Rewrite update_crc_catalog in zig and move tests to separate file

3 files changed, 282 insertions, 40 deletions

diff --git a/tools/crc/catalog.txt b/tools/crc/catalog.txt
new file mode 100644
index 0000000000..a437141447
--- /dev/null
+++ b/tools/crc/catalog.txt
@@ -0,0 +1,113 @@
+# https://reveng.sourceforge.io/crc-catalogue/all.htm
+width=3  poly=0x3  init=0x0  refin=false  refout=false  xorout=0x7  check=0x4  residue=0x2  name="CRC-3/GSM"
+width=3  poly=0x3  init=0x7  refin=true  refout=true  xorout=0x0  check=0x6  residue=0x0  name="CRC-3/ROHC"
+width=4  poly=0x3  init=0x0  refin=true  refout=true  xorout=0x0  check=0x7  residue=0x0  name="CRC-4/G-704"
+width=4  poly=0x3  init=0xf  refin=false  refout=false  xorout=0xf  check=0xb  residue=0x2  name="CRC-4/INTERLAKEN"
+width=5  poly=0x09  init=0x09  refin=false  refout=false  xorout=0x00  check=0x00  residue=0x00  name="CRC-5/EPC-C1G2"
+width=5  poly=0x15  init=0x00  refin=true  refout=true  xorout=0x00  check=0x07  residue=0x00  name="CRC-5/G-704"
+width=5  poly=0x05  init=0x1f  refin=true  refout=true  xorout=0x1f  check=0x19  residue=0x06  name="CRC-5/USB"
+width=6  poly=0x27  init=0x3f  refin=false  refout=false  xorout=0x00  check=0x0d  residue=0x00  name="CRC-6/CDMA2000-A"
+width=6  poly=0x07  init=0x3f  refin=false  refout=false  xorout=0x00  check=0x3b  residue=0x00  name="CRC-6/CDMA2000-B"
+width=6  poly=0x19  init=0x00  refin=true  refout=true  xorout=0x00  check=0x26  residue=0x00  name="CRC-6/DARC"
+width=6  poly=0x03  init=0x00  refin=true  refout=true  xorout=0x00  check=0x06  residue=0x00  name="CRC-6/G-704"
+width=6  poly=0x2f  init=0x00  refin=false  refout=false  xorout=0x3f  check=0x13  residue=0x3a  name="CRC-6/GSM"
+width=7  poly=0x09  init=0x00  refin=false  refout=false  xorout=0x00  check=0x75  residue=0x00  name="CRC-7/MMC"
+width=7  poly=0x4f  init=0x7f  refin=true  refout=true  xorout=0x00  check=0x53  residue=0x00  name="CRC-7/ROHC"
+width=7  poly=0x45  init=0x00  refin=false  refout=false  xorout=0x00  check=0x61  residue=0x00  name="CRC-7/UMTS"
+width=8  poly=0x2f  init=0xff  refin=false  refout=false  xorout=0xff  check=0xdf  residue=0x42  name="CRC-8/AUTOSAR"
+width=8  poly=0xa7  init=0x00  refin=true  refout=true  xorout=0x00  check=0x26  residue=0x00  name="CRC-8/BLUETOOTH"
+width=8  poly=0x9b  init=0xff  refin=false  refout=false  xorout=0x00  check=0xda  residue=0x00  name="CRC-8/CDMA2000"
+width=8  poly=0x39  init=0x00  refin=true  refout=true  xorout=0x00  check=0x15  residue=0x00  name="CRC-8/DARC"
+width=8  poly=0xd5  init=0x00  refin=false  refout=false  xorout=0x00  check=0xbc  residue=0x00  name="CRC-8/DVB-S2"
+width=8  poly=0x1d  init=0x00  refin=false  refout=false  xorout=0x00  check=0x37  residue=0x00  name="CRC-8/GSM-A"
+width=8  poly=0x49  init=0x00  refin=false  refout=false  xorout=0xff  check=0x94  residue=0x53  name="CRC-8/GSM-B"
+width=8  poly=0x1d  init=0xff  refin=false  refout=false  xorout=0x00  check=0xb4  residue=0x00  name="CRC-8/HITAG"
+width=8  poly=0x07  init=0x00  refin=false  refout=false  xorout=0x55  check=0xa1  residue=0xac  name="CRC-8/I-432-1"
