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some minor version updates
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@gsquire
gsquire committed Mar 27, 2024
1 parent bb8ea92 commit 06e3d31
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Showing 2 changed files with 73 additions and 52 deletions.
21 changes: 21 additions & 0 deletions encode
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Original file line number Diff line number Diff line change
@@ -0,0 +1,21 @@
MIT License

Copyright (c) 2020 Garrett Squire

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
104 changes: 52 additions & 52 deletions snappy.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -55,7 +55,7 @@ fn uvarint(buf: []const u8) Varint {
var x: u64 = 0;
var s: u6 = 0; // We can shift a maximum of 2^6 (64) times.

for (buf) |b, i| {
for (buf, 0..) |b, i| {
if (b < 0x80) {
if (i > 9 or i == 9 and b > 1) {
return Varint{
Expand Down Expand Up @@ -84,11 +84,11 @@ fn putUvarint(buf: []u8, x: u64) usize {
var mutX = x;

while (mutX >= 0x80) {
buf[i] = @truncate(u8, mutX) | 0x80;
buf[i] = @as(u8, @truncate(mutX)) | 0x80;
mutX >>= 7;
i += 1;
}
buf[i] = @truncate(u8, mutX);
buf[i] = @as(u8, @truncate(mutX));

return i + 1;
}
Expand Down Expand Up @@ -172,8 +172,8 @@ fn runDecode(dst: []u8, src: []const u8) u8 {
return 1;
}

mem.copy(u8, dst[d..], src[s .. s + @intCast(usize, length)]);
const l = @intCast(usize, length);
mem.copy(u8, dst[d..], src[s .. s + @as(usize, @intCast(length))]);
const l = @as(usize, @intCast(length));
d += l;
s += l;
continue;
Expand Down Expand Up @@ -216,20 +216,20 @@ fn runDecode(dst: []u8, src: []const u8) u8 {
}

if (offset >= length) {
const upper_bound = d - @intCast(usize, offset) + @intCast(usize, length);
mem.copy(u8, dst[d .. d + @intCast(usize, length)], dst[d - @intCast(usize, offset) .. upper_bound]);
d += @intCast(usize, length);
const upper_bound = d - @as(usize, @intCast(offset)) + @as(usize, @intCast(length));
mem.copy(u8, dst[d .. d + @as(usize, @intCast(length))], dst[d - @as(usize, @intCast(offset)) .. upper_bound]);
d += @as(usize, @intCast(length));
continue;
}

var a = dst[d .. d + @intCast(usize, length)];
var b = dst[d - @intCast(usize, offset) ..];
var a = dst[d .. d + @as(usize, @intCast(length))];
var b = dst[d - @as(usize, @intCast(offset)) ..];
var aLen = a.len;
b = b[0..aLen];
for (a) |_, i| {
for (a, 0..) |_, i| {
a[i] = b[i];
}
d += @intCast(usize, length);
d += @as(usize, @intCast(length));
}

if (d != dst.len) {
Expand Down Expand Up @@ -260,43 +260,43 @@ pub fn decode(allocator: Allocator, src: []const u8) ![]u8 {
// TODO: Split up encode and decode into separate files once I better understand modules.
fn emitLiteral(dst: []u8, lit: []const u8) usize {
var i: usize = 0;
const n = @intCast(usize, lit.len - 1);
const n = @as(usize, @intCast(lit.len - 1));
switch (n) {
0...59 => {
dst[0] = @intCast(u8, n) << 2 | tagLiteral;
dst[0] = @as(u8, @intCast(n)) << 2 | tagLiteral;
i = 1;
},
60...255 => {
dst[0] = 60 << 2 | tagLiteral;
dst[1] = @intCast(u8, n);
dst[1] = @as(u8, @intCast(n));
i = 2;
},
else => {
dst[0] = 61 << 2 | tagLiteral;
dst[1] = @intCast(u8, n);
dst[2] = @intCast(u8, n >> 8);
dst[1] = @as(u8, @intCast(n));
dst[2] = @as(u8, @intCast(n >> 8));
i = 3;
},
}
mem.copy(u8, dst[i..], lit);

