Propeller Manual

SUMC – Assembly Language Reference
SUMC
Instruction: Sum a signed value with another whose sign is inverted depending on C.
SUMC SValue1, 〈#〉 SValue2
Result: Sum of signed SValue1 and ±SValue2 is stored in SValue1.
•
SValue1 (d-field) is the register containing the value to sum with either –SValue2 or
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 sign-affected by C and
summed into SValue1.
Opcode Table:
–INSTR– ZCRI –CON– –DEST– –SRC– Z Result C Result Result Clocks
100100 001i 1111 ddddddddd sssssssss
D ± S = 0 Signed Overflow Written 4
Concise Truth Table:
In Out
Destination Source Z C Effects Destination Z C
$0000_0001; 1 $0000_0001; 1 - 0
wz wc
$0000_0002; 2 0 0
$0000_0001; 1 $0000_0001; 1 - 1
wz wc
$0000_0000; 0 1 0
$0000_0001; 1 $FFFF_FFFF; -1 - 0
wz wc
$0000_0000; 0 1 0
$FFFF_FFFF; -1 $FFFF_FFFF; -1 - 0
wz wc
$FFFF_FFFE; -2 0 0
$FFFF_FFFF; -1 $FFFF_FFFF; -1 - 1
wz wc
$0000_0000; 0 1 0
$FFFF_FFFF; -1 $0000_0001; 1 - 0
wz wc
$0000_0000; 0 1 0
$8000_0000; -2,147,483,648 $0000_0001; 1 - 0
wz wc
$8000_0001; -2,147,483,647 0 0
$8000_0000; -2,147,483,648 $0000_0001; 1 - 1
wz wc
$7FFF_FFFF; 2,147,483,647 0 1
$8000_0000; -2,147,483,648 $FFFF_FFFF; -1 - 0
wz wc
$7FFF_FFFF; 2,147,483,647 0 1
$7FFF_FFFF; 2,147,483,647 $FFFF_FFFF; -1 - 0
wz wc
$7FFF_FFFE; 2,147,483,646 0 0
$7FFF_FFFF; 2,147,483,647 $FFFF_FFFF; -1 - 1
wz wc
$8000_0000; -2,147,483,648 0 1
$7FFF_FFFF; 2,147,483,647 $0000_0001; 1 - 0
wz wc
$8000_0000; -2,147,483,648 0 1
Explanation
SUMC (Sum with C-affected sign) adds the signed value of SValue1 to –SValue2 (if C = 1) or
to SValue2 (if C = 0) 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.
Page 356 · Propeller Manual v1.1