From e398295a2beee67ca90fb536398c638b3df73459 Mon Sep 17 00:00:00 2001
From: Nathan Reiner <nathan@nathanreiner.xyz>
Date: Thu, 26 Mar 2026 10:14:09 +0100
Subject: jpeg: add segments

---
 src/jpg/frame.zig | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 src/jpg/frame.zig

(limited to 'src/jpg/frame.zig')

diff --git a/src/jpg/frame.zig b/src/jpg/frame.zig
new file mode 100644
index 0000000..35a6e8e
--- /dev/null
+++ b/src/jpg/frame.zig
@@ -0,0 +1,50 @@
+const std = @import("std");
+
+const Self = @This();
+
+pub const Component = packed struct(u24) {
+    identifier: u8,
+    horizontal_sampling_factor: u4,
+    vertical_sampling_factor: u4,
+    quantization_table_destination_selector: u8,
+};
+
+index: usize,
+sample_precision: u8,
+number_of_lines: u16,
+samples_per_line: u16,
+components: []Component,
+
+
+pub fn read(
+    gpa: std.mem.Allocator,
+    index: usize,
+    reader: *std.Io.Reader,
+) !Self {
+    var self: Self = undefined;
+
+    self.index = index;
+    self.sample_precision = try reader.takeByte();
+    self.number_of_lines = try reader.takeInt(u16, .big);
+    self.samples_per_line = try reader.takeInt(u16, .big);
+
+    const number_of_components = try reader.takeByte();
+
+    self.components = try gpa.alloc(Component, number_of_components);
+    errdefer gpa.free(self.components);
+
+    for (self.components) |*component| {
+        component.identifier = try reader.takeByte();
+        const sampling = try reader.takeByte();
+        component.horizontal_sampling_factor = @truncate(sampling >> 4);
+        component.vertical_sampling_factor = @truncate(sampling);
+        component.quantization_table_destination_selector = try reader.takeByte();
+    }
+
+    return self;
+}
+
+pub fn deinit(self: *Self, gpa: std.mem.Allocator) void {
+    gpa.free(self.components);
+    self.* = undefined;
+}
-- 
cgit v1.2.3-70-g09d2