return i + std.math.min(dst.len, lit.len);
return i + @min(dst.len, lit.len);
}

fn load32(b: []u8, i: isize) u32 {
const j = @intCast(usize, i);
const j = @as(usize, @intCast(i));
const v = b[j .. j + 4];
return @intCast(u32, v[0]) | @intCast(u32, v[1]) << 8 | @intCast(u32, v[2]) << 16 | @intCast(u32, v[3]) << 24;
return @as(u32, @intCast(v[0])) | @as(u32, @intCast(v[1])) << 8 | @as(u32, @intCast(v[2])) << 16 | @as(u32, @intCast(v[3])) << 24;
}

fn load64(b: []u8, i: isize) u64 {
const j = @intCast(usize, i);
const j = @as(usize, @intCast(i));
const v = b[j .. j + 8];
return @intCast(u64, v[0]) | @intCast(u64, v[1]) << 8 | @intCast(u64, v[2]) << 16 | @intCast(u64, v[3]) << 24 | @intCast(u64, v[4]) << 32 | @intCast(u64, v[5]) << 40 | @intCast(u64, v[6]) << 48 | @intCast(u64, v[7]) << 56;
return @as(u64, @intCast(v[0])) | @as(u64, @intCast(v[1])) << 8 | @as(u64, @intCast(v[2])) << 16 | @as(u64, @intCast(v[3])) << 24 | @as(u64, @intCast(v[4])) << 32 | @as(u64, @intCast(v[5])) << 40 | @as(u64, @intCast(v[6])) << 48 | @as(u64, @intCast(v[7])) << 56;
}

fn snappyHash(u: u32, shift: u32) u32 {
const s = @intCast(u5, shift);
const s = @as(u5, @intCast(shift));
return (u *% 0x1e35a7bd) >> s;
}

Expand All @@ -306,30 +306,30 @@ fn emitCopy(dst: []u8, offset: isize, length: isize) usize {

while (l >= 68) {
dst[i + 0] = 63 << 2 | tagCopy2;
dst[i + 1] = @truncate(u8, @intCast(usize, offset));
dst[i + 2] = @truncate(u8, @intCast(usize, offset >> 8));
dst[i + 1] = @as(u8, @truncate(@as(usize, @intCast(offset))));
dst[i + 2] = @as(u8, @truncate(@as(usize, @intCast(offset >> 8))));
i += 3;
l -= 64;
}

if (l > 64) {
dst[i + 0] = 59 << 2 | tagCopy2;
dst[i + 1] = @truncate(u8, @intCast(usize, offset));
dst[i + 2] = @truncate(u8, @intCast(usize, offset >> 8));
dst[i + 1] = @as(u8, @truncate(@as(usize, @intCast(offset))));
dst[i + 2] = @as(u8, @truncate(@as(usize, @intCast(offset >> 8))));
//mem.copy(u8, dst, &mem.toBytes(offset));
i += 3;
l -= 60;
}

if (l >= 12 or offset >= 2048) {
dst[i + 0] = (@intCast(u8, l) -% 1) << 2 | tagCopy2;
dst[i + 1] = @truncate(u8, @intCast(usize, offset));
dst[i + 2] = @truncate(u8, @intCast(usize, offset >> 8));
dst[i + 0] = (@as(u8, @intCast(l)) -% 1) << 2 | tagCopy2;
dst[i + 1] = @as(u8, @truncate(@as(usize, @intCast(offset))));
dst[i + 2] = @as(u8, @truncate(@as(usize, @intCast(offset >> 8))));
return i + 3;
}

dst[i + 0] = @truncate(u8, @intCast(usize, offset >> 8)) << 5 | (@intCast(u8, l) -% 4) << 2 | tagCopy1;
dst[i + 1] = @truncate(u8, @intCast(usize, offset));
dst[i + 0] = @as(u8, @truncate(@as(usize, @intCast(offset >> 8)))) << 5 | (@as(u8, @intCast(l)) -% 4) << 2 | tagCopy1;
dst[i + 1] = @as(u8, @truncate(@as(usize, @intCast(offset))));
return i + 2;
}

