basic zig working
This commit is contained in:
parent
6264dd9e87
commit
8820f239b8
487
src/main.zig
487
src/main.zig
@ -80,6 +80,25 @@ fn HuffmanGraph(comptime valueType: type) type {
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}
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return d + 1;
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}
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fn valid(self: *NodeSelf) bool {
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var has_child = self.right == null and self.left == null;
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if (self.value != null)
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return has_child;
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if (has_child)
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return false;
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if (self.right) |r|
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if (!r.valid())
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return false;
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if (self.left) |l|
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if (!l.valid())
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return false;
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return true;
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}
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};
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root: *Node,
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@ -100,14 +119,15 @@ fn HuffmanGraph(comptime valueType: type) type {
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}
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fn print(self: *Self) void {
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for (0..(self.depth() + 1)) |i| {
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var d = self.depth() + 1;
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for (0..d) |i| {
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self.root.print(0, i);
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utils.printf("\n", .{});
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}
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}
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fn addValue(self: *Self, code: u64, size: u8, value: valueType) !void {
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var walker = try BitWalkerUint(u64, true).init(code, size);
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fn addValue(self: *Self, code: u64, size: usize, value: valueType) !void {
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var walker = try BitWalkerUint(u64).init(code, size, true);
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var curNode: *Node = self.root;
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@ -166,78 +186,206 @@ fn HuffmanGraph(comptime valueType: type) type {
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return error.InvalidBitSequence;
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}
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fn nextBitW(self: *Self, bitw: *BitWalker) !valueType {
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while (true) {
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if (try self.iter(try bitw.bitWalk())) |value|
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return value;
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}
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}
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fn valid(self: *Self) bool {
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return self.root.valid();
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}
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fn deinit(self: *Self) void {
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self.root.deinit();
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}
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};
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}
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const DynamicDecoder = struct {
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const Self = @This();
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fn create_dynamic_graph(walker: *BitWalker, len_to_read: usize, allocator: mem.Allocator) !HuffmanGraph(u64) {
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const list: [19]u8 = .{ 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
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len_to_read: usize,
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codes: [19]u64,
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walker: *BitWalker,
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allocator: mem.Allocator,
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graph: HuffmanGraph(u64),
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const lens: []u8 = try allocator.alloc(u8, 19);
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defer allocator.free(lens);
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mem.set(u8, lens, 0);
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fn init(walker: *BitWalker, len_to_read: usize, allocator: mem.Allocator) !Self {
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const list: [19]u8 = .{ 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
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var lenList: [19]u3 = .{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
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var bl_count: [7]u3 = .{ 0, 0, 0, 0, 0, 0, 0 };
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var max: u8 = 0;
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for (0..len_to_read) |i| {
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var data: u3 = @intCast(u3, try walker.walk(3));
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lenList[i] = data;
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if (data == 0) {
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continue;
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}
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bl_count[data] += 1;
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if (data > max) {
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max = data;
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}
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}
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var next_code: [19]u64 = .{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
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var code: u64 = 0;
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for (1..(max + 1)) |bits| {
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code = @shlExact(code + bl_count[bits - 1], 1);
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next_code[bits] = code;
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}
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var codes: [19]u64 = .{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
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for (0..19) |n| {
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var len = lenList[n];
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if (len != 0) {
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codes[n] = next_code[len];
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next_code[len] += 1;
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}
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}
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var graph = try HuffmanGraph(u64).init(allocator);
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for (0..19) |i| {
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if (lenList[i] == 0)
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continue;
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try graph.addValue(codes[i], lenList[i], list[i]);
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}
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return .{
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.len_to_read = len_to_read,
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.codes = codes,
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.walker = walker,
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.allocator = allocator,
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.graph = graph,
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};
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for (0..len_to_read) |i| {
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lens[list[i]] = @intCast(u8, try walker.walk(3));
