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src/crc32.erl
-module(crc32).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/crc32.gleam").
-export([finalize/1, update/2, new/0, checksum/1, verify/2]).
-export_type([crc32/0]).
-if(?OTP_RELEASE >= 27).
-define(MODULEDOC(Str), -moduledoc(Str)).
-define(DOC(Str), -doc(Str)).
-else.
-define(MODULEDOC(Str), -compile([])).
-define(DOC(Str), -compile([])).
-endif.
?MODULEDOC(
" Calculate CRC-32/ISO-HDLC checksums in pure Gleam.\n"
"\n"
" This module is the supported public API for the `crc32` package. It provides\n"
" both one-shot checksum calculation and immutable incremental state for data\n"
" processed in chunks.\n"
"\n"
" The implemented algorithm is CRC-32/ISO-HDLC, the conventional reflected\n"
" CRC-32 variant commonly used by ZIP, gzip, PNG, and Ethernet. The standard\n"
" check value for the ASCII bytes `\"123456789\"` is `0xCBF43926`.\n"
"\n"
" The public API intentionally works with `BitArray` values and returns the\n"
" finalized checksum as a Gleam `Int`. Hexadecimal formatting is left to\n"
" callers that need textual output.\n"
"\n"
" ```gleam\n"
" import crc32\n"
"\n"
" pub fn main() {\n"
" let checksum = crc32.checksum(<<\"123456789\":utf8>>)\n"
" assert checksum == 0xCBF43926\n"
" }\n"
" ```\n"
"\n"
" ```gleam\n"
" import crc32\n"
"\n"
" pub fn main() {\n"
" let checksum =\n"
" crc32.new()\n"
" |> crc32.update(<<\"hello \":utf8>>)\n"
" |> crc32.update(<<\"world\":utf8>>)\n"
" |> crc32.finalize()\n"
"\n"
" assert checksum == crc32.checksum(<<\"hello world\":utf8>>)\n"
" }\n"
" ```\n"
"\n"
" CRC-32 is useful for detecting accidental corruption. It is not a\n"
" cryptographic hash and must not be used for authentication or tamper\n"
" resistance.\n"
).
-opaque crc32() :: {crc32, integer()}.
-file("src/crc32.gleam", 115).
-spec table_lookup(integer()) -> integer().
table_lookup(Index) ->
case gleam@list:drop(
[16#00000000,
16#77073096,
16#EE0E612C,
16#990951BA,
16#076DC419,
16#706AF48F,
16#E963A535,
16#9E6495A3,
16#0EDB8832,
16#79DCB8A4,
16#E0D5E91E,
16#97D2D988,
16#09B64C2B,
16#7EB17CBD,
16#E7B82D07,
16#90BF1D91,
16#1DB71064,
16#6AB020F2,
16#F3B97148,
16#84BE41DE,
16#1ADAD47D,
16#6DDDE4EB,
16#F4D4B551,
16#83D385C7,
16#136C9856,
16#646BA8C0,
16#FD62F97A,
16#8A65C9EC,
16#14015C4F,
16#63066CD9,
16#FA0F3D63,
16#8D080DF5,
16#3B6E20C8,
16#4C69105E,
16#D56041E4,
16#A2677172,
16#3C03E4D1,
16#4B04D447,
16#D20D85FD,
16#A50AB56B,
16#35B5A8FA,
16#42B2986C,
16#DBBBC9D6,
16#ACBCF940,
16#32D86CE3,
16#45DF5C75,
16#DCD60DCF,
16#ABD13D59,
16#26D930AC,
16#51DE003A,
16#C8D75180,
16#BFD06116,
16#21B4F4B5,
16#56B3C423,
16#CFBA9599,
16#B8BDA50F,
