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//! The font header.

use q32;

const MAGIC_NUMBER: u32 = 0x5F0F3CF5;

macro_rules! reject(() => (raise!("the font header is corrupted")));

table! {
    #[doc = "A font header."]
    #[derive(Copy)]
    pub FontHeader {
        version (q32) |tape, this| { // version
            let value = read_value!(tape);
            if value != q32(0x00010000) {
                raise!("the version of the font header is not supported");
            }
            Ok(value)
        },

        revision            (q32), // fontRevision
        checksum_adjustment (u32), // checkSumAdjustment

        magic_number (u32) |tape, this| { // MagicNumber
            let value = read_value!(tape);
            if value != MAGIC_NUMBER {
                reject!();
            }
            Ok(value)
        },

        flags (Flags) |tape, this| { // flags
            let value = read_value!(tape, Flags);
            if value.is_invalid() {
                reject!();
            }
            Ok(value)
        },

        units_per_em          (u16), // unitsPerEm
        created               (i64), // created
        modified              (i64), // modified
        min_x                 (i16), // xMin
        min_y                 (i16), // yMin
        max_x                 (i16), // xMax
        max_y                 (i16), // yMax
        mac_style             (u16), // macStyle
        lowest_ppem           (u16), // lowestRecPPEM
        direction_hint        (i16), // fontDirectionHint
        glyph_location_format (i16), // indexToLocFormat
        glyph_data_format     (i16), // glyphDataFormat
    }
}

flags! {
    #[doc = "Flags of a font header."]
    pub Flags(u16) {
        0b0000_0000_0000_0001 => is_baseline_at_0,
        0b0000_0000_0000_0010 => is_left_sidebearing_at_0,
        0b1000_0000_0000_0000 => is_invalid,
    }
}