basic bdf parsing

.gitignore

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+zig-cache
+zig-out
+*.bdf
+out
+*.font.zon

build.zig

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+const std = @import("std");
+
+// Although this function looks imperative, note that its job is to
+// declaratively construct a build graph that will be executed by an external
+// runner.
+pub fn build(b: *std.Build) void {
+    // Standard target options allows the person running `zig build` to choose
+    // what target to build for. Here we do not override the defaults, which
+    // means any target is allowed, and the default is native. Other options
+    // for restricting supported target set are available.
+    const target = b.standardTargetOptions(.{});
+
+    // Standard optimization options allow the person running `zig build` to select
+    // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
+    // set a preferred release mode, allowing the user to decide how to optimize.
+    const optimize = b.standardOptimizeOption(.{});
+
+    const exe = b.addExecutable(.{
+        .name = "binfon",
+        .root_source_file = b.path("src/main.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    b.installArtifact(exe);
+
+    const run_cmd = b.addRunArtifact(exe);
+    run_cmd.step.dependOn(b.getInstallStep());
+
+    if (b.args) |args| {
+        run_cmd.addArgs(args);
+    }
+
+    const run_step = b.step("run", "Run the app");
+    run_step.dependOn(&run_cmd.step);
+}

build.zig.zon

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+.{
+    .name = "binfon",
+    // This is a [Semantic Version](https://semver.org/).
+    // In a future version of Zig it will be used for package deduplication.
+    .version = "0.0.0",
+
+    // This field is optional.
+    // This is currently advisory only; Zig does not yet do anything
+    // with this value.
+    //.minimum_zig_version = "0.11.0",
+
+    // This field is optional.
+    // Each dependency must either provide a `url` and `hash`, or a `path`.
+    // `zig build --fetch` can be used to fetch all dependencies of a package, recursively.
+    // Once all dependencies are fetched, `zig build` no longer requires
+    // internet connectivity.
+    .dependencies = .{
+        // See `zig fetch --save <url>` for a command-line interface for adding dependencies.
+        //.example = .{
+        //    // When updating this field to a new URL, be sure to delete the corresponding
+        //    // `hash`, otherwise you are communicating that you expect to find the old hash at
+        //    // the new URL.
+        //    .url = "https://example.com/foo.tar.gz",
+        //
+        //    // This is computed from the file contents of the directory of files that is
+        //    // obtained after fetching `url` and applying the inclusion rules given by
+        //    // `paths`.
+        //    //
+        //    // This field is the source of truth; packages do not come from a `url`; they
+        //    // come from a `hash`. `url` is just one of many possible mirrors for how to
+        //    // obtain a package matching this `hash`.
+        //    //
+        //    // Uses the [multihash](https://multiformats.io/multihash/) format.
+        //    .hash = "...",
+        //
+        //    // When this is provided, the package is found in a directory relative to the
+        //    // build root. In this case the package's hash is irrelevant and therefore not
+        //    // computed. This field and `url` are mutually exclusive.
+        //    .path = "foo",
+
+        //    // When this is set to `true`, a package is declared to be lazily
+        //    // fetched. This makes the dependency only get fetched if it is
+        //    // actually used.
+        //    .lazy = false,
+        //},
+    },
+
+    // Specifies the set of files and directories that are included in this package.
+    // Only files and directories listed here are included in the `hash` that
+    // is computed for this package.
+    // Paths are relative to the build root. Use the empty string (`""`) to refer to
+    // the build root itself.
+    // A directory listed here means that all files within, recursively, are included.
+    .paths = .{
+        // This makes *all* files, recursively, included in this package. It is generally
+        // better to explicitly list the files and directories instead, to insure that
+        // fetching from tarballs, file system paths, and version control all result
+        // in the same contents hash.
+        "",
+        // For example...
+        //"build.zig",
+        //"build.zig.zon",
+        //"src",
+        //"LICENSE",
+        //"README.md",
+    },
+}