16#2802B89E,
16#5F058808,
16#C60CD9B2,
16#B10BE924,
16#2F6F7C87,
16#58684C11,
16#C1611DAB,
16#B6662D3D,
16#76DC4190,
16#01DB7106,
16#98D220BC,
16#EFD5102A,
16#71B18589,
16#06B6B51F,
16#9FBFE4A5,
16#E8B8D433,
16#7807C9A2,
16#0F00F934,
16#9609A88E,
16#E10E9818,
16#7F6A0DBB,
16#086D3D2D,
16#91646C97,
16#E6635C01,
16#6B6B51F4,
16#1C6C6162,
16#856530D8,
16#F262004E,
16#6C0695ED,
16#1B01A57B,
16#8208F4C1,
16#F50FC457,
16#65B0D9C6,
16#12B7E950,
16#8BBEB8EA,
16#FCB9887C,
16#62DD1DDF,
16#15DA2D49,
16#8CD37CF3,
16#FBD44C65,
16#4DB26158,
16#3AB551CE,
16#A3BC0074,
16#D4BB30E2,
16#4ADFA541,
16#3DD895D7,
16#A4D1C46D,
16#D3D6F4FB,
16#4369E96A,
16#346ED9FC,
16#AD678846,
16#DA60B8D0,
16#44042D73,
16#33031DE5,
16#AA0A4C5F,
16#DD0D7CC9,
16#5005713C,
16#270241AA,
16#BE0B1010,
16#C90C2086,
16#5768B525,
16#206F85B3,
16#B966D409,
16#CE61E49F,
16#5EDEF90E,
16#29D9C998,
16#B0D09822,
16#C7D7A8B4,
16#59B33D17,
16#2EB40D81,
16#B7BD5C3B,
16#C0BA6CAD,
16#EDB88320,
16#9ABFB3B6,
16#03B6E20C,
16#74B1D29A,
16#EAD54739,
16#9DD277AF,
16#04DB2615,
16#73DC1683,
16#E3630B12,
16#94643B84,
16#0D6D6A3E,
16#7A6A5AA8,
16#E40ECF0B,
16#9309FF9D,
16#0A00AE27,
16#7D079EB1,
16#F00F9344,
16#8708A3D2,
16#1E01F268,
16#6906C2FE,
16#F762575D,
16#806567CB,
16#196C3671,
16#6E6B06E7,
16#FED41B76,
16#89D32BE0,
16#10DA7A5A,
16#67DD4ACC,
16#F9B9DF6F,
16#8EBEEFF9,
16#17B7BE43,
16#60B08ED5,
16#D6D6A3E8,
16#A1D1937E,
16#38D8C2C4,
16#4FDFF252,
16#D1BB67F1,
16#A6BC5767,
16#3FB506DD,
16#48B2364B,
16#D80D2BDA,
16#AF0A1B4C,
16#36034AF6,
16#41047A60,
16#DF60EFC3,
16#A867DF55,
16#316E8EEF,
16#4669BE79,
16#CB61B38C,
16#BC66831A,
16#256FD2A0,
16#5268E236,
16#CC0C7795,
16#BB0B4703,
16#220216B9,
16#5505262F,
16#C5BA3BBE,
16#B2BD0B28,
16#2BB45A92,
16#5CB36A04,
16#C2D7FFA7,
16#B5D0CF31,
16#2CD99E8B,
16#5BDEAE1D,
16#9B64C2B0,
16#EC63F226,
16#756AA39C,
16#026D930A,
16#9C0906A9,
16#EB0E363F,
16#72076785,
16#05005713,
16#95BF4A82,
16#E2B87A14,
16#7BB12BAE,
16#0CB61B38,
16#92D28E9B,
16#E5D5BE0D,
16#7CDCEFB7,
16#0BDBDF21,
16#86D3D2D4,
16#F1D4E242,
16#68DDB3F8,
16#1FDA836E,
16#81BE16CD,
16#F6B9265B,
16#6FB077E1,
16#18B74777,
16#88085AE6,
16#FF0F6A70,
16#66063BCA,
16#11010B5C,
16#8F659EFF,
16#F862AE69,
16#616BFFD3,
16#166CCF45,
16#A00AE278,
16#D70DD2EE,
16#4E048354,
16#3903B3C2,
16#A7672661,
16#D06016F7,
16#4969474D,
16#3E6E77DB,
16#AED16A4A,
16#D9D65ADC,
16#40DF0B66,
16#37D83BF0,
16#A9BCAE53,
16#DEBB9EC5,
16#47B2CF7F,
16#30B5FFE9,
16#BDBDF21C,
16#CABAC28A,
16#53B39330,
16#24B4A3A6,
16#BAD03605,
16#CDD70693,
16#54DE5729,
16#23D967BF,
16#B3667A2E,
16#C4614AB8,
16#5D681B02,
16#2A6F2B94,
16#B40BBE37,
16#C30C8EA1,
16#5A05DF1B,
16#2D02EF8D],
Index
) of
[Head | _] ->
Head;
[] ->
0
end.