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}
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fn deinit(self: *Self) void {
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self.graph.deinit();
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var builder = try GraphBuilder(u64).init(allocator, 19, 0, 8);
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defer builder.deinit();
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while (!builder.done()) {
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builder.addValue(builder.i, lens[builder.i]);
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}
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};
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return try builder.build();
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}
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fn GraphBuilder(comptime T: type) type {
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return struct {
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const Self = @This();
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allocator: mem.Allocator,
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values: []T,
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lens: []usize,
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bl_count: []usize,
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size: usize,
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max: usize = 0,
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i: usize = 0,
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pub fn init(allocator: mem.Allocator, size: usize, default: T, maxlen: usize) !Self {
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var values = try allocator.alloc(T, size);
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mem.set(T, values, default);
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var lens = try allocator.alloc(usize, size);
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mem.set(usize, lens, 0);
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var bl_count = try allocator.alloc(usize, maxlen);
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mem.set(usize, bl_count, 0);
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return Self{
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.allocator = allocator,
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.bl_count = bl_count,
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.size = size,
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.values = values,
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.lens = lens,
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};
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}
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pub fn skip(self: *Self, len: usize) void {
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self.i += len;
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}
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pub fn done(self: *Self) bool {
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return self.i >= self.size;
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}
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pub fn addValue(self: *Self, value: T, len: usize) void {
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if (len > self.max) {
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self.max = len;
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}
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self.values[self.i] = value;
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self.lens[self.i] = len;
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self.bl_count[len] += 1;
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self.i += 1;
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}
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pub fn build(self: *Self) !HuffmanGraph(T) {
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self.bl_count[0] = 0;
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var next_code = try self.allocator.alloc(usize, self.max + 1);
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defer self.allocator.free(next_code);
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std.mem.set(usize, next_code, 0);
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var code: usize = 0;
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for (1..(self.max + 1)) |bits| {
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code = @shlExact(code + self.bl_count[bits - 1], 1);
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next_code[bits] = code;
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}
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var codes = try self.allocator.alloc(u64, self.size);
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defer self.allocator.free(codes);
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std.mem.set(usize, codes, 0);
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for (0..self.size) |n| {
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var len = self.lens[n];
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if (len != 0) {
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codes[n] = next_code[len];
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next_code[len] += 1;
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}
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}
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var graph = try HuffmanGraph(T).init(self.allocator);
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errdefer graph.deinit();
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for (0..self.size) |i| {
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if (self.lens[i] == 0)
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continue;
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try graph.addValue(codes[i], self.lens[i], self.values[i]);
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}
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if (!graph.valid())
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return error.graph_not_valid;
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return graph;
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}
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pub fn buildWithDynamic(self: *Self, bitw: *BitWalker, graph: *HuffmanGraph(u64)) !HuffmanGraph(T) {
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while (!self.done()) {
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var v = try graph.nextBitW(bitw);
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if (v == 16) {
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return error.not_implemented;
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} else if (v == 17) {
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self.skip(try bitw.walk(3) + 3);
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} else if (v == 18) {
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self.skip(try bitw.walk(7) + 11);
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} else {
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self.addValue(self.i, v);
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}
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}
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return try self.build();
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}
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pub fn deinit(self: *Self) void {
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self.allocator.free(self.values);
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self.allocator.free(self.lens);
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self.allocator.free(self.bl_count);
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}
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};
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}
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fn get_len_value(bitw: *BitWalker, len_code: usize) !usize {
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var extra_bits: usize = switch (len_code) {
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257...264 => 0,
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265...268 => 1,
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269...272 => 2,
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273...277 => 3,
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278...280 => 4,
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281...284 => 5,
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285 => 0,
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else => unreachable,
