Description

CENG232
Logic Design
Lab-4 Part-1

1 Function Operations (Individual Work)
This part of the lab will be performed and submitted individually.
In this part, you are expected to implement basic memories as 2 Verilog modules. These modules will be used to store the functions, evaluate and store the result of evaluations.
1.1 Problem Definition
Each function will be in the form: a4x4 + a3x3 + a2x2 + a1x1 + a0x0. The module FUNCROM will contain 16 registers. Each register holds a 5-bit binary number which represents the coefficients of the function starting from a4 through a0. The values of a4 through a0 can either get +1 or -1: These values are represented in a register as 0 and 1, respectively. Examples of 3 registers and the functions they represent are given in the below table:
Register Value Function
00000 x4 + x3 + x2 + x + 1
01010 x4−x3 + x2−x + 1
11110 −x4−x3−x2−x + 1
Given the index value as input, FUNCROM module basically returns the register value stored at that index as output. It works as a combinational circuit. The values of FUNCROM will be as the following table:
Index Register Value
0000 00000
0001 00010
0010 00100
0011 00111
0100 01010
0101 01011
0110 01101
0111 01110
1000 10001
1001 10010
1010 10100
1011 10111
1100 11001
1101 11010
1110 11110
1111 11111
The module FUNCRAM will contain 16 registers. Each register contains 9 bits. Initially, the values of all RAM registers will be 9’b000000000. FUNCRAM module basically has two functionalities: 1) Reading data in given index, 2) Writing data into memory. These are determined by the modes given below:
• mode(1 bit):
0 → read mode
1 → write mode
Write Mode
In write mode, your task is to evaluate the modulo 7/derivative of the function with the given argument and store the result in the FUNCRAM. The input will be a 7-bit number. The first 4 bits of the input are used as an index to select the functions from the FUNCROM. The fifth bit is used to determine the type of the operation. If the value of fifth bit is 0, the function with the given the argument will be evaluated which is followed by mod 7 operation and the final result is calculated. If the value of fifth bit is 1, the derivative of the function will be evaluated with the given argument. The last 2 bits of the input correspond to the argument of the function where binary 00, 01, 10 and 11 will represent +2,+1,-1 and -2 in decimal, respectively. The output will be a 9-bit number where the most significant bit denotes the sign (0 if positive and 1 if negative). The examples are given in the below table:
Input ROM
Index Operation
Type Arg. Function At Given
ROM Index Calculation Output
0000000 0000 modulo 7 2 P(x) = x4 + x3 + x2 + x1 + 1 P(2) = 24 + 23 + 22 + 2 + 1 = 31
P(2) modulo 7 = 31 mod 7 = 3 000000011
0000101 0000 derivative 1 P(x) = x4 + x3 + x2 + x1 + 1 P0(x) = 4×3 + 3×2 + 2x + 1
P0(1) = 4 + 3 + 2 + 1 = 10 000001010
1111100 1111 derivative 2 P(x) = −x4−x3−x2−x1− 1 P0(x) = −4×3− 3×2− 2x− 1
P0(2) = −32 − 12 − 4 − 1 = −49 100110001
The output will be stored in a register of FUNCRAM. The index of that register is the first four bits of the input. Please note that multiple write operation on the same index will overwrite the previous value in that index. The operation will be done with the rising edge of the clock pulse.
Read Mode
In read mode, the value in given index location of FUNCRAM will be returned as output. There will be no write operation to the FUNCRAM in this mode. This operation is combinational, and is not triggered by a clock pulse.
The FUNCROM and FUNCRAM modules will be used by an upper module called FUNCMEMORY. FUNCMEMORY is an interface for FUNCROM and FUNCRAM modules. The module definition of FUNCMEMORY is given below:
module FUNCMEMORY(input mode, input [6:0] memInput, input CLK, output wire [8:0] result)
where mode represents FUNCRAM read/write mode, memInput represents the 7-bit input used in FUNCRAM and FUNCROM modules and result represents the 9-bit output stored in FUNCRAM.
The module definitions of FUNCROM and FUNCRAM are as follows:
module FUNCROM (input [3:0] romAddress, output reg[4:0] romData)
where romAddress represents the index of ROM register and romData represents the register value given the romAddress value.
module FUNCRAM (input mode,input [3:0] ramAddress, input [4:0] dataIn,input op, input [1:0] arg, input CLK, output reg [8:0] dataOut)
where mode represents read/write mode, ramAddress represents the index of the FUNCRAM register to store the output, dataIn represents the coefficient values of the function, op represents the type of operation (i.e. modulo 7/derivative of the function), arg represents the 2-bit argument of the function and dataOut represents the 9-bit output stored in FUNCRAM.
You will implement only FUNCROM and FUNCRAM modules. FUNCMEMORY module will be provided for you and will not be implemented.
Deliverables
• Implement both modules in a single Verilog file: lab4 1.v. Do NOT submit your test-benches. You can share your test-benches on the newsgroup.
• This part is supposed to be done individually, not with your partner. Any kind of cheating is not allowed.