src/bdf.zig

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+const std = @import("std");
+
+const Bitmap = [][]u8;
+
+const Character = struct {
+    name: []u8,
+    bitmap: Bitmap,
+
+    pub fn deinit(self: *Character, allocator: std.mem.Allocator) void {
+        for (self.bitmap) |line| {
+            allocator.free(line);
+        }
+        allocator.free(self.bitmap);
+        allocator.free(self.name);
+    }
+};
+const CharacterMap = std.AutoHashMap(u16, Character);
+
+const Font = struct {
+    name: []const u8,
+    height: u8,
+    width: u8,
+    characters: CharacterMap,
+
+    pub fn deinit(self: *Font, allocator: std.mem.Allocator) void {
+        var iterator = self.characters.valueIterator();
+        while (iterator.next()) |char| {
+            char.deinit(allocator);
+        }
+        self.characters.deinit();
+    }
+};
+
+const Command = enum {
+    FONT,
+    FONTBOUNDINGBOX,
+    ENCODING,
+    BITMAP,
+    STARTCHAR,
+    _IGNORED,
+};
+
+const Line = struct {
+    command: Command,
+    params: []const u8,
+};
+
+pub fn parse(allocator: std.mem.Allocator, bdf: anytype) !Font {
+    var font: Font = .{
+        .name = undefined,
+        .height = 0,
+        .width = 0,
+        .characters = CharacterMap.init(allocator),
+    };
+
+    var bufferedReader = std.io.bufferedReader(bdf);
+    var reader = bufferedReader.reader();
+
+    var currentName: []const u8 = undefined;
+    var currentCharacter: u16 = 0;
+    while (true) {
+        var lineBuffer: [1024]u8 = undefined;
+        const nextLine = try reader.readUntilDelimiterOrEof(&lineBuffer, '\n') orelse break;
+
+        // Parse line
+        const line = try parseLine(nextLine);
+        switch (line.command) {
+            .FONT => {
+                font.name = line.params;
+                std.log.debug("Font: {s}", .{font.name});
+            },
+            .FONTBOUNDINGBOX => {
+                var boundingBox = std.mem.splitScalar(u8, line.params, ' ');
+                font.width = try std.fmt.parseInt(u8, boundingBox.next().?, 10);
+                font.height = try std.fmt.parseInt(u8, boundingBox.next().?, 10);
+
+                std.log.debug("Bounding box: {d}x{d}", .{ font.width, font.height });
+            },
+            .BITMAP => {
+                const bitmap = try readBitmap(allocator, font.width, font.height, reader);
+                try font.characters.put(currentCharacter, .{
+                    .name = try allocator.dupe(u8, currentName),
+                    .bitmap = bitmap,
+                });
+            },
+            .STARTCHAR => {
+                currentName = line.params;
+            },
+            .ENCODING => {
+                // This probably breaks with custom encodings, not doing anything for now
+                currentCharacter = try std.fmt.parseInt(u16, line.params, 10);
+            },
+            else => {},
+        }
+    }
+
+    return font;
+}
+
+fn parseLine(line: []const u8) !Line {
+    const firstSpace = std.mem.indexOfScalar(u8, line, ' ') orelse line.len;
+    const command = line[0..firstSpace];
+
+    return .{
+        .command = std.meta.stringToEnum(Command, command) orelse Command._IGNORED,
+        .params = if (firstSpace == line.len) "" else line[firstSpace + 1 ..],
+    };
+}
+
+fn readBitmap(
+    allocator: std.mem.Allocator,
+    width: u8,
+    height: u8,
+    reader: anytype,
+) !Bitmap {
+    var lineIndex: u8 = 0;
+
+    var char = try allocator.alloc([]u8, height);
+    errdefer {
+        for (0..lineIndex) |i| {
+            allocator.free(char[i]);
+        }
+        allocator.free(char);
+    }
+
+    // Allocate memory for the parsed bitmap
+    var line: []u8 = try allocator.alloc(u8, width / 8);
+    defer allocator.free(line);
+
+    // Read lines until ENDCHAR
+    while (true) {
+        std.debug.assert(lineIndex < height + 1);
+
+        // Read the next line
+        var lineBuffer: [128]u8 = undefined;
+        const nextLine = try reader.readUntilDelimiterOrEof(&lineBuffer, '\n') orelse break;
+
+        // If we encounter the magic string, we're done
+        if (std.mem.eql(u8, nextLine, "ENDCHAR")) {
+            break;
+        }
+
+        // Parse every 2 char as a hexadecimal number
+        var i: usize = 0;
+        while (i < nextLine.len) : (i += 2) {
+            const hex = try std.fmt.parseInt(u8, nextLine[i .. i + 2], 16);
+            line[i / 2] = hex;
+        }
+
+        // Copy over to the array (this memory must be freed later)
+        char[lineIndex] = try allocator.dupe(u8, line);
+        lineIndex += 1;
+    }
+
+    return char;
+}

src/main.zig

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+const std = @import("std");
+const bdf = @import("bdf.zig");
+
+pub fn main() !void {
+    // Get allocator
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    const allocator = gpa.allocator();
+    defer _ = gpa.deinit();
+
+    // Get args
+    const args = try std.process.argsAlloc(allocator);
+    defer std.process.argsFree(allocator, args);
+
+    if (args.len < 3) {
+        std.log.err("Usage: {s} <input.bdf> <input.zon> <output-dir>", .{args[0]});
+        std.process.exit(1);
+    }
+
+    const inputFile = args[1];
+    const outputPath = args[2];
+    _ = outputPath; // autofix
+
+    // Read font
+    const input = try std.fs.cwd().openFile(inputFile, .{});
+    defer input.close();
+
+    var font = try bdf.parse(allocator, input.reader());
+    defer font.deinit(allocator);
+}