Computer Hardware User's Guide

SUBB3 Subtract Integer With Borrow, 3-Operand
13-224
Syntax SUBB3 src2, src1, dst
Operation src1 – src2 – C → dst
Operands src1 3-operand addressing modes (T):
0 0 register (R n 1, 0 ≤ n 1 ≤ 27)
0 1 indirect (
disp = 0, 1, IR0, IR1)
1 0 register (R n 1, 0 ≤ n 1 ≤ 27)
1 1 indirect ( disp = 0, 1, IR0, IR1)
src2 3-operand addressing modes (T):
0 0 register (R n 2, 0 ≤ n 2 ≤ 27)
0 1 register (R n 2, 0 ≤ n 2 ≤ 27)
1 0 indirect (
disp = 0, 1, IR0, IR1)
1 1 indirect ( disp = 0, 1, IR0, IR1)
dst register (R n , 0 ≤ n ≤ 27)
Opcode
31 24 23 16 8 7 015
001 00 0
1 01
dst
T
src 1 src 2
Description The difference among the src1 and src2 operands and the C flag is loaded into
the dst register. The src1, src2, and dst operands are assumed to be signed
integers.
Cycles 1
Status Bits These condition flags are modified only if the destination register is R7–R0.
LUF Unaffected
LV 1 if an integer overflow occurs; unchanged otherwise
UF 0
N 1 if a negative result is generated; 0 otherwise
Z 1 if a 0 result is generated; 0 otherwise
V 1 if an integer overflow occurs; 0 otherwise
C 1 if a borrow occurs; 0 otherwise
OVM Operation is affected by OVM bit value.Mode Bit