The ARI1 macro is responsible for representing all arithmetic operations in the pre-layout phase.
Figure 16-5. ARI1
Table 16-7. ARI1 I/O
Input
Output
A, B, C, D, FCI
Y, S, FCO
The ARI1 cell has a 20 bit INIT string parameter that is used to configure its functionality. The interpretation of the 16 LSB of the INIT string is shown in the following table. F0 is the value of Y when A = 0 and F1 is the value of Y when A = 1.
Table 16-8. Interpretation of 16 LSB of the INIT String for ARI1
ADCB
Y
0000
INIT[0]
F0
0001
INIT[1]
0010
INIT[2]
0011
INIT[3]
0100
INIT[4]
0101
INIT[5]
0110
INIT[6]
0111
INIT[7]
1000
INIT[8]
F1
1001
INIT[9]
1010
INIT[10]
1011
INIT[11]
1100
INIT[12]
1101
INIT[13]
1110
INIT[14]
1111
INIT[15]
Table 16-9. ARI1 Truth Table for S
Y
FCI
S
0
0
0
0
1
1
1
0
1
1
1
0
ARI1 LOGIC
The 4 MSB of the INIT string controls the output of the carry bits. The carry is
generated using carry propagation and generation bits, which are evaluated according to
the following tables.
CFG1, CFG2, CFG3, and CFG4 are post-layout LUTs that implement any 1-input, 2-input, 3-input, and 4-input combinational logic functions respectively. Each of the CFG1/2/3/4 macros has an INIT string parameter that determines the logic functions of the macro. The output Y is dependent on the INIT string parameter and the values of the inputs.
Post-layout macro implements any 2-input combinational logic function.
Output Y is dependent on the INIT string parameter and the value of A and B. The INIT
string parameter is 4 bits wide.Figure 16-8. CFG2
Post-layout macro used to implement any 3-input combinational logic
function. Output Y is dependent on the INIT string parameter and the value of A, B, and C.
The INIT string parameter is 8 bits wide.
Post-layout macro used to implement any 4-input combinational logic
function. Output Y is dependent on the INIT string parameter and the value of A, B, C, and
D. The INIT string parameter is 16 bits wide.
