diff options
Diffstat (limited to 'icecompr')
| -rw-r--r-- | icecompr/icecompr.cc | 24 | ||||
| -rw-r--r-- | icecompr/icecompr.py | 129 |
2 files changed, 135 insertions, 18 deletions
diff --git a/icecompr/icecompr.cc b/icecompr/icecompr.cc index 322de9a..04e2a09 100644 --- a/icecompr/icecompr.cc +++ b/icecompr/icecompr.cc @@ -1,21 +1,9 @@ -/* - * IceCompr -- A simple compressor for iCE40 bit-streams - * - * Copyright (C) 2017 Clifford Wolf <clifford@clifford.at> - * - * Permission to use, copy, modify, and/or distribute this software for any - * purpose with or without fee is hereby granted, provided that the above - * copyright notice and this permission notice appear in all copies. - * - * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES - * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF - * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR - * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES - * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN - * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF - * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. - * - */ +// This is free and unencumbered software released into the public domain. +// +// Anyone is free to copy, modify, publish, use, compile, sell, or +// distribute this software, either in source code form or as a compiled +// binary, for any purpose, commercial or non-commercial, and by any +// means. #include <stdio.h> #include <stdlib.h> diff --git a/icecompr/icecompr.py b/icecompr/icecompr.py new file mode 100644 index 0000000..886c1a9 --- /dev/null +++ b/icecompr/icecompr.py @@ -0,0 +1,129 @@ +#!/usr/bin/env python3 +# +# This is free and unencumbered software released into the public domain. +# +# Anyone is free to copy, modify, publish, use, compile, sell, or +# distribute this software, either in source code form or as a compiled +# binary, for any purpose, commercial or non-commercial, and by any +# means. + + +def make_int_bits(value, nbits): + bits = list() + for i in range(nbits-1, -1, -1): + bits.append((value & (1 << i)) != 0) + return bits + +def ice_compress(inbits): + outbits = list() + outbits += make_int_bits(0x49434543, 32) + outbits += make_int_bits(0x4f4d5052, 32) + + deltas = list() + numzeros = 0 + + for bit in inbits: + if bit: + deltas.append(numzeros) + numzeros = 0 + else: + numzeros += 1 + + i = 0 + while i < len(deltas): + raw_len = 0 + compr_len = 0 + best_compr_raw_diff = -1 + best_compr_raw_idx = -1 + best_compr_raw_len = -1 + + for j in range(len(deltas) - i): + delta = deltas[i+j] + raw_len += delta + 1 + + if delta < 4: + compr_len += 3 + elif delta < 32: + compr_len += 7 + elif delta < 256: + compr_len += 11 + else: + compr_len += 26 + + if compr_len - raw_len < max(best_compr_raw_diff - 4, 0) or raw_len > 64: + break + + if compr_len - raw_len > best_compr_raw_diff: + best_compr_raw_diff = compr_len - raw_len + best_compr_raw_idx = j + best_compr_raw_len = raw_len + + if best_compr_raw_diff > 9: + outbits.append(False) + outbits.append(False) + outbits.append(False) + outbits.append(True) + outbits += make_int_bits(best_compr_raw_len-1, 6) + + for j in range(0, best_compr_raw_idx+1): + delta = deltas[i+j] + for k in range(delta): + outbits.append(False) + if j < best_compr_raw_idx: + outbits.append(True) + + i += best_compr_raw_idx + 1 + continue + + delta = deltas[i] + i += 1 + + if delta < 4: + outbits.append(True) + outbits += make_int_bits(delta, 2) + elif delta < 32: + outbits.append(False) + outbits.append(True) + outbits += make_int_bits(delta, 5) + elif delta < 256: + outbits.append(False) + outbits.append(False) + outbits.append(True) + outbits += make_int_bits(delta, 8) + else: + outbits.append(False) + outbits.append(False) + outbits.append(False) + outbits.append(False) + outbits.append(True) + outbits += make_int_bits(delta, 23) + + outbits.append(False) + outbits.append(False) + outbits.append(False) + outbits.append(False) + outbits.append(False) + outbits += make_int_bits(numzeros, 23) + + return outbits + + +# ------------------------------------------------------ +# Usage example: +# python3 icecompr.py < example_8k.bin > example_8k.compr + +import sys + +inbits = list() +for byte in sys.stdin.buffer.read(): + for i in range(7, -1, -1): + inbits.append((byte & (1 << i)) != 0) + +outbits = ice_compress(inbits) + +for i in range(0, len(outbits), 8): + byte = 0 + for k in range(i, min(i+8, len(outbits))): + if outbits[k]: byte |= 1 << (7-(k-i)) + sys.stdout.buffer.write(bytes([byte])) + |