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};
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var to_add = try bitw.walk(extra_bits);
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var base_value: usize = switch (len_code) {
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257...264 => 3 + len_code - 257,
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265...268 => 11 + (len_code - 265) * 2,
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269...272 => 19 + (len_code - 269) * 3,
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273...277 => 35 + (len_code - 273) * 7,
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278...280 => 67 + (len_code - 278) * 15,
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281...284 => 131 + (len_code - 281) * 31,
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285 => 0,
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else => unreachable,
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};
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return base_value + to_add;
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}
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fn get_dist_value(bitw: *BitWalker, dist_graph: *HuffmanGraph(u64)) !usize {
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var dist = try dist_graph.nextBitW(bitw);
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var extra_bits: usize = switch (dist) {
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0...3 => 0,
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4...29 => (dist / 2) - 1,
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else => unreachable,
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};
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var to_add = try bitw.walk(extra_bits);
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var base_value: usize = switch (dist) {
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0...3 => dist + 1,
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4...29 => std.math.pow(usize, 2, dist / 2) + (std.math.pow(usize, 2, (dist / 2) - 1) * (dist % 2)) + 1,
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else => unreachable,
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};
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return base_value + to_add;
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}
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const BlockData = struct {
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const Self = @This();
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@ -248,63 +396,157 @@ const BlockData = struct {
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last: bool,
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blockType: u8,
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fn init(allocator: mem.Allocator, bitw: *BitWalker) !Self {
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literal_graph: ?HuffmanGraph(u64) = null,
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dist_graph: ?HuffmanGraph(u64) = null,
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output: *[]u8,
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fn init(allocator: mem.Allocator, bitw: *BitWalker, output: *[]u8) !Self {
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return Self{
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.bitw = bitw,
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.allocator = allocator,
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.last = try bitw.walk(1) == 1,
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.blockType = try bitw.walk(2),
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.blockType = @intCast(u8, try bitw.walk(2)),
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.output = output,
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};
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}
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fn uncompress(self: *Self) !void {
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if (self.blockType != 2) {
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return error.unsuported_block_type;
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}
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try self.dynamic_huffman();
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fn uncompress(self: *Self, start_place: usize) !usize {
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return switch (self.blockType) {
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1 => blk: {
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try self.fixed();
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break :blk 0;
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},
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2 => self.dynamic_huffman(start_place),
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3 => error.block_type_error,
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else => unreachable,
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};
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}
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fn dynamic_huffman(self: *Self) !void {
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fn fixed(self: *Self) !void {
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var litBuilder = try GraphBuilder(u64).init(self.allocator, 287, 0, 10);
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defer litBuilder.deinit();
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for (0..144) |i| {
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//try lit.addValue(0b00110000 + i, 8, i);
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litBuilder.addValue(i, 8);
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}
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for (144..256) |i| {
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//try lit.addValue(0b001100000 + i, 9, i);
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litBuilder.addValue(i, 9);
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}
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for (256..280) |i| {
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//try lit.addValue(0b0000000 + i, 7, i);
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litBuilder.addValue(i, 7);
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}
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for (280..287) |i| {
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litBuilder.addValue(i, 8);
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//try lit.addValue(0b11000000 + i, 8, i);
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}
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var lit = try litBuilder.build();
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self.literal_graph = lit;
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lit.print();
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// var dist = try HuffmanGraph(u64).init(self.allocator);
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// for (0..144) |i| {
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// try lit.addValue(0b00110000 + i, 8, i);
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// }
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// for (144..256) |i| {
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// try lit.addValue(0b001100000 + i, 9, i);
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// }
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// for (256..280) |i| {
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// try lit.addValue(0b0000000 + i, 7, i);
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// }
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// for (280..287) |i| {
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// try lit.addValue(0b11000000 + i, 8, i);
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// }
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// self.literal_graph = lit;
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//TODO dist
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var bitw = self.bitw;
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var number_of_literal_codes: u32 = @as(u32, try bitw.walk(5)) + 257;
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var number_of_dist_codes = try bitw.walk(5) + 1;
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var number_of_length_codes = try bitw.walk(4) + 4;
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print("number of literal codes: {}", .{number_of_literal_codes});
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print("number of dist codes: {}", .{number_of_dist_codes});