Expand All @@ -349,7 +349,7 @@ fn encodeBlock(dst: []u8, src: []u8) usize {
var sLimit = src.len - inputMargin;
var nextEmit: usize = 0;
var s: usize = 1;
var nextHash = snappyHash(load32(src, @intCast(isize, s)), shift);
var nextHash = snappyHash(load32(src, @as(isize, @intCast(s))), shift);

outer: while (true) {
var skip: isize = 32;
Expand All @@ -359,15 +359,15 @@ fn encodeBlock(dst: []u8, src: []u8) usize {
inner: while (true) {
s = nextS;
var bytesBetweenHashLookups = skip >> 5;
nextS = s + @intCast(usize, bytesBetweenHashLookups);
nextS = s + @as(usize, @intCast(bytesBetweenHashLookups));
skip += bytesBetweenHashLookups;
if (nextS > sLimit) {
break :outer;
}
candidate = @intCast(isize, table[nextHash & tableMask]);
table[nextHash & tableMask] = @intCast(u16, s);
nextHash = snappyHash(load32(src, @intCast(isize, nextS)), shift);
if (load32(src, @intCast(isize, s)) == load32(src, candidate)) {
candidate = @as(isize, @intCast(table[nextHash & tableMask]));
table[nextHash & tableMask] = @as(u16, @intCast(s));
nextHash = snappyHash(load32(src, @as(isize, @intCast(nextS))), shift);
if (load32(src, @as(isize, @intCast(s))) == load32(src, candidate)) {
break :inner;
}
}
Expand All @@ -377,26 +377,26 @@ fn encodeBlock(dst: []u8, src: []u8) usize {
while (true) {
var base = s;
s += 4;
var i = @intCast(usize, candidate + 4);
var i = @as(usize, @intCast(candidate + 4));
while (s < src.len and src[i] == src[s]) {
i += 1;
s += 1;
}

d += emitCopy(dst[d..], @intCast(isize, base - @intCast(usize, candidate)), @intCast(isize, s - base));
d += emitCopy(dst[d..], @as(isize, @intCast(base - @as(usize, @intCast(candidate)))), @as(isize, @intCast(s - base)));
nextEmit = s;
if (s >= sLimit) {
break :outer;
}

var x = load64(src, @intCast(isize, s - 1));
var prevHash = snappyHash(@truncate(u32, x >> 0), shift);
table[prevHash & tableMask] = @intCast(u16, s - 1);
var currHash = snappyHash(@truncate(u32, x >> 8), shift);
candidate = @intCast(isize, table[currHash & tableMask]);
table[currHash & tableMask] = @intCast(u16, s);
if (@truncate(u32, x >> 8) != load32(src, candidate)) {
nextHash = snappyHash(@truncate(u32, x >> 16), shift);
var x = load64(src, @as(isize, @intCast(s - 1)));
var prevHash = snappyHash(@as(u32, @truncate(x >> 0)), shift);
table[prevHash & tableMask] = @as(u16, @intCast(s - 1));
var currHash = snappyHash(@as(u32, @truncate(x >> 8)), shift);
candidate = @as(isize, @intCast(table[currHash & tableMask]));
table[currHash & tableMask] = @as(u16, @intCast(s));
if (@as(u32, @truncate(x >> 8)) != load32(src, candidate)) {
nextHash = snappyHash(@as(u32, @truncate(x >> 16)), shift);
s += 1;
break;
}
Expand All @@ -418,10 +418,10 @@ pub fn encode(allocator: Allocator, src: []u8) ![]u8 {
return SnappyError.TooLarge;
}

var dst = try allocator.alloc(u8, @intCast(usize, encodedLen));
var dst = try allocator.alloc(u8, @as(usize, @intCast(encodedLen)));
errdefer allocator.free(dst);

var d = putUvarint(dst, @intCast(u64, mutSrc.len));
var d = putUvarint(dst, @as(u64, @intCast(mutSrc.len)));

while (mutSrc.len > 0) {
var p = try allocator.alloc(u8, mutSrc.len);
Expand All @@ -445,7 +445,7 @@ pub fn encode(allocator: Allocator, src: []u8) ![]u8 {

/// Return the maximum length of a snappy block, given the uncompressed length.
pub fn maxEncodedLen(srcLen: usize) isize {
var n = @intCast(u64, srcLen);
var n = @as(u64, @intCast(srcLen));
if (n > 0xffffffff) {
return -1;
}
Expand All @@ -455,7 +455,7 @@ pub fn maxEncodedLen(srcLen: usize) isize {
return -1;
}

return @intCast(isize, n);
return @as(isize, @intCast(n));
}

test "snappy crc" {
Expand Down

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