Propeller Manual

3: Assembly Language Reference – ADDS
ADDS
Instruction: Add two signed values.
ADDS SValue1, 〈#〉 SValue2
Result: Sum of signed SValue1 and signed SValue2 is stored in SValue1.
•
SValue1 (d-field) is the register containing the value to add to SValue2 and is the
destination in which to write the result.
•
SValue2 (s-field) is a register or a 9-bit literal whose value is added into SValue1.
Opcode Table:
–INSTR– ZCRI –CON– –DEST– –SRC– Z Result C Result Result Clocks
110100 001i 1111 ddddddddd sssssssss
D + S = 0 Signed Overflow Written 4
Concise Truth Table:
In Out
Destination Source Z C Effects Destination Z C
$FFFF_FFFF; -1 $0000_0001; 1 - -
wz wc
$0000_0000; 0 1 0
$FFFF_FFFF; -1 $0000_0002; 2 - -
wz wc
$0000_0001; 1 0 0
$0000_0001; 1 $FFFF_FFFF; -1 - -
wz wc
$0000_0000; 0 1 0
$0000_0001; 1 $FFFF_FFFE; -2 - -
wz wc
$FFFF_FFFF; -1 0 0
$7FFF_FFFE; 2,147,483,646 $0000_0001; 1 - -
wz wc
$7FFF_FFFF; 2,147,483,647 0 0
$7FFF_FFFE; 2,147,483,646 $0000_0002; 2 - -
wz wc
$8000_0000; -2,147,483,648 0 1
$8000_0001; -2,147,483,647 $FFFF_FFFF; -1 - -
wz wc
$8000_0000; -2,147,483,648 0 0
$8000_0001; -2,147,483,647 $FFFF_FFFE; -2 - -
wz wc
$7FFF_FFFF; 2,147,483,647 0 1
Explanation
ADDS sums the two signed values of SValue1 and SValue2 together and stores the result into
the SValue1 register.
If the
WZ effect is specified, the Z flag is set (1) if SValue1 + SValue2 equals zero. If the WC
effect is specified, the C flag is set (1) if the summation resulted in a signed overflow. The
result is written to SValue1 unless the
NR effect is specified.
To add signed, multi-long values, use
ADD, possibly ADDX, and finally ADDSX. See ADDSX on
page 262 for more information.
Propeller Manual v1.1 · Page 261