Adder
Library: 
Arithmetic 
Introduced: 
2.0 Beta 11 
Appearance: 

Behavior
This component adds two values coming in via the west inputs and
outputs the sum on the east output. The component is designed so that it
can be cascaded with other adders to provide add more bits than is
possible with a single adder: The carryin input provides a
onebit value to be added into the sum also (if it is specified), and a
carryout output provides a onebit overflow value that can be fed to
another adder.
If either of the addends contains some floating bits or some error
bits, then the component will perform a partial addition. That is, it
will compute as many loworder bits as possible. But above the floating
or error bit, the result will have floating or error bits.
Pins
 West edge, north end (input, bit width matches Bit Width attribute)
 One of the two values to add.
 West edge, south end (input, bit width matches Bit Width attribute)
 The other of the two values to add.
 North edge, labeled c in (input, bit width 1)
 A carry value to add into the sum. If the value is unknown (i.e.,
floating), then it is assumed to be 0.
 East edge (output, bit width matches Bit Width attribute)
 The lower bitWidth bits of the sum of the two values
coming in the west edge, plus the c_{in}
bit.
 South edge, labeled c out (output, bit width 1)
 The carry bit computed for the sum. If the values added together as
unsigned values do not yield a result that fits into bitWidth
bits, then this bit will be 0; otherwise, it will be 1.
Attributes
 Data Bits
 The bit width of the values to be added and of the result.
Poke Tool Behavior
None.
Text Tool Behavior
None.
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