5.55. Single Precision Integer Add


Addr
Mode  Mnemonic          Format/Opcode
                           8      4      4
                        ----------------------
R     AR    RA,RB       |  A1  |  RA  |  RB  |
                        ----------------------
                          4   2   2      8        12<=BR<=15
                        ----------------------  
B     AB    BR,DSPL     | 1 | 0 | BR' | DSPL |    BR'=BR-12
                        ----------------------    RA=R2
                          4   2   2     4   4     12<=BR<=15
                        ------------------------  
BX    ABX   BR,RX       | 4 | 0 | BR' | 4 | RX |  BR'=BR-12
                        ------------------------  RA=R2
                           8      4      4
                        -----------------------
ISP   AISP  RA,N        |  A2  |  RA  |  N-1  |   1<N<16
                        -----------------------
                           8      4      4           16
D     A     RA,ADDR     --------------------------------------
DX    A     RA,ADDR,RX  |  A0  |  RA  |  RX  |  |    ADDR    |
                        --------------------------------------
                           8      4      4           16
                        --------------------------------------
IM    AIM   RA,DATA     |  4A  |  RA  |  1   |  |    DATA    |
                        --------------------------------------

Description. The Derived Operand (DO) is added to the contents of the RA register. The result (a 2's complement sum) is stored in register RA. The condition status (CS) is set based on the result in register RA and carry. A fixed point overflow occurs if both operands are of the same sign and the sum is of opposite sign.

Register Transfer Description.

(RA)2 <-- (RA)1 + DO;
PI4 <-- 1, if (RA0) 1 = DO0 and (RA0) 1  /= (RA0)2
(CS) <-- 0010  if  carry = 0 and (RA) = 0;
(CS) <-- 0001  if  carry = 0 and (RA) < 0;
(CS) <-- 0100  if  carry = 0 and (RA) >= 0;
(CS) <-- 1010  if  carry = 1 and (RA) = 0;
(CS) <-- 1001  if  carry = 1 and (RA) < 0;
(CS) <-- 1100  if  carry = 1 and (RA) >= 0;

Registers Affected. RA, CS, PI