remove commented code

build.zig

@@ -46,6 +46,10 @@ pub fn build(b: *std.build.Builder) !void {
     exe.addIncludePath("lib/i2cdriver");
     exe.install();
 
+    // TODO: I believe we can use runArtifact on a second
+    // exe with a different source file for font generation
+    // taking us to a series of 5 byte arrays for each
+    // character in a font.
     exe.step.dependOn(&AsciiPrintableStep.create(b, .{ .path = "src/images" }).step);
     // exe.step.dependOn((try fontGeneration(b, target)));
     const run_cmd = exe.run();

lib/i2cdriver/i2cdriver.c

@@ -177,7 +177,13 @@ int readFromSerialPort(int fd, uint8_t *b, size_t s)
 
 void writeToSerialPort(int fd, const uint8_t *b, size_t s)
 {
-  write(fd, b, s);
+  if (write(fd, b, s) == -1){
+    printf("WRITE FAILED %u: ", (int)s);
+    int i;
+    for (i = 0; i < s; i++)
+      printf("%02x ", 0xff & b[i]);
+    printf("\n");
+  }
 #ifdef VERBOSE
   printf("WRITE %u: ", (int)s);
   int i;
@@ -526,7 +532,7 @@ int i2c_commands(I2CDriver *sd, int argc, char *argv[])
 
         i2c_monitor(sd, 1);
         printf("[Hit return to exit monitor mode]\n");
-        fgets(line, sizeof(line) - 1, stdin);
+        if (!fgets(line, sizeof(line) - 1, stdin)) return 1;
         i2c_monitor(sd, 0);
       }
       break;

src/main.zig

@@ -17,15 +17,20 @@ const HEIGHT = 64;
 const FONT_WIDTH = 5;
 const FONT_HEIGHT = 8;
 
-const CHARS_PER_LINE = 21; // 21 * 6 = 126 so we have 2px left over
+const CHARS_PER_LINE = 25; // 25 * 5 = 125 so we have 3px left over
+const BORDER_LEFT = 1; // 1 empty px left, 2 empty on right
 const LINES = 8;
 
 // Device specifications
 const PAGES = 8;
 
+var lines: [LINES]*const [:0]u8 = undefined;
+
 fn usage(args: [][]u8) !void {
-    const stderr = std.io.getStdErr();
-    try stderr.writer().print("usage: {s} <image file> <device>\n", .{args[0]}); // TODO: will need more
+    const writer = std.io.getStdErr().writer();
+    try writer.print("usage: {s} <device> [-bg <image file>] [-<num> text]...\n", .{args[0]});
+    try writer.print("\t-<num> text: line number and text to display\n", .{});
+    try writer.print("\te.g. \"-1 'hello world'\" will display \"hello world\" on line 1\n", .{});
     std.os.exit(1);
 }
 pub fn main() !void {
@@ -33,11 +38,11 @@ pub fn main() !void {
     //defer alloc.deinit();
     const args = try std.process.argsAlloc(alloc);
     defer std.process.argsFree(alloc, args);
-    if (args.len < 3) try usage(args);
+    if (args.len < 2) try usage(args);
     const prefix = "/dev/ttyUSB";
-    const device = try alloc.dupeZ(u8, args[2]);
+    const device = try alloc.dupeZ(u8, args[1]);
     defer alloc.free(device);
-    if (!std.mem.startsWith(u8, device, prefix)) try usage(args);
+    if (!std.mem.eql(u8, device, "-") and !std.mem.startsWith(u8, device, prefix)) try usage(args);
 
     // stdout is for the actual output of your application, for example if you
     // are implementing gzip, then only the compressed bytes should be sent to
@@ -47,11 +52,45 @@ pub fn main() !void {
     const stdout = bw.writer();
     defer bw.flush() catch unreachable; // don't forget to flush!
 
