ALU underflow (indicated
by a set (= 1) AUS bit in the STKYx/y register), the processor sets AZ if the
floating-point result is smaller than can be represented in the output for-
mat.
ALU Overflow. Indicates if the last ALU operation's result overflowed (if
set, = 1) or did not overflow (if cleared, = 0). The ALU updates AV for all
fixed-point and floating-point ALU operations. For fixed-point results, the
processor sets AV and the AOS bit in the STKYx/y register when the XOR
of the two most significant bits (MSBs) is a 1. For floating-point results,
the processor sets AV and the AVS bit in the STKYx/y register when the
rounded result overflows (unbiased exponent > 127).
ALU Negative. Indicates if the last ALU operation's result was negative (if
set, = 1) or positive (if cleared, = 0). The ALU updates AN for all
fixed-point and floating-point ALU operations.
ALU Fixed-Point Carry. Indicates if the last ALU operation had a carry
out of the MSB of the result (if set, = 1) or had no carry (if cleared, = 0).
The ALU updates AC for all fixed-point operations. The processor clears
AC during the fixed-point logic operations: PASS, MIN, MAX, COMP,
ABS, and CLIP. The ALU reads the AC flag for the fixed-point accumulate
operations: Addition with Carry and Fixed-point Subtraction with Carry.
ALU X-Input Sign (for ABS and MANT). Indicates if the last ALU ABS
or MANT operation's input was negative (if set, = 1) or positive (if cleared,
= 0). The ALU updates AS only for fixed- and floating-point ABS and
MANT operations. The ALU clears AS for all operations other than ABS
and MANT.
ADSP-2126x SHARC Processor Hardware Reference