authorgravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2025-07-27 14:10:55-07:00
committergravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2025-07-31 22:10:11-07:00
log73c98ca0e6aa52b942b92135ecf0305362030733
tree6f379ddf66c752fce123ec5ef3a300372940af28
parenta4f05a4588100c5e7f311dd5319e97e394f109a4

simplify std.hash.Adler32

4 files changed, 120 insertions(+), 138 deletions(-)

lib/std/hash.zig+2-3
......@@ -1,5 +1,4 @@
1const adler = @import("hash/adler.zig");
2pub const Adler32 = adler.Adler32;
1pub const Adler32 = @import("hash/Adler32.zig");
32
43const auto_hash = @import("hash/auto_hash.zig");
54pub const autoHash = auto_hash.autoHash;
......@@ -116,7 +115,7 @@ test int {
116115}
117116
118117test {
119 _ = adler;
118 _ = Adler32;
120119 _ = auto_hash;
121120 _ = crc;
122121 _ = fnv;
lib/std/hash/Adler32.zig created+117
......@@ -0,0 +1,117 @@
1//! https://tools.ietf.org/html/rfc1950#section-9
2//! https://github.com/madler/zlib/blob/master/adler32.c
3
4const Adler32 = @This();
5const std = @import("std");
6const testing = std.testing;
7
8adler: u32 = 1,
9
10pub fn permute(state: u32, input: []const u8) u32 {
11 const base = 65521;
12 const nmax = 5552;
13
14 var s1 = state & 0xffff;
15 var s2 = (state >> 16) & 0xffff;
16
17 if (input.len == 1) {
18 s1 +%= input[0];
19 if (s1 >= base) {
20 s1 -= base;
21 }
22 s2 +%= s1;
23 if (s2 >= base) {
24 s2 -= base;
25 }
26 } else if (input.len < 16) {
27 for (input) |b| {
28 s1 +%= b;
29 s2 +%= s1;
30 }
31 if (s1 >= base) {
32 s1 -= base;
33 }
34
35 s2 %= base;
36 } else {
37 const n = nmax / 16; // note: 16 | nmax
38
39 var i: usize = 0;
40
41 while (i + nmax <= input.len) {
42 var rounds: usize = 0;
43 while (rounds < n) : (rounds += 1) {
44 comptime var j: usize = 0;
45 inline while (j < 16) : (j += 1) {
46 s1 +%= input[i + j];
47 s2 +%= s1;
48 }
49 i += 16;
50 }
51
52 s1 %= base;
53 s2 %= base;
54 }
55
56 if (i < input.len) {
57 while (i + 16 <= input.len) : (i += 16) {
58 comptime var j: usize = 0;
59 inline while (j < 16) : (j += 1) {
60 s1 +%= input[i + j];
61 s2 +%= s1;
62 }
63 }
64 while (i < input.len) : (i += 1) {
65 s1 +%= input[i];
66 s2 +%= s1;
67 }
68
69 s1 %= base;
70 s2 %= base;
71 }
72 }
73
74 return s1 | (s2 << 16);
75}
76
77pub fn update(a: *Adler32, input: []const u8) void {
78 a.adler = permute(a.adler, input);
79}
80
81pub fn hash(input: []const u8) u32 {
82 return permute(1, input);
83}
84
85test "sanity" {
86 try testing.expectEqual(@as(u32, 0x620062), hash("a"));
87 try testing.expectEqual(@as(u32, 0xbc002ed), hash("example"));
88}
89
90test "long" {
91 const long1 = [_]u8{1} ** 1024;
92 try testing.expectEqual(@as(u32, 0x06780401), hash(long1[0..]));
93
94 const long2 = [_]u8{1} ** 1025;
95 try testing.expectEqual(@as(u32, 0x0a7a0402), hash(long2[0..]));
96}
97
98test "very long" {
99 const long = [_]u8{1} ** 5553;
100 try testing.expectEqual(@as(u32, 0x707f15b2), hash(long[0..]));
101}
102
103test "very long with variation" {
104 const long = comptime blk: {
105 @setEvalBranchQuota(7000);
106 var result: [6000]u8 = undefined;
107
108 var i: usize = 0;
109 while (i < result.len) : (i += 1) {
110 result[i] = @as(u8, @truncate(i));
111 }
112
113 break :blk result;
114 };
115
116 try testing.expectEqual(@as(u32, 0x5af38d6e), hash(long[0..]));