-file("src/crc32.gleam", 122).
-spec update_bytes(integer(), bitstring()) -> integer().
update_bytes(Crc, Data) ->
case Data of
<<>> ->
Crc;
<<Byte, Rest/bitstring>> ->
Crc@1 = erlang:'bxor'(Crc, Byte),
Index = erlang:'band'(Crc@1, 16#FF),
Crc@2 = erlang:'bsr'(Crc@1, 8),
Crc@3 = erlang:'bxor'(Crc@2, table_lookup(Index)),
update_bytes(Crc@3, Rest);
_ ->
Crc
end.
-file("src/crc32.gleam", 204).
?DOC(
" Finalize an incremental calculation and return its CRC-32 checksum.\n"
"\n"
" The returned `Int` is the finalized CRC-32/ISO-HDLC value after the\n"
" algorithm's final XOR step.\n"
"\n"
" ## Examples\n"
"\n"
" ```gleam\n"
" let checksum =\n"
" crc32.new()\n"
" |> crc32.update(data)\n"
" |> crc32.finalize()\n"
" ```\n"
).
-spec finalize(crc32()) -> integer().
finalize(Crc) ->
erlang:'bxor'(erlang:element(2, Crc), 16#FFFFFFFF).
-file("src/crc32.gleam", 186).
?DOC(
" Feed another chunk of bytes into an incremental CRC-32 calculation.\n"
"\n"
" This function is pipeline-friendly and returns a new state value. Updating\n"
" with multiple chunks produces the same finalized checksum as processing the\n"
" concatenated bytes in a single call to [`checksum`](#checksum).\n"
"\n"
" ## Examples\n"
"\n"
" ```gleam\n"
" crc32.new()\n"
" |> crc32.update(<<\"hello \":utf8>>)\n"
" |> crc32.update(<<\"world\":utf8>>)\n"
" |> crc32.finalize()\n"
" // => same as crc32.checksum(<<\"hello world\":utf8>>)\n"
" ```\n"
).
-spec update(crc32(), bitstring()) -> crc32().
update(Crc, Data) ->
{crc32, update_bytes(erlang:element(2, Crc), Data)}.
-file("src/crc32.gleam", 166).
?DOC(
" Start a new incremental CRC-32/ISO-HDLC calculation.\n"
"\n"
" The returned state uses the standard initial value for CRC-32/ISO-HDLC.\n"
" Pass the state to [`update`](#update) for each chunk of input and then\n"
" finish with [`finalize`](#finalize).\n"
"\n"
" ## Examples\n"
"\n"
" ```gleam\n"
" let crc = crc32.new()\n"
" ```\n"
).
-spec new() -> crc32().
new() ->
{crc32, 16#FFFFFFFF}.
-file("src/crc32.gleam", 148).
?DOC(
" Calculate the CRC-32/ISO-HDLC checksum of the complete input.\n"
"\n"
" This is the convenience entry point for callers that already have all bytes\n"
" available in one `BitArray`. It is equivalent to calling [`new`](#new),\n"
" [`update`](#update), and then [`finalize`](#finalize).\n"
"\n"
" ## Examples\n"
"\n"
" ```gleam\n"
" let value = crc32.checksum(<<\"hello\":utf8>>)\n"
" ```\n"
).
-spec checksum(bitstring()) -> integer().
checksum(Data) ->
_pipe = new(),
_pipe@1 = update(_pipe, Data),
finalize(_pipe@1).
-file("src/crc32.gleam", 223).
?DOC(
" Finalize an incremental calculation and compare it with an expected checksum.\n"
"\n"
" This is a convenience helper for verification workflows. The `expected`\n"
" value should be the finalized CRC-32/ISO-HDLC checksum, typically written as\n"
" a hexadecimal integer literal in source code.\n"
"\n"
" ## Examples\n"
"\n"
" ```gleam\n"
" let valid =\n"
" crc32.new()\n"
" |> crc32.update(data)\n"
" |> crc32.verify(expected)\n"
" ```\n"
).
-spec verify(crc32(), integer()) -> boolean().
verify(Crc, Expected) ->
finalize(Crc) =:= Expected.