Subtract X-Y/Subtract X-Y With Borrow - Analog Devices adsp-2100 Manual

SUBTRACT X-Y / SUBTRACT X-Y with BORROW
Syntax:
[ IF cond ]
Permissible xops
AX0 MR2
AX1 MR1
AR MR0
SR1
SR0
Permissible constants (ADSP-217x, ADSP-218x, ADSP-21msp58/59 only)
0, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32767
–2, –3, –5, –9, –17, –33, –65, –129, –257, –513, –1025, –2049, –4097, –8193, –16385, –
32768
Example:
IF GE AR = AX0 – AY0;
Description:
Test the optional condition and, if true, then perform the
specified subtraction. If the condition is not true then perform a no-operation.
Omitting the condition performs the subtraction unconditionally. The
subtraction operation subtracts the second source operand from the first
source operand, and optionally adds the ALU Carry bit (AC) minus 1
(H#0001), and stores the result in the destination register. The (C–1) quantity
effectively implements a borrow capability for multiprecision subtractions.
The operands are contained in the data registers or constant specified in the
instruction.
The xop – constant operation is only available on the ADSP-217x, ADSP-218x,
and ADSP-21msp58/59 processors and may not be used in multifunction
instructions.
Status Generated:
ASTAT: 7 6
SS MV AQ AS
- -
AZ Set if the result equals zero. Cleared otherwise.
AN Set if the result is negative. Cleared otherwise.
AV Set if an arithmetic overflow occurs. Cleared otherwise.
AR =
AF
Permissible yops
AY0
AY1
AF
5 4 3
AC AV AN AZ
- - *
(instruction continues on next page)
xop – yop
– yop + C–1
+ C–1
– constant
– constant + C–1
Permissible conds (see Table 15.9)
EQ LE
NE NEG
GT POS
GE AV
LT NOT AV NOT CE
2 1 0
* * *
ALU
;
AC
NOT AC
MV
NOT MV
15
15 – 23