Operations:

Format

Syntax:

Operation:

Operands:

Architecture revision

Opcode

1

satsub.hRd, Rx, Ry 

temp = ZE(Rx[15:0]) - ZE(Ry[15:0]) ;
if (Rx[15] AND ~Ry[15] AND ~temp[15]) OR (~Rx[15] AND Ry[15] AND temp[15]) then
     if Rx[15]==0 then
           Rd = 0x00007fff;
     else
           Rd = 0xffff8000;
else
      Rd = SE(temp[15:0]);
 
{d, s} ∈ {0, 1, …, 15}

Rev1+

111

Rx

00000

Ry

000000111100

Rd

3

4

5

4

12

4

Description

Performs a subtraction of the specified halfwords and stores the result in destination register. The result is saturated if it overflows the range representable with 16 bits. If saturation occurs, the Q flag is set.

Status Flags:

Q:

Q = (Rx[15] AND ~Ry[15] AND ~temp[15]) OR (~Rx[15] AND Ry[15] AND temp[15]) OR Q

V:

V = (Rx[15] AND ~Ry[15] AND ~temp[15]) OR (~Rx[15] AND Ry[15] AND temp[15])

N:

N = Rd[15]

Z:

Z = (Rd[15:0] == 0)

C:

C = 0