+width=8  poly=0x1d  init=0xfd  refin=false  refout=false  xorout=0x00  check=0x7e  residue=0x00  name="CRC-8/I-CODE"
+width=8  poly=0x9b  init=0x00  refin=false  refout=false  xorout=0x00  check=0xea  residue=0x00  name="CRC-8/LTE"
+width=8  poly=0x31  init=0x00  refin=true  refout=true  xorout=0x00  check=0xa1  residue=0x00  name="CRC-8/MAXIM-DOW"
+width=8  poly=0x1d  init=0xc7  refin=false  refout=false  xorout=0x00  check=0x99  residue=0x00  name="CRC-8/MIFARE-MAD"
+width=8  poly=0x31  init=0xff  refin=false  refout=false  xorout=0x00  check=0xf7  residue=0x00  name="CRC-8/NRSC-5"
+width=8  poly=0x2f  init=0x00  refin=false  refout=false  xorout=0x00  check=0x3e  residue=0x00  name="CRC-8/OPENSAFETY"
+width=8  poly=0x07  init=0xff  refin=true  refout=true  xorout=0x00  check=0xd0  residue=0x00  name="CRC-8/ROHC"
+width=8  poly=0x1d  init=0xff  refin=false  refout=false  xorout=0xff  check=0x4b  residue=0xc4  name="CRC-8/SAE-J1850"
+width=8  poly=0x07  init=0x00  refin=false  refout=false  xorout=0x00  check=0xf4  residue=0x00  name="CRC-8/SMBUS"
+width=8  poly=0x1d  init=0xff  refin=true  refout=true  xorout=0x00  check=0x97  residue=0x00  name="CRC-8/TECH-3250"
+width=8  poly=0x9b  init=0x00  refin=true  refout=true  xorout=0x00  check=0x25  residue=0x00  name="CRC-8/WCDMA"
+width=10  poly=0x233  init=0x000  refin=false  refout=false  xorout=0x000  check=0x199  residue=0x000  name="CRC-10/ATM"
+width=10  poly=0x3d9  init=0x3ff  refin=false  refout=false  xorout=0x000  check=0x233  residue=0x000  name="CRC-10/CDMA2000"
+width=10  poly=0x175  init=0x000  refin=false  refout=false  xorout=0x3ff  check=0x12a  residue=0x0c6  name="CRC-10/GSM"
+width=11  poly=0x385  init=0x01a  refin=false  refout=false  xorout=0x000  check=0x5a3  residue=0x000  name="CRC-11/FLEXRAY"
+width=11  poly=0x307  init=0x000  refin=false  refout=false  xorout=0x000  check=0x061  residue=0x000  name="CRC-11/UMTS"
+width=12  poly=0xf13  init=0xfff  refin=false  refout=false  xorout=0x000  check=0xd4d  residue=0x000  name="CRC-12/CDMA2000"
+width=12  poly=0x80f  init=0x000  refin=false  refout=false  xorout=0x000  check=0xf5b  residue=0x000  name="CRC-12/DECT"
+width=12  poly=0xd31  init=0x000  refin=false  refout=false  xorout=0xfff  check=0xb34  residue=0x178  name="CRC-12/GSM"
+width=12  poly=0x80f  init=0x000  refin=false  refout=true  xorout=0x000  check=0xdaf  residue=0x000  name="CRC-12/UMTS"
+width=13  poly=0x1cf5  init=0x0000  refin=false  refout=false  xorout=0x0000  check=0x04fa  residue=0x0000  name="CRC-13/BBC"
+width=14  poly=0x0805  init=0x0000  refin=true  refout=true  xorout=0x0000  check=0x082d  residue=0x0000  name="CRC-14/DARC"
+width=14  poly=0x202d  init=0x0000  refin=false  refout=false  xorout=0x3fff  check=0x30ae  residue=0x031e  name="CRC-14/GSM"
+width=15  poly=0x4599  init=0x0000  refin=false  refout=false  xorout=0x0000  check=0x059e  residue=0x0000  name="CRC-15/CAN"
+width=15  poly=0x6815  init=0x0000  refin=false  refout=false  xorout=0x0001  check=0x2566  residue=0x6815  name="CRC-15/MPT1327"
