Zig 0.17.0-dev (Split by item)

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readVarInt

Reads an integer from memory with size equal to bytes.len. ReturnType specifies the return type, which must be large enough to store the result.

mem.readVarInt

pub fn readVarInt(comptime ReturnType: type, bytes: []const u8, endian: Endian) ReturnType

File

lib/std/mem.zig:1781

Code

pub fn readVarInt(comptime ReturnType: type, bytes: []const u8, endian: Endian) ReturnType {
    assert(@typeInfo(ReturnType).int.bits >= bytes.len * 8);
    const bits = @typeInfo(ReturnType).int.bits;
    const signedness = @typeInfo(ReturnType).int.signedness;
    const WorkType = @Int(signedness, @max(16, bits));
    var result: WorkType = 0;
    switch (endian) {
        .big => {
            for (bytes) |b| {
                result = (result << 8) | b;
            }
        },
        .little => {
            const ShiftType = math.Log2Int(WorkType);
            for (bytes, 0..) |b, index| {
                result = result | (@as(WorkType, b) << @as(ShiftType, @intCast(index * 8)));
            }
        },
    }
    return @truncate(result);
}