-    const filename = args[1];
-    try stdout.print("Converting {s}\n", .{filename});
+    var filename: [:0]u8 = @constCast("");
+    var b: [1]u8 = undefined;
+    const nothing: [:0]u8 = try std.fmt.bufPrintZ(&b, "", .{});
+    for (lines, 0..) |_, i| {
+        lines[i] = &nothing;
+    }
+    var is_filename = false;
+    var line_number: ?usize = null;
+    for (args, 0..) |arg, i| {
+        if (std.mem.eql(u8, "-bg", arg)) {
+            is_filename = true;
+            continue;
+        }
+        if (is_filename) {
+            filename = args[i]; // arg capture changes value...
+            break;
+        }
+        if ((arg[0] == '-' and arg.len > 1) and areDigits(arg[1..])) {
+            line_number = try std.fmt.parseInt(usize, arg[1..], 10);
+            continue;
+        }
+        if (line_number) |line| {
+            if (arg.len > CHARS_PER_LINE) {
+                try std.io.getStdErr().writer().print(
+                    "ERROR: text for line {d} has {d} chars, exceeding maximum length {d}\n",
+                    .{ line, arg.len, CHARS_PER_LINE },
+                );
+                std.os.exit(1);
+            }
+            std.debug.print("line {d} text: \"{s}\"\n", .{ line, arg });
+            lines[line] = &args[i];
+            line_number = null;
+            continue;
+        }
+    }
+
+    if (filename.len > 0) try stdout.print("Converting {s}\n", .{filename});
     var pixels: [WIDTH * HEIGHT]u8 = undefined;
-    try convertImage(alloc, filename, &pixels);
-    // try convertImage(alloc, filename, &pixels);
+    try convertImage(alloc, filename, &pixels, textForLine);
     try stdout.print("Sending pixels to display\n", .{});
     // var i: usize = 0;
     // while (i < HEIGHT) {
@@ -68,7 +107,17 @@ pub fn main() !void {
     // try stdout.print("Run `zig build test` to run the tests.\n", .{});
 }
 
+fn areDigits(bytes: []u8) bool {
+    for (bytes) |byte| {
+        if (!std.ascii.isDigit(byte)) return false;
+    }
+    return true;
+}
+
 fn sendPixels(pixels: []const u8, file: [:0]const u8, device_id: u8) !void {
+    if (std.mem.eql(u8, file, "-"))
+        return sendPixelsToStdOut(pixels);
+
     if (@import("builtin").os.tag != .linux)
         @compileError("Linux only please!");
 
@@ -80,6 +129,16 @@ fn sendPixels(pixels: []const u8, file: [:0]const u8, device_id: u8) !void {
     return error.LinuxNativeNotImplemented;
 }
 
+fn sendPixelsToStdOut(pixels: []const u8) !void {
+    const stdout_file = std.io.getStdOut().writer();
+    var bw = std.io.bufferedWriter(stdout_file);
+    const stdout = bw.writer();
+    defer bw.flush() catch unreachable; // don't forget to flush!
+    for (0..HEIGHT) |i| {
+        try stdout.print("{d:0>2}: {s}\n", .{ i, fmtSliceGreyscaleImage(pixels[(i * WIDTH)..((i + 1) * WIDTH)]) });
+    }
+}
+
 fn sendPixelsThroughI2CDriver(pixels: []const u8, file: [*:0]const u8, device_id: u8) !void {
     var pixels_write_command = [_]u8{0x00} ** ((WIDTH * PAGES) + 1);
     pixels_write_command[0] = 0x40;
@@ -141,7 +200,7 @@ fn packPixelsToDeviceFormat(pixels: []const u8, packed_pixels: []u8) void {
         const column = i % WIDTH;
         const page = i / WIDTH;
 
-        if (column == 0) std.debug.print("{d}: ", .{page});
+        // if (column == 0) std.debug.print("{d}: ", .{page});
         // pixel array will be 8x as "high" as the data array we are sending to
         // the device. So the device column above is only our starter
         // Display has 8 pages, which is a set of 8 pixels with LSB at top of page
@@ -172,8 +231,8 @@ fn packPixelsToDeviceFormat(pixels: []const u8, packed_pixels: []u8) void {
             (pixels[(6 + row) * WIDTH + column] & 0x01) << 6 |
             (pixels[(7 + row) * WIDTH + column] & 0x01) << 7;
 
-        std.debug.print("{s}", .{std.fmt.fmtSliceHexLower(&[_]u8{b.*})});
-        if (column == 127) std.debug.print("\n", .{});
+        // std.debug.print("{s}", .{std.fmt.fmtSliceHexLower(&[_]u8{b.*})});
+        // if (column == 127) std.debug.print("\n", .{});
 