+width=16  poly=0x8005  init=0x0000  refin=true  refout=true  xorout=0x0000  check=0xbb3d  residue=0x0000  name="CRC-16/ARC"
+width=16  poly=0xc867  init=0xffff  refin=false  refout=false  xorout=0x0000  check=0x4c06  residue=0x0000  name="CRC-16/CDMA2000"
+width=16  poly=0x8005  init=0xffff  refin=false  refout=false  xorout=0x0000  check=0xaee7  residue=0x0000  name="CRC-16/CMS"
+width=16  poly=0x8005  init=0x800d  refin=false  refout=false  xorout=0x0000  check=0x9ecf  residue=0x0000  name="CRC-16/DDS-110"
+width=16  poly=0x0589  init=0x0000  refin=false  refout=false  xorout=0x0001  check=0x007e  residue=0x0589  name="CRC-16/DECT-R"
+width=16  poly=0x0589  init=0x0000  refin=false  refout=false  xorout=0x0000  check=0x007f  residue=0x0000  name="CRC-16/DECT-X"
+width=16  poly=0x3d65  init=0x0000  refin=true  refout=true  xorout=0xffff  check=0xea82  residue=0x66c5  name="CRC-16/DNP"
+width=16  poly=0x3d65  init=0x0000  refin=false  refout=false  xorout=0xffff  check=0xc2b7  residue=0xa366  name="CRC-16/EN-13757"
+width=16  poly=0x1021  init=0xffff  refin=false  refout=false  xorout=0xffff  check=0xd64e  residue=0x1d0f  name="CRC-16/GENIBUS"
+width=16  poly=0x1021  init=0x0000  refin=false  refout=false  xorout=0xffff  check=0xce3c  residue=0x1d0f  name="CRC-16/GSM"
+width=16  poly=0x1021  init=0xffff  refin=false  refout=false  xorout=0x0000  check=0x29b1  residue=0x0000  name="CRC-16/IBM-3740"
+width=16  poly=0x1021  init=0xffff  refin=true  refout=true  xorout=0xffff  check=0x906e  residue=0xf0b8  name="CRC-16/IBM-SDLC"
+width=16  poly=0x1021  init=0xc6c6  refin=true  refout=true  xorout=0x0000  check=0xbf05  residue=0x0000  name="CRC-16/ISO-IEC-14443-3-A"
+width=16  poly=0x1021  init=0x0000  refin=true  refout=true  xorout=0x0000  check=0x2189  residue=0x0000  name="CRC-16/KERMIT"
+width=16  poly=0x6f63  init=0x0000  refin=false  refout=false  xorout=0x0000  check=0xbdf4  residue=0x0000  name="CRC-16/LJ1200"
+width=16  poly=0x5935  init=0xffff  refin=false  refout=false  xorout=0x0000  check=0x772b  residue=0x0000  name="CRC-16/M17"
+width=16  poly=0x8005  init=0x0000  refin=true  refout=true  xorout=0xffff  check=0x44c2  residue=0xb001  name="CRC-16/MAXIM-DOW"
+width=16  poly=0x1021  init=0xffff  refin=true  refout=true  xorout=0x0000  check=0x6f91  residue=0x0000  name="CRC-16/MCRF4XX"
+width=16  poly=0x8005  init=0xffff  refin=true  refout=true  xorout=0x0000  check=0x4b37  residue=0x0000  name="CRC-16/MODBUS"
+width=16  poly=0x080b  init=0xffff  refin=true  refout=true  xorout=0x0000  check=0xa066  residue=0x0000  name="CRC-16/NRSC-5"
+width=16  poly=0x5935  init=0x0000  refin=false  refout=false  xorout=0x0000  check=0x5d38  residue=0x0000  name="CRC-16/OPENSAFETY-A"
+width=16  poly=0x755b  init=0x0000  refin=false  refout=false  xorout=0x0000  check=0x20fe  residue=0x0000  name="CRC-16/OPENSAFETY-B"
+width=16  poly=0x1dcf  init=0xffff  refin=false  refout=false  xorout=0xffff  check=0xa819  residue=0xe394  name="CRC-16/PROFIBUS"
+width=16  poly=0x1021  init=0xb2aa  refin=true  refout=true  xorout=0x0000  check=0x63d0  residue=0x0000  name="CRC-16/RIELLO"
