Read binary file data in Verilog into 2D Array - verilog

Question

I have an array that I want to load up from a binary file:
parameter c_ROWS = 8;
parameter c_COLS = 16;
reg [15:0] r_Image_Raw[0:c_ROWS-1][0:c_COLS-1];
My input file is binary data, 256 bytes long (same total space as r_Image_Raw). I tried using $fread to accomplish this, but it only works through the 4th column of the last row:
n_File_ID = $fopen(s_File_Name, "r");
n_Temp = $fread(r_Image_Raw, n_File_ID);
I also tried using $fscanf for this, but I get an error about packed types when opening the synthesis tool:
while (!$feof(n_File_ID))
n_Temp = $fscanf(n_File_ID, "%h", r_Image_Raw);
I feel like this should be easy to do. Do I have create a 2D for loop and loop through the r_Image_Raw variable, reading in 16 bits at a time? I feel like it should not be that complicated.

Answer 1

I realized my mistake. It should be:
n_File_ID = $fopen(s_File_Name, "rb");
n_Temp = $fread(r_Image_Raw, n_File_ID);
I was using "r" and not "rb" to specify that it was a binary file. Interestingly enough, "r" does work for the majority of the data, but it is unable read in the last ~13 locations from the file.

Answer 2

Try this.
f_bin = $fopen(s_File_Name,"rb");
for (r = 0; r < c_ROWS; r = r+1) begin
for (c = 0; c < c_COLS; c = c+1) begin
f = $fread(r16,f_bin);
r_Image_Raw[r][c] = r16;
end
end
See that $fread(r16,f_bin) first param is reg, second - file!

Answer 3

Below an example for reading from a binary file with systemverilog.
As shown in IEEE SV Standard documentation, the "nchar_code" will return the number of bytes/chars read. In case EOF have been already reached on last read this number will be zero.
Please, notice that "nchar_code" can be zero but EOF has not been reached, this happens if you have spaces or returns at the end of the data file.
You can control the number of bytes to be read with the $fread function. This is done with the type definition of the "data_write_temp" or "mem" of the below examples. If the "data_write_temp" variable is 16bits long then it will read 16bits each time the $fread is called. Besides, $fread will return "nchar_code=2" because 16bits are 2bytes. In case, "data_write_temp" is 32bits as in the example, the $fread will read nchar_code=4bytes(32bits). You can also define an array and the $fread function will try to fill that array.
Lets define a multidimensional array mem.
logic [31:0] mem [0:2][0:4][5:8];
In the example word contents, wzyx,
-w shows the start of the word
-z corresponds to words of the [0:2] dimension (3 blocks).
-y corresponds to words of the [0:4] dimension (5 rows).
-x corresponds to words of the [5:8] dimension (4 columns).
The file will be structure as below (notice #z shows the z dimension blocks):
#0 w005 w006 w007 w008
w015 w016 w017 w018
w025 w026 w027 w028
w035 w036 w037 w038
w045 w046 w047 w048
#1 w105 w106 w107 w108
w115 w116 w117 w118
w125 w126 w127 w128
w135 w136 w137 w138
w145 w146 w147 w148
#2 w205 w206 w207 w208
w215 w216 w217 w218
w225 w226 w227 w228
w235 w236 w237 w238
w245 w246 w247 w248
In the previous structure, the numbers shows the index of each dimension.
e.g. w048 means, the word w (32bits) value on index z =0, index y= 4 and index x= 8.
Now, you have many ways to read this.
You can read all in a single shot using the type "mem" declared above, or you can do a while loop until EOF reading pieces of 32bits using a "data_write_temp" variable of 32bits. The loop is interesting if you want to do something some checks for every word piece and you are not interested having a memory value.
In case multidimensional array / single shot read is chosen, then you can either use $fread or use an specific function $readmemh defined in SV standard.
$readmemh("mem.data", mem, 1, (3*5*4));
is equivalent to
$readmemh("mem.data", mem);
The $readmemh spare you the need to open/close the file.
If you use $fread for one shot read
logic [31:0] mem [0:2][0:4][5:8];
register_init_id = $fopen("mem.data","rb");
nchar_code = $fread(mem, register_init_id);
if (nchar_code!=(3*5*4)*4)) begin
`uvm_error("do_read_file", $sformatf("Was not possible to read the whole expected bytes"));
end
$fclose(register_init_id);
In case you wanted to do a loop using 32b word read. Then see the following example.
The example uses the data which is read from the file to write to AHB Bus using an AHB Verification Component.
logic [31:0] data_write_temp;
...
//DO REGISTER FILE
register_init_id = $fopen("../../software/binary.bin","rb");
if (register_init_id==0) begin `uvm_error("do_read_file", $sformatf("Was not possible to open the register_init_id file")); end
count_32b_words=0;
while(!$feof(register_init_id)) begin
nchar_code = $fread(data_write_temp, register_init_id);
if ((nchar_code!=4)||(nchar_code==0)) begin
if (nchar_code!=0) begin
`uvm_error("do_read_file", $sformatf("Was not possible to read from file a whole 4bytes word:%0d",nchar_code));
end
end else begin
tmp_ahb_address = (pnio_pkg::conf_ahb_register_init_file_part1 + 4*count_32b_words);
data_write_temp = (data_write_temp << 8*( (tmp_ahb_address)%(DATAWIDTH/(8))));//bit shift if necessary not aligned to 4 bytes
`uvm_create_on(m_ahb_xfer,p_sequencer.ahb0_seqr);
assert(m_ahb_xfer.randomize(* solvefaildebug *) with {
write == 1;//perform a write
HADDR == tmp_ahb_address;
HSIZE == SIZE_32_BIT;
HBURST == HBURST_SINGLE;
HXDATA.size() == 1; //only one data for single bust
HXDATA[0] == data_write_temp;
}) else $fatal (0, "Randomization failed"); //end assert
`uvm_send(m_ahb_xfer);
count_32b_words++;
end //end if there is a word read
end //end while
$fclose(register_init_id);