117}
lib/std/hash/adler.zig deleted-134
......@@ -1,134 +0,0 @@
1// Adler32 checksum.
2//
3// https://tools.ietf.org/html/rfc1950#section-9
4// https://github.com/madler/zlib/blob/master/adler32.c
5
6const std = @import("std");
7const testing = std.testing;
8
9pub const Adler32 = struct {
10 const base = 65521;
11 const nmax = 5552;
12
13 adler: u32,
14
15 pub fn init() Adler32 {
16 return Adler32{ .adler = 1 };
17 }
18
19 // This fast variant is taken from zlib. It reduces the required modulos and unrolls longer
20 // buffer inputs and should be much quicker.
21 pub fn update(self: *Adler32, input: []const u8) void {
22 var s1 = self.adler & 0xffff;
23 var s2 = (self.adler >> 16) & 0xffff;
24
25 if (input.len == 1) {
26 s1 +%= input[0];
27 if (s1 >= base) {
28 s1 -= base;
29 }
30 s2 +%= s1;
31 if (s2 >= base) {
32 s2 -= base;
33 }
34 } else if (input.len < 16) {
35 for (input) |b| {
36 s1 +%= b;
37 s2 +%= s1;
38 }
39 if (s1 >= base) {
40 s1 -= base;
41 }
42
43 s2 %= base;
44 } else {
45 const n = nmax / 16; // note: 16 | nmax
46
47 var i: usize = 0;
48
49 while (i + nmax <= input.len) {
50 var rounds: usize = 0;
51 while (rounds < n) : (rounds += 1) {
52 comptime var j: usize = 0;
53 inline while (j < 16) : (j += 1) {
54 s1 +%= input[i + j];
55 s2 +%= s1;
56 }
57 i += 16;
58 }
59
60 s1 %= base;
61 s2 %= base;
62 }
63
64 if (i < input.len) {
65 while (i + 16 <= input.len) : (i += 16) {
66 comptime var j: usize = 0;
67 inline while (j < 16) : (j += 1) {
68 s1 +%= input[i + j];
69 s2 +%= s1;
70 }
71 }
72 while (i < input.len) : (i += 1) {
73 s1 +%= input[i];
74 s2 +%= s1;
75 }
76
77 s1 %= base;
78 s2 %= base;
79 }
80 }
81
82 self.adler = s1 | (s2 << 16);
83 }
84
85 pub fn final(self: *Adler32) u32 {
86 return self.adler;
87 }
88
89 pub fn hash(input: []const u8) u32 {
90 var c = Adler32.init();
91 c.update(input);
92 return c.final();
93 }
94};
95
96test "adler32 sanity" {
97 try testing.expectEqual(@as(u32, 0x620062), Adler32.hash("a"));
98 try testing.expectEqual(@as(u32, 0xbc002ed), Adler32.hash("example"));
99}
100
101test "adler32 long" {
102 const long1 = [_]u8{1} ** 1024;
103 try testing.expectEqual(@as(u32, 0x06780401), Adler32.hash(long1[0..]));
104
105 const long2 = [_]u8{1} ** 1025;
106 try testing.expectEqual(@as(u32, 0x0a7a0402), Adler32.hash(long2[0..]));
107}
108
109test "adler32 very long" {
110 const long = [_]u8{1} ** 5553;
111 try testing.expectEqual(@as(u32, 0x707f15b2), Adler32.hash(long[0..]));
112}
113
114test "adler32 very long with variation" {
115 const long = comptime blk: {
116 @setEvalBranchQuota(7000);
117 var result: [6000]u8 = undefined;
118
119 var i: usize = 0;
120 while (i < result.len) : (i += 1) {
121 result[i] = @as(u8, @truncate(i));
122 }
123
124 break :blk result;
125 };
126
127 try testing.expectEqual(@as(u32, 0x5af38d6e), std.hash.Adler32.hash(long[0..]));
128}
129
130const verify = @import("verify.zig");
131
132test "adler32 iterative" {
133 try verify.iterativeApi(Adler32);
134}
lib/std/hash/verify.zig+1-1
......@@ -45,7 +45,7 @@ pub fn smhasher(comptime hash_fn: anytype) u32 {
4545
4646pub fn iterativeApi(comptime Hash: anytype) !void {
4747 // Sum(1..32) = 528
48 var buf: [528]u8 = [_]u8{0} ** 528;
48 var buf: [528]u8 = @splat(0);
4949 var len: usize = 0;
5050 const seed = 0;
5151