+width=16  poly=0x1021  init=0x1d0f  refin=false  refout=false  xorout=0x0000  check=0xe5cc  residue=0x0000  name="CRC-16/SPI-FUJITSU"
+width=16  poly=0x8bb7  init=0x0000  refin=false  refout=false  xorout=0x0000  check=0xd0db  residue=0x0000  name="CRC-16/T10-DIF"
+width=16  poly=0xa097  init=0x0000  refin=false  refout=false  xorout=0x0000  check=0x0fb3  residue=0x0000  name="CRC-16/TELEDISK"
+width=16  poly=0x1021  init=0x89ec  refin=true  refout=true  xorout=0x0000  check=0x26b1  residue=0x0000  name="CRC-16/TMS37157"
+width=16  poly=0x8005  init=0x0000  refin=false  refout=false  xorout=0x0000  check=0xfee8  residue=0x0000  name="CRC-16/UMTS"
+width=16  poly=0x8005  init=0xffff  refin=true  refout=true  xorout=0xffff  check=0xb4c8  residue=0xb001  name="CRC-16/USB"
+width=16  poly=0x1021  init=0x0000  refin=false  refout=false  xorout=0x0000  check=0x31c3  residue=0x0000  name="CRC-16/XMODEM"
+width=17  poly=0x1685b  init=0x00000  refin=false  refout=false  xorout=0x00000  check=0x04f03  residue=0x00000  name="CRC-17/CAN-FD"
+width=21  poly=0x102899  init=0x000000  refin=false  refout=false  xorout=0x000000  check=0x0ed841  residue=0x000000  name="CRC-21/CAN-FD"
+width=24  poly=0x00065b  init=0x555555  refin=true  refout=true  xorout=0x000000  check=0xc25a56  residue=0x000000  name="CRC-24/BLE"
+width=24  poly=0x5d6dcb  init=0xfedcba  refin=false  refout=false  xorout=0x000000  check=0x7979bd  residue=0x000000  name="CRC-24/FLEXRAY-A"
+width=24  poly=0x5d6dcb  init=0xabcdef  refin=false  refout=false  xorout=0x000000  check=0x1f23b8  residue=0x000000  name="CRC-24/FLEXRAY-B"
+width=24  poly=0x328b63  init=0xffffff  refin=false  refout=false  xorout=0xffffff  check=0xb4f3e6  residue=0x144e63  name="CRC-24/INTERLAKEN"
+width=24  poly=0x864cfb  init=0x000000  refin=false  refout=false  xorout=0x000000  check=0xcde703  residue=0x000000  name="CRC-24/LTE-A"
+width=24  poly=0x800063  init=0x000000  refin=false  refout=false  xorout=0x000000  check=0x23ef52  residue=0x000000  name="CRC-24/LTE-B"
+width=24  poly=0x864cfb  init=0xb704ce  refin=false  refout=false  xorout=0x000000  check=0x21cf02  residue=0x000000  name="CRC-24/OPENPGP"
+width=24  poly=0x800063  init=0xffffff  refin=false  refout=false  xorout=0xffffff  check=0x200fa5  residue=0x800fe3  name="CRC-24/OS-9"
+width=30  poly=0x2030b9c7  init=0x3fffffff  refin=false  refout=false  xorout=0x3fffffff  check=0x04c34abf  residue=0x34efa55a  name="CRC-30/CDMA"
+width=31  poly=0x04c11db7  init=0x7fffffff  refin=false  refout=false  xorout=0x7fffffff  check=0x0ce9e46c  residue=0x4eaf26f1  name="CRC-31/PHILIPS"
+width=32  poly=0x814141ab  init=0x00000000  refin=false  refout=false  xorout=0x00000000  check=0x3010bf7f  residue=0x00000000  name="CRC-32/AIXM"
+width=32  poly=0xf4acfb13  init=0xffffffff  refin=true  refout=true  xorout=0xffffffff  check=0x1697d06a  residue=0x904cddbf  name="CRC-32/AUTOSAR"
+width=32  poly=0xa833982b  init=0xffffffff  refin=true  refout=true  xorout=0xffffffff  check=0x87315576  residue=0x45270551  name="CRC-32/BASE91-D"
+width=32  poly=0x04c11db7  init=0xffffffff  refin=false  refout=false  xorout=0xffffffff  check=0xfc891918  residue=0xc704dd7b  name="CRC-32/BZIP2"