         // Last 2 pages are yellow...16 pixels vertical
         // if (page == 6 or page == 7) b.* = 0xff;
@@ -212,7 +271,10 @@ fn reportMagickError(mw: ?*c.MagickWand) !void {
     defer description = @ptrCast([*c]u8, c.MagickRelinquishMemory(description));
     try std.io.getStdErr().writer().print("{s}\n", .{description});
 }
-fn convertImage(alloc: std.mem.Allocator, filename: [:0]u8, pixels: *[WIDTH * HEIGHT]u8) !void {
+fn textForLine(line: usize) []u8 {
+    return lines[line].*;
+}
+fn convertImage(alloc: std.mem.Allocator, filename: [:0]u8, pixels: *[WIDTH * HEIGHT]u8, text_fn: *const fn (usize) []u8) !void {
     _ = alloc;
     c.MagickWandGenesis();
     defer c.MagickWandTerminus();
@@ -223,8 +285,19 @@ fn convertImage(alloc: std.mem.Allocator, filename: [:0]u8, pixels: *[WIDTH * HE
 
     // Reading an image into ImageMagick is problematic if it isn't a bmp
     // as the library needs a bunch of dependencies available
-    // var status = c.MagickReadImage(mw, "logo:");
-    var status = c.MagickReadImage(mw, filename);
+    var status: c.MagickBooleanType = undefined;
+    if (filename.len > 0) {
+        status = c.MagickReadImage(mw, filename);
+    } else {
+        // TODO: if there is no background image AND
+        // we precompute monochrome bit patterns for our font
+        // we can completely avoid ImageMagick here. Even with
+        // a background we can do the conversion, then do our
+        // own text overlay after monochrome conversion.
+        // Faster and smaller binary (maybe multi-font support?)
+        const blob = @embedFile("images/blank.bmp");
+        status = c.MagickReadImageBlob(mw, blob, blob.len);
+    }
     if (status == c.MagickFalse) {
         if (!std.mem.eql(u8, filename[filename.len - 3 ..], "bmp"))
             try std.io.getStdErr().writer().print("File is not .bmp. That is probably the problem\n", .{});
@@ -275,18 +348,25 @@ fn convertImage(alloc: std.mem.Allocator, filename: [:0]u8, pixels: *[WIDTH * HE
     if (status == c.MagickFalse)
         return error.CouldNotSetExtent;
 
-    mw = try drawCharacter(
-        mw.?,
-        '4',
-        -5 * 3,
-        -8,
-    );
-    mw = try drawCharacter(
-        mw.?,
-        '2',
-        -5 * 4,
-        -8,
-    );
+    for (0..LINES) |i| {
+        const text = text_fn(i);
+        if (text.len == 0) continue;
+        // We have text!
+        const y: isize = FONT_HEIGHT * @intCast(isize, i);
+        var x: isize = BORDER_LEFT;
+        var left_spaces: isize = 0;
+        for (text) |ch| {
+            if (ch == ' ') {
+                left_spaces += 1;
+                continue;
+            }
+            break;
+        }
+        std.debug.print("left_spaces: {d}. Text: \"{s}\"\n", .{ left_spaces, text });
+        x += (FONT_WIDTH * left_spaces);
+        mw = try drawString(mw, text[@intCast(usize, left_spaces)..], x, y);
+    }
+
     // We make the image monochrome by quantizing the image with 2 colors in the
     // gray colorspace. See:
     // https://www.imagemagick.org/Usage/quantize/#monochrome
@@ -319,6 +399,18 @@ fn convertImage(alloc: std.mem.Allocator, filename: [:0]u8, pixels: *[WIDTH * HE
         }
     }
 }
+fn drawString(mw: ?*c.MagickWand, str: []const u8, x: isize, y: isize) !?*c.MagickWand {
+    var rc = mw;
+    for (str, 0..) |ch, i| {
+        rc = try drawCharacter(
+            rc,
+            ch,
+            -(x + @intCast(isize, FONT_WIDTH * i)),
+            -y,
+        );
+    }
+    return rc;
+}
 
 fn drawCharacter(mw: ?*c.MagickWand, char: u8, x: isize, y: isize) !?*c.MagickWand {
     // Create a second wand. Does this need to exist after the block?