1 files changed, 69 insertions, 0 deletions
diff --git a/hex2rom.py b/hex2rom.py
new file mode 100644
index 0000000..52610c7
--- /dev/null
+++ b/hex2rom.py
@@ -0,0 +1,69 @@
+#!/usr/bin/env python3
+"""Convert a SDCC/gputils Intel HEX file to a prog_rom.vhd constant.
+
+Usage:
+    python3 hex2rom.py program.hex > PIC/prog_rom.vhd
+    python3 hex2rom.py blink.hex   > PIC/prog_rom.vhd
+"""
+
+import sys
+import argparse
+
+DEPTH = 1024
+INST_BITS = 14
+
+def parse_ihex(path):
+    words = [0] * DEPTH
+    with open(path) as f:
+        for line in f:
+            line = line.strip()
+            if not line.startswith(':'):
+                continue
+            byte_count  = int(line[1:3],   16)
+            address     = int(line[3:7],   16)
+            record_type = int(line[7:9],   16)
+            if record_type != 0:
+                continue
+            data = bytes.fromhex(line[9:9 + byte_count * 2])
+            # PIC16: two bytes per 14-bit word, little-endian, address in bytes
+            for i in range(0, len(data) - 1, 2):
+                word_addr = (address + i) // 2
+                if word_addr < DEPTH:
+                    words[word_addr] = (data[i] | (data[i+1] << 8)) & 0x3FFF
+    return words
+
+def render(words):
+    lines = []
+    lines.append('library ieee;')
+    lines.append('use ieee.std_logic_1164.all;')
+    lines.append('use ieee.numeric_std.all;')
+    lines.append('')
+    lines.append('entity prog_rom is')
+    lines.append('  generic (')
+    lines.append(f'    DEPTH : positive := {DEPTH}')
+    lines.append('  );')
+    lines.append('  port (')
+    lines.append('    addr : in  std_logic_vector(12 downto 0);')
+    lines.append('    data : out std_logic_vector(13 downto 0)')
+    lines.append('  );')
+    lines.append('end entity prog_rom;')
+    lines.append('')
+    lines.append('architecture rtl of prog_rom is')
+    lines.append(f'  type rom_t is array (0 to {DEPTH} - 1) of std_logic_vector(13 downto 0);')
+    lines.append('  constant rom : rom_t := (')
+    for i, w in enumerate(words):
+        bits = format(w, f'014b')
+        sep = ',' if i < DEPTH - 1 else ' '
+        lines.append(f'    {i:4d} => "{bits}"{sep}')
+    lines.append('  );')
+    lines.append('begin')
+    lines.append('  data <= rom(to_integer(unsigned(addr(9 downto 0))));')
+    lines.append('end architecture rtl;')
+    return '\n'.join(lines) + '\n'
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser()
+    parser.add_argument('hexfile')
+    args = parser.parse_args()
+    words = parse_ihex(args.hexfile)
+    print(render(words), end='')