+width=32  poly=0x8001801b  init=0x00000000  refin=true  refout=true  xorout=0x00000000  check=0x6ec2edc4  residue=0x00000000  name="CRC-32/CD-ROM-EDC"
+width=32  poly=0x04c11db7  init=0x00000000  refin=false  refout=false  xorout=0xffffffff  check=0x765e7680  residue=0xc704dd7b  name="CRC-32/CKSUM"
+width=32  poly=0x1edc6f41  init=0xffffffff  refin=true  refout=true  xorout=0xffffffff  check=0xe3069283  residue=0xb798b438  name="CRC-32/ISCSI"
+width=32  poly=0x04c11db7  init=0xffffffff  refin=true  refout=true  xorout=0xffffffff  check=0xcbf43926  residue=0xdebb20e3  name="CRC-32/ISO-HDLC"
+width=32  poly=0x04c11db7  init=0xffffffff  refin=true  refout=true  xorout=0x00000000  check=0x340bc6d9  residue=0x00000000  name="CRC-32/JAMCRC"
+width=32  poly=0x741b8cd7  init=0xffffffff  refin=true  refout=true  xorout=0x00000000  check=0xd2c22f51  residue=0x00000000  name="CRC-32/MEF"
+width=32  poly=0x04c11db7  init=0xffffffff  refin=false  refout=false  xorout=0x00000000  check=0x0376e6e7  residue=0x00000000  name="CRC-32/MPEG-2"
+width=32  poly=0x000000af  init=0x00000000  refin=false  refout=false  xorout=0x00000000  check=0xbd0be338  residue=0x00000000  name="CRC-32/XFER"
+width=40  poly=0x0004820009  init=0x0000000000  refin=false  refout=false  xorout=0xffffffffff  check=0xd4164fc646  residue=0xc4ff8071ff  name="CRC-40/GSM"
+width=64  poly=0x42f0e1eba9ea3693  init=0x0000000000000000  refin=false  refout=false  xorout=0x0000000000000000  check=0x6c40df5f0b497347  residue=0x0000000000000000  name="CRC-64/ECMA-182"
+width=64  poly=0x000000000000001b  init=0xffffffffffffffff  refin=true  refout=true  xorout=0xffffffffffffffff  check=0xb90956c775a41001  residue=0x5300000000000000  name="CRC-64/GO-ISO"
+width=64  poly=0x259c84cba6426349  init=0xffffffffffffffff  refin=true  refout=true  xorout=0x0000000000000000  check=0x75d4b74f024eceea  residue=0x0000000000000000  name="CRC-64/MS"
+width=64  poly=0xad93d23594c935a9  init=0x0000000000000000  refin=true  refout=true  xorout=0x0000000000000000  check=0xe9c6d914c4b8d9ca  residue=0x0000000000000000  name="CRC-64/REDIS"
+width=64  poly=0x42f0e1eba9ea3693  init=0xffffffffffffffff  refin=false  refout=false  xorout=0xffffffffffffffff  check=0x62ec59e3f1a4f00a  residue=0xfcacbebd5931a992  name="CRC-64/WE"
+width=64  poly=0x42f0e1eba9ea3693  init=0xffffffffffffffff  refin=true  refout=true  xorout=0xffffffffffffffff  check=0x995dc9bbdf1939fa  residue=0x49958c9abd7d353f  name="CRC-64/XZ"
+width=82  poly=0x0308c0111011401440411  init=0x000000000000000000000  refin=true  refout=true  xorout=0x000000000000000000000  check=0x09ea83f625023801fd612  residue=0x000000000000000000000  name="CRC-82/DARC"
diff --git a/tools/update_crc_catalog.sh b/tools/update_crc_catalog.sh
deleted file mode 100755
index 16fbd4487d..0000000000
--- a/tools/update_crc_catalog.sh
+++ /dev/null
@@ -1,40 +0,0 @@
-if [ $# -lt 1 ]; then
-    echo "Usage: $0 /path/git/zig"
-    exit 1
-fi
-
-filepath=$1/lib/std/hash/crc/catalog.zig
-
-cat <<EOS >$filepath
-//! This file is auto-generated by tools/update_crc_catalog.sh.
