rocket-chip/fsim/fpga_mem_gen

#!/usr/bin/env python
import sys
import math

# This is based off of reference-chip/vlsi/src/vlsi_mem_gen

use_latches = 1


module_template = '''module %s(
  %s
);
%s
%s
always @(posedge CLK) begin
  %s
end
%s

endmodule

'''


mask_assert_template = '''
`ifndef SYNTHESIS
integer i;
integer j;
always @(posedge CLK) begin%s
end
`endif
'''


assert_template = '''
  for (i=0; i<%d; i=i+%d) begin
    for (j=1; j<%d; j=j+1) begin
      if (%sM[i] != %sM[i+j]) begin
        $fwrite(32'h80000002, "ASSERTION FAILED: write mask granularity\\n");
        $finish;
      end
    end
  end'''


def parse_line(line):
  name = ''
  width = 0
  depth = 0
  ports = ''
  mask_gran = 1
  tokens = line.split()
  i = 0
  for i in xrange(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':
      mask_gran = int(tokens[i+1])
    else:
      sys.exit('%s: unknown argument %s' % (sys.argv[0], a))
  return (name, width, depth, ports, mask_gran)



def gen_range(mask_index, mask_gran, max_width):
  return '%d:%d' % (min(mask_gran*(mask_index+1),max_width)-1,
                    min(mask_gran*(mask_index),max_width))



def gen_mem(name, width, depth, ports, mask_gran):
  addr_width = max(math.ceil(math.log(depth)/math.log(2)),1)
  mask_width = int(math.ceil(float(width) / mask_gran))
  port_spec = ['input CLK', 'input RST', 'input init']
  readports = []
  writeports = []
  latchports = []
  rwports = []
  decl = []
  combinational = []
  sequential = []
  maskedports = {}
  mask_asserts = ''
  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 += ['input [%d:0] R%dA' % (addr_width-1, pid)]
      port_spec += ['input R%dE' % pid]
      port_spec += ['output [%d:0] R%dO' % (width-1, pid)]
      readports += [pid]
    elif ptype == 'write':
      port_spec += ['input [%d:0] W%dA' % (addr_width-1, pid)]
      port_spec += ['input W%dE' % pid]
      port_spec += ['input [%d:0] W%dI' % (width-1, pid)]
      if pid in maskedports:
        port_spec += ['input [%d:0] W%dM' % (width-1, pid)]
      if not use_latches or pid in maskedports:
        writeports += [pid]
      else:
        latchports += [pid]
    elif ptype == 'rw':
      port_spec += ['input [%d:0] RW%dA' % (addr_width-1, pid)]
      port_spec += ['input RW%dE' % pid]
      port_spec += ['input RW%dW' % pid]
      if pid in maskedports:
        port_spec += ['input [%d:0] RW%dM' % (width-1, pid)]
      port_spec += ['input [%d:0] RW%dI' % (width-1, pid)]
      port_spec += ['output [%d:0] RW%dO' % (width-1, pid)]
      rwports += [pid]
    else:
      sys.exit('%s: unknown port type %s' % (sys.argv[0], ptype))

  decl += ['reg [%d:0] ram [%d:0];' % (width-1, depth-1)]

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

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

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

  for pid in writeports:
    if pid not in maskedports:
      sequential += ['if (W%dE) ram[W%dA] <= W%dI;' % (pid, pid, pid)]
    else:
      for mask_index in range(mask_width):
        rs = gen_range(mask_index, mask_gran, width)
        sequential += ['if (W%dE && W%dM[%d]) ram[W%dA][%s] <= W%dI[%s];' %
                       (pid, pid, mask_index*mask_gran, pid, rs, pid, rs)]
      mask_asserts += assert_template % (mask_width, mask_gran, mask_gran, 'W'+str(pid), 'W'+str(pid))
  for pid in rwports:
    if pid not in maskedports:
      sequential += ['if (RW%dE && RW%dW) ram[RW%dA] <= RW%dI;' % (pid, pid, pid, pid)]
    else:
      for mask_index in range(mask_width):
        rs = gen_range(mask_index, mask_gran, width)
        sequential += ['if (RW%dE && RW%dW && RW%dM[%d]) ram[RW%dA][%s] <= RW%dI[%s];' %
                       (pid, pid, pid, mask_index*mask_gran, pid, rs, pid, rs)]
      mask_asserts += assert_template % (mask_width, mask_gran, mask_gran, 'RW'+str(pid), 'RW'+str(pid))
  check_masks = '' if len(maskedports) == 0 else mask_assert_template % mask_asserts
  return module_template % (name,
                            ',\n  '.join(port_spec),
                            check_masks,
                            '\n  '.join(decl),
                            '\n  '.join(sequential),
                            '\n  '.join(combinational))



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()