rocket-chip/vsim/vlsi_mem_gen

#! /usr/bin/env python

# See LICENSE for license details.

import sys
import math

use_latches = 0

def parse_line(line):
  name = ''
  width = 0
  depth = 0
  ports = ''
  mask_gran = 1
  tokens = line.split()
  i = 0
  for i in range(0,len(tokens),2):
    s = tokens[i]
    if s == 'name':
      name = tokens[i+1]
    elif s == 'width':
      width = int(tokens[i+1])
    elif s == 'depth':
      depth = int(tokens[i+1])
    elif s == 'ports':
      ports = tokens[i+1].split(',')
    elif s == 'mask_gran':
      # currently used only for fpga, but here for .conf format compatability
      mask_gran = int(tokens[i+1])
    else:
      sys.exit('%s: unknown argument %s' % (sys.argv[0], a))
  return (name, width, depth, ports)

def gen_mem(name, width, depth, ports):
  addr_width = max(math.ceil(math.log(depth)/math.log(2)),1)
  port_spec = ['input CLK', 'input RST', 'input init']
  readports = []
  writeports = []
  latchports = []
  rwports = []
  decl = []
  combinational = []
  sequential = []
  maskedports = {}
  for pid in range(len(ports)):
    ptype = ports[pid]
    if ptype[0:1] == 'm':
      ptype = ptype[1:]
      maskedports[pid] = pid

    if ptype == 'read':
      port_spec.append('input [%d:0] R%dA' % (addr_width-1, pid))
      port_spec.append('input R%dE' % pid)
      port_spec.append('output [%d:0] R%dO' % (width-1, pid))
      readports.append(pid)
    elif ptype == 'write':
      port_spec.append('input [%d:0] W%dA' % (addr_width-1, pid))
      port_spec.append('input W%dE' % pid)
      port_spec.append('input [%d:0] W%dI' % (width-1, pid))
      if pid in maskedports:
        port_spec.append('input [%d:0] W%dM' % (width-1, pid))
      if not use_latches or pid in maskedports:
        writeports.append(pid)
      else:
        latchports.append(pid)
    elif ptype == 'rw':
      port_spec.append('input [%d:0] RW%dA' % (addr_width-1, pid))
      port_spec.append('input RW%dE' % pid)
      port_spec.append('input RW%dW' % pid)
      if pid in maskedports:
        port_spec.append('input [%d:0] RW%dM' % (width-1, pid))
      port_spec.append('input [%d:0] RW%dI' % (width-1, pid))
      port_spec.append('output [%d:0] RW%dO' % (width-1, pid))
      rwports.append(pid)
    else:
      sys.exit('%s: unknown port type %s' % (sys.argv[0], ptype))

  nr = len(readports)
  nw = len(writeports)
  nrw = len(rwports)
  masked = len(maskedports)>0
  tup = (depth, width, nr, nw, nrw, masked)

  decl.append('reg [%d:0] ram [%d:0];' % (width-1, depth-1))
  decl.append('`ifndef SYNTHESIS')
  decl.append('  integer initvar;')
  decl.append('  initial begin')
  decl.append('    #0.002;')
  decl.append('    for (initvar = 0; initvar < %d; initvar = initvar+1)' % depth)
  decl.append('      ram[initvar] = {%d {$random}};' % ((width-1)/32+1))
  decl.append('  end')
  decl.append('`endif')

  for pid in readports:
    decl.append('reg [%d:0] reg_R%dA;' % (addr_width-1, pid))
    sequential.append('if (R%dE) reg_R%dA <= R%dA;' % (pid, pid, pid))
    combinational.append('assign R%dO = ram[reg_R%dA];' % (pid, pid))

  for pid in rwports:
    decl.append('reg [%d:0] reg_RW%dA;' % (addr_width-1, pid))
    sequential.append('if (RW%dE && !RW%dW) reg_RW%dA <= RW%dA;' % (pid, pid, pid, pid))
    combinational.append('assign RW%dO = ram[reg_RW%dA];' % (pid, pid))

  for pid in latchports:
    decl.append('reg [%d:0] latch_W%dA;' % (addr_width-1, pid))
    decl.append('reg [%d:0] latch_W%dI;' % (width-1, pid))
    decl.append('reg latch_W%dE;' % (pid))
    combinational.append('always @(*) begin')
    combinational.append('  if (!CLK && W%dE) latch_W%dA <= W%dA;' % (pid, pid, pid))
    combinational.append('  if (!CLK && W%dE) latch_W%dI <= W%dI;' % (pid, pid, pid))
    combinational.append('  if (!CLK) latch_W%dE <= W%dE;' % (pid, pid))
    combinational.append('end')
    combinational.append('always @(*)')
    combinational.append('  if (CLK && latch_W%dE)' % (pid))
    combinational.append('    ram[latch_W%dA] <= latch_W%dI;' % (pid, pid))

  decl.append("integer i;")
  sequential.append("for (i = 0; i < %d; i=i+1) begin" % width)
  for pid in writeports:
    mask = (' && W%dM[i]' % pid) if pid in maskedports else ''
    sequential.append("  if (W%dE%s) ram[W%dA][i] <= W%dI[i];" % (pid, mask, pid, pid))
  for pid in rwports:
    mask = (' && RW%dM[i]' % pid) if pid in maskedports else ''
    sequential.append("  if (RW%dE && RW%dW%s) ram[RW%dA][i] <= RW%dI[i];" % (pid, pid, mask, pid, pid))
  sequential.append("end")
  body = "\
  %s\n\
  always @(posedge CLK) begin\n\
    %s\n\
  end\n\
  %s\n" % ('\n  '.join(decl), '\n    '.join(sequential), '\n  '.join(combinational))

  s = "module %s(\n\
  %s\n\
);\n\
\n\
%s\
\n\
endmodule\n" % (name, ',\n  '.join(port_spec), body)
  return s

def main():
  if len(sys.argv) < 2:
    sys.exit('Please give a .conf file as input')
  for line in open(sys.argv[1]):
    print(gen_mem(*parse_line(line)))

if __name__ == '__main__':
  main()