-
-const std = @import("../../std.zig");
-const testing = std.testing;
-const crc = @import("../crc.zig");
-const Algorithm = crc.Algorithm;
-const Crc = crc.Crc;
-EOS
-
-curl -s https://reveng.sourceforge.io/crc-catalogue/all.htm | grep -o 'width.*name.*"' | while read -r line; do
-    width=$(echo $line | sed 's/width=\([0-9]*\) \(.*\) name="\(.*\)"/\1/')
-    params=$(echo $line | sed 's/width=\([0-9]*\) \(.*\) name="\(.*\)"/\2/' | sed 's/ /, ./g' | sed 's/=/ = /g')
-    name=$(echo $line | sed 's/width=\([0-9]*\) \(.*\) name="\(.*\)"/\3/')
-    snakecase=$(echo $name | sed 's/[-\/]/_/g' | tr '[:upper:]' '[:lower:]')
-    camelcase=$(echo $snakecase | perl -pe 's/(^|_)(\w)/\U$2/g')
-
-    cat <<EOS >>$filepath
-
-const $snakecase: Algorithm(u$width) = .{ .$params };
-
-pub const $camelcase = Crc(u$width, $snakecase);
-
-test "$name" {
-    try testing.expectEqual($snakecase.check, $camelcase.hash("123456789"));
-
-    var c = $camelcase.init();
-    c.update("1234");
-    c.update("56789");
-    try testing.expectEqual($snakecase.check, c.final());
-}
-EOS
-done
diff --git a/tools/update_crc_catalog.zig b/tools/update_crc_catalog.zig
new file mode 100644
index 0000000000..8182e8d810
--- /dev/null
+++ b/tools/update_crc_catalog.zig
@@ -0,0 +1,169 @@
+const std = @import("std");
+const fs = std.fs;
+const mem = std.mem;
+const ascii = std.ascii;
+
+const catalog_txt = @embedFile("crc/catalog.txt");
+
+pub fn main() anyerror!void {
+    var arena_state = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+    defer arena_state.deinit();
+    const arena = arena_state.allocator();
+
+    const args = try std.process.argsAlloc(arena);
+    if (args.len <= 1) {
+        usageAndExit(std.io.getStdErr(), args[0], 1);
+    }
+
+    const zig_src_root = args[1];
+    if (mem.startsWith(u8, zig_src_root, "-")) {
+        usageAndExit(std.io.getStdErr(), args[0], 1);
+    }
+
+    var zig_src_dir = try fs.cwd().openDir(zig_src_root, .{});
+    defer zig_src_dir.close();
+
+    const target_sub_path = try fs.path.join(arena, &.{ "lib", "std", "hash", "crc" });
+    var target_dir = try zig_src_dir.makeOpenPath(target_sub_path, .{});
+    defer target_dir.close();
+
+    var zig_code_file = try target_dir.createFile("catalog.zig", .{});
+    defer zig_code_file.close();
+
+    var cbw = std.io.bufferedWriter(zig_code_file.writer());
+    defer cbw.flush() catch unreachable;
+    const code_writer = cbw.writer();
+
+    try code_writer.writeAll(
+        \\//! This file is auto-generated by tools/update_crc_catalog.zig.
+        \\
+        \\const Crc = @import("../crc.zig").Crc;
+        \\
+        \\test {
+        \\    _ = @import("catalog_test.zig");
+        \\}
+        \\
+    );
+
+    var zig_test_file = try target_dir.createFile("catalog_test.zig", .{});
+    defer zig_test_file.close();
+
+    var tbw = std.io.bufferedWriter(zig_test_file.writer());
+    defer tbw.flush() catch unreachable;
+    const test_writer = tbw.writer();
+
+    try test_writer.writeAll(
+        \\//! This file is auto-generated by tools/update_crc_catalog.zig.
