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rocket-chip/scripts/vlsi_rom_gen

139 lines
3.6 KiB
Python
Executable File

#! /usr/bin/env python
# See LICENSE.SiFive for license details.
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals
import doctest
import sys
import warnings
from collections import namedtuple
verilog_template = """
module {name}(
input clock,
input oe,
input me,
input [{address_bits_minus_1}:0] address,
output [{output_width_minus_1}:0] q
);
reg [{output_width_minus_1}:0] out;
reg [{output_width_minus_1}:0] rom [0:{depth_minus_1}];
// 1024 is the maximum length of $readmemh filename supported by Cadence Incisive
reg [1024 * 8 - 1:0] path;
integer i;
initial begin
`ifdef RANDOMIZE
`ifdef RANDOMIZE_MEM_INIT
for (i = 0; i < {depth}; i = i + 1) begin
rom[i] = {{{num_random_blocks}{{$random}}}};
end
`endif
`endif
if (!$value$plusargs("maskromhex=%s", path)) begin
path = "{rom_hex_file}";
end
$readmemh(path, rom);
end
always @(posedge clock) begin
if (me) begin
out <= rom[address];
end
end
assign q = oe ? out : {output_width}'bZ;
endmodule
"""
def gen_rom(name, width, depth, rom_hex_file):
variables = {
'name': name,
'address_bits_minus_1': (depth - 1).bit_length() - 1,
'depth': depth,
'depth_minus_1': depth - 1,
'output_width': width,
'output_width_minus_1': width - 1,
# $random in verilog returns 32 bits; compute how many times to repeat
# $random in order to fill the width
'num_random_blocks': (width - 1) // 32 + 1,
'rom_hex_file': rom_hex_file,
}
return verilog_template.format(**variables)
def iterate_by_n(it, n):
"""Iterate over items in it, yielding n-tuples of successive items.
>>> list(iterate_by_n([1, 2, 3, 4, 5, 6], n=2))
[(1, 2), (3, 4), (5, 6)]
>>> list(iterate_by_n([1, 2, 3, 4, 5, 6], n=3))
[(1, 2, 3), (4, 5, 6)]
>>> list(iterate_by_n([1, 2, 3, 4, 5, 6], n=4))
Traceback (most recent call last):
...
ValueError: Iterable length not evenly divisible by 4
"""
it = iter(it)
while True:
batch = ()
for i in range(n):
try:
batch += (next(it),)
except StopIteration:
if batch: # If this is not the first iteration
raise ValueError(
'Iterable length not evenly divisible by {}'.format(n)
)
else:
raise
yield batch
def try_cast_int(x):
try:
return int(x)
except ValueError:
return x
ROMParameters = namedtuple('ROMParameters', ['name', 'depth', 'width'])
default_rom_parameters = ROMParameters(name='', depth=0, width=0)
def parse_line(line):
kwargs = {key: try_cast_int(val)
for key, val in iterate_by_n(line.split(), 2)}
rom_parameters = default_rom_parameters._replace(**kwargs)
return rom_parameters._asdict()
def main():
if '--run-tests' in sys.argv:
(failures, total) = doctest.testmod(verbose=True)
sys.exit(1 if failures else 0)
if len(sys.argv) < 2:
sys.exit('Please give a .conf file as input')
print('// This file created by ' + __file__)
with open(sys.argv[1]) as fp:
lines = fp.readlines()
if len(lines) > 1:
warnings.warn('vlsi_rom_gen detected multiple ROMs. ROM contents will be duplicated.')
for line in lines:
verilog = gen_rom(rom_hex_file=sys.argv[2],
**parse_line(line))
print(verilog)
if __name__ == '__main__':
main()