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make takeBits deal with integers only

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This commit is contained in:
Andrew Kelley 2025-07-28 20:31:00 -07:00
parent c00fb86db6
commit 63f496c4f9
1 changed files with 11 additions and 25 deletions
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36
lib/std/compress/flate/Decompress.zig
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@ -216,7 +216,7 @@ fn readInner(d: *Decompress, w: *Writer, limit: std.Io.Limit) (Error || Reader.S
},
.block_header => {
d.final_block = (try d.takeBits(u1)) != 0;
const block_type = try d.takeBits(BlockType);
const block_type: BlockType = @enumFromInt(try d.takeBits(u2));
switch (block_type) {
.stored => {
d.alignBitsToByte(); // skip padding until byte boundary
@ -372,41 +372,31 @@ fn writeMatch(w: *Writer, length: u16, distance: u16) !void {
for (dest, src) |*d, s| d.* = s;
}
fn takeBits(d: *Decompress, comptime T: type) !T {
const U = @Type(.{ .int = .{ .signedness = .unsigned, .bits = @bitSizeOf(T) } });
fn takeBits(d: *Decompress, comptime U: type) !U {
const remaining_bits = d.remaining_bits;
const next_bits = d.next_bits;
if (remaining_bits >= @bitSizeOf(T)) {
if (remaining_bits >= @bitSizeOf(U)) {
const u: U = @truncate(next_bits);
d.next_bits = next_bits >> @bitSizeOf(T);
d.remaining_bits = remaining_bits - @bitSizeOf(T);
return switch (@typeInfo(T)) {
.int => u,
.@"enum" => @enumFromInt(u),
else => @bitCast(u),
};
d.next_bits = next_bits >> @bitSizeOf(U);
d.remaining_bits = remaining_bits - @bitSizeOf(U);
return u;
}
const in = d.input;
const next_int = in.takeInt(usize, .little) catch |err| switch (err) {
error.ReadFailed => return error.ReadFailed,
error.EndOfStream => return takeBitsEnding(d, T),
error.EndOfStream => return takeBitsEnding(d, U),
};
const needed_bits = @bitSizeOf(T) - remaining_bits;
const needed_bits = @bitSizeOf(U) - remaining_bits;
const u: U = @intCast(((next_int & ((@as(usize, 1) << needed_bits) - 1)) << remaining_bits) | next_bits);
d.next_bits = next_int >> needed_bits;
d.remaining_bits = @intCast(@bitSizeOf(usize) - @as(usize, needed_bits));
return switch (@typeInfo(T)) {
.int => u,
.@"enum" => @enumFromInt(u),
else => @bitCast(u),
};
return u;
}
fn takeBitsEnding(d: *Decompress, comptime T: type) !T {
fn takeBitsEnding(d: *Decompress, comptime U: type) !U {
const remaining_bits = d.remaining_bits;
const next_bits = d.next_bits;
const in = d.input;
const U = @Type(.{ .int = .{ .signedness = .unsigned, .bits = @bitSizeOf(T) } });
var u: U = 0;
var remaining_needed_bits = @bitSizeOf(U) - remaining_bits;
while (@bitSizeOf(U) >= 8 and remaining_needed_bits >= 8) {
@ -424,11 +414,7 @@ fn takeBitsEnding(d: *Decompress, comptime T: type) !T {
d.remaining_bits = @intCast(8 - remaining_needed_bits);
}
u = @intCast((@as(usize, u) << remaining_bits) | next_bits);
return switch (@typeInfo(T)) {
.int => u,
.@"enum" => @enumFromInt(u),
else => @bitCast(u),
};
return u;
}
fn peekBits(d: *Decompress, comptime U: type) !U {