+        \\
+        \\const std = @import("../../std.zig");
+        \\const testing = std.testing;
+        \\const catalog = @import("catalog.zig");
+        \\
+    );
+
+    var stream = std.io.fixedBufferStream(catalog_txt);
+    const reader = stream.reader();
+
+    while (try reader.readUntilDelimiterOrEofAlloc(arena, '\n', std.math.maxInt(usize))) |line| {
+        if (line.len == 0 or line[0] == '#')
+            continue;
+
+        var width: []const u8 = undefined;
+        var poly: []const u8 = undefined;
+        var init: []const u8 = undefined;
+        var refin: []const u8 = undefined;
+        var refout: []const u8 = undefined;
+        var xorout: []const u8 = undefined;
+        var check: []const u8 = undefined;
+        var residue: []const u8 = undefined;
+        var name: []const u8 = undefined;
+
+        var it = mem.split(u8, line, "  ");
+        while (it.next()) |property| {
+            const i = mem.indexOf(u8, property, "=").?;
+            const key = property[0..i];
+            const value = property[i + 1 ..];
+            if (mem.eql(u8, key, "width")) {
+                width = value;
+            } else if (mem.eql(u8, key, "poly")) {
+                poly = value;
+            } else if (mem.eql(u8, key, "init")) {
+                init = value;
+            } else if (mem.eql(u8, key, "refin")) {
+                refin = value;
+            } else if (mem.eql(u8, key, "refout")) {
+                refout = value;
+            } else if (mem.eql(u8, key, "xorout")) {
+                xorout = value;
+            } else if (mem.eql(u8, key, "check")) {
+                check = value;
+            } else if (mem.eql(u8, key, "residue")) {
+                residue = value;
+            } else if (mem.eql(u8, key, "name")) {
+                name = mem.trim(u8, value, "\"");
+            } else {
+                unreachable;
+            }
+        }
+
+        const snakecase = try ascii.allocLowerString(arena, name);
+        defer arena.free(snakecase);
+
+        _ = mem.replace(u8, snakecase, "-", "_", snakecase);
+        _ = mem.replace(u8, snakecase, "/", "_", snakecase);
+
+        var buf = try std.ArrayList(u8).initCapacity(arena, snakecase.len);
+        defer buf.deinit();
+
+        var prev: u8 = 0;
+        for (snakecase) |c, i| {
+            if (c == '_') {
+                // do nothing
+            } else if (i == 0) {
+                buf.appendAssumeCapacity(ascii.toUpper(c));
+            } else if (prev == '_') {
+                buf.appendAssumeCapacity(ascii.toUpper(c));
+            } else {
+                buf.appendAssumeCapacity(c);
+            }
+            prev = c;
+        }
+
+        const camelcase = buf.items;
+
+        try code_writer.writeAll(try std.fmt.allocPrint(arena,
+            \\
+            \\pub const {s} = Crc(u{s}, .{{
+            \\    .polynomial = {s},
+            \\    .initial = {s},
+            \\    .reflect_input = {s},
+            \\    .reflect_output = {s},
+            \\    .xor_output = {s},
+            \\}});
+            \\
+        , .{ camelcase, width, poly, init, refin, refout, xorout }));
+
+        try test_writer.writeAll(try std.fmt.allocPrint(arena,
+            \\
+            \\test "{0s}" {{
+            \\    const {1s} = catalog.{1s};
+            \\
+            \\    try testing.expectEqual(@as(u{2s}, {3s}), {1s}.hash("123456789"));
+            \\
+            \\    var c = {1s}.init();
+            \\    c.update("1234");
+            \\    c.update("56789");
+            \\    try testing.expectEqual(@as(u{2s}, {3s}), c.final());
+            \\}}
+            \\
+        , .{ name, camelcase, width, check }));
+    }
+}
+
+fn usageAndExit(file: fs.File, arg0: []const u8, code: u8) noreturn {
+    file.writer().print(
+        \\Usage: {s} /path/git/zig
+        \\
+    , .{arg0}) catch std.process.exit(1);
+    std.process.exit(code);
+}