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print("number_of_length_codes: {}", .{number_of_length_codes});
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var dynamic_decoder = try DynamicDecoder.init(bitw, number_of_length_codes, self.allocator);
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defer dynamic_decoder.deinit();
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dynamic_decoder.graph.print();
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var code_len: usize = 0;
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while (code_len < number_of_literal_codes) {
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var decode_value = try dynamic_decoder.graph.iter(try bitw.bitWalk());
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while (decode_value == null) {
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decode_value = try dynamic_decoder.graph.iter(try bitw.bitWalk());
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}
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print("Test {any}", .{decode_value});
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if (decode_value.? == 16) {
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while (true) {
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var lastRead = try lit.nextBitW(bitw);
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if (lastRead == 256) {
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break;
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} else if (lastRead > 256) {
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utils.printf("❓({})", .{lastRead});
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//var dist = try self.dist_graph.?.nextBitW(bitw);
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//utils.printf("<{}>", .{dist});
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return error.not_implemented;
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} else if (decode_value.? == 17) {
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code_len += try bitw.walk(3);
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} else if (decode_value.? == 18) {
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code_len += try bitw.walk(7);
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} else if (lastRead < 256) {
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utils.printf("{c}", .{@intCast(u8, lastRead)});
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} else {
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code_len += 1;
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unreachable;
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}
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}
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return error.todo;
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}
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fn read_len_code() void {}
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fn dynamic_huffman(self: *Self, start_place: usize) !usize {
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var bitw = self.bitw;
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var number_of_literal_codes: u32 = @intCast(u32, try bitw.walk(5)) + 257;
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var number_of_dist_codes = try bitw.walk(5) + 1;
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var number_of_length_codes = try bitw.walk(4) + 4;
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var dynamic_graph = try create_dynamic_graph(bitw, number_of_length_codes, self.allocator);
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defer dynamic_graph.deinit();
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var builder = try GraphBuilder(u64).init(self.allocator, number_of_literal_codes, 0, 16);
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// destory either the 1st or the 2nd graph
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defer builder.deinit();
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self.literal_graph = try builder.buildWithDynamic(bitw, &dynamic_graph);
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var graph = self.literal_graph.?;
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// Destory the first builder
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builder.deinit();
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builder = try GraphBuilder(u64).init(self.allocator, number_of_dist_codes, 0, 16);
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self.dist_graph = try builder.buildWithDynamic(bitw, &dynamic_graph);
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var lastRead: u64 = 0;
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var i: usize = start_place;
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while (true) {
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lastRead = try graph.nextBitW(bitw);
|
||||
if (lastRead == 256) {
|
||||
break;
|
||||
} else if (lastRead > 256) {
|
||||
var len = try get_len_value(bitw, lastRead);
|
||||
var dist = try get_dist_value(bitw, &self.dist_graph.?);
|
||||
|
||||
var pos: usize = i - dist;
|
||||
for (0..len) |j| {
|
||||
self.output.ptr[i] = self.output.ptr[pos + j];
|
||||
i += 1;
|
||||
}
|
||||
} else if (lastRead < 256) {
|
||||
self.output.ptr[i] = @intCast(u8, lastRead);
|
||||
i += 1;
|
||||
} else {
|
||||
unreachable;
|
||||
}
|
||||
}
|
||||
|
||||
return i;
|
||||
}
|
||||
|
||||
fn deinit(self: *Self) void {
|
||||
if (self.literal_graph != null) {
|
||||
self.literal_graph.?.deinit();
|
||||
}
|
||||
if (self.dist_graph != null) {
|
||||
self.dist_graph.?.deinit();
|
||||
}
|
||||
}
|
||||
};
|
||||
|
||||
const LOCAL_FILE_HEADER_SIGNATURE = 0x04034b50;
|
||||
@ -366,10 +608,10 @@ const ZipFileHeader = struct {
|
||||
}
|
||||
|
||||
fn extract(self: *Self) !void {
|
||||
if (self.decompressed) {
|
||||
return error.AlreadyDecompressed;
|
||||
}
|
||||
// already decompressed
|
||||
if (self.decompressed) return;
|
||||
|
||||
// already decompressed
|
||||
if (self.compression_method == 0) {
|
||||
return error.uncompressed_file;
|
||||
}
|
||||
@ -380,19 +622,22 @@ const ZipFileHeader = struct {
|
||||
|
||||
self.uncompressed_content = try self.allocator.alloc(u8, self.uncompressed_size);
|
||||
errdefer self.allocator.free(self.uncompressed_content);
|
||||
mem.set(u8, self.uncompressed_content, 0);
|
||||
|
||||
var bitw = BitWalker.init(&self.compressed_content, false);
|
||||
var bitw = try BitWalker.init(&self.compressed_content);
|
||||
|
||||
var block = try BlockData.init(self.allocator, &bitw);
|
||||
var is_last = false;
|
||||
var output_place: usize = 0;
|
||||
|
||||
if (block.last) {
|
||||
print("last block", .{});
|
||||
} else {
|
||||
print("not last block", .{});
|
||||
while (!is_last) {
|
||||
var block = try BlockData.init(self.allocator, &bitw, &self.uncompressed_content);
|
||||
defer block.deinit();
|
||||
|
||||
is_last = block.last;
|
||||
|
||||
output_place = try block.uncompress(output_place);
|
||||
}
|
||||
|
||||
try block.uncompress();
|
||||
|
||||
self.decompressed = true;
|
||||
}
|
||||
|
||||
@ -460,14 +705,12 @@ pub fn main() !void {
|
||||
exit("Invalid file provided", .{}, 1);
|
||||
}
|
||||
|
||||
print("H: {}", .{first_file.compression_method});
|
||||
while (true) {
|
||||
var second_file = try ZipFileHeader.init(allocator, reader);
|
||||
defer second_file.deinit();
|
||||
|
||||
var second_file = try ZipFileHeader.init(allocator, reader);
|
||||
defer second_file.deinit();
|
||||
|
||||
try second_file.extract();
|
||||
|
||||
print("G: {s}", .{second_file.file_name});
|
||||
print("GI: {}", .{second_file.compression_method});
|
||||
print("xml stuff:\n{s}", .{second_file.compressed_content});
|
||||
try second_file.extract();
|
||||
print("G: {s}", .{second_file.file_name});
|
||||
print("xml stuff:\n{s}", .{second_file.uncompressed_content});
|
||||
}
|
||||
}
|
||||
|
||||
151
src/walker.zig
151
src/walker.zig
@ -1,7 +1,7 @@
|
||||
const std = @import("std");
|
||||
const utils = @import("utils.zig");
|
||||
|
||||
pub fn BitWalkerUint(comptime T: anytype, comptime reverse: bool) type {
|
||||
pub fn BitWalkerUint(comptime T: anytype) type {
|
||||
const typeInfo = @typeInfo(T);
|
||||
|
||||
if (typeInfo != .Int) {
|
||||
@ -18,15 +18,16 @@ pub fn BitWalkerUint(comptime T: anytype, comptime reverse: bool) type {
|
||||
|
||||
// TODO this is probably wrong
|
||||
in_byte_position: i16,
|
||||
size: u8,
|
||||
size: usize,
|
||||
reverse: bool,
|
||||
|
||||
const Self = @This();
|
||||
|
||||
pub fn init(value: T, size: u8) !Self {
|
||||
pub fn init(value: T, size: usize, reverse: bool) !Self {
|
||||
if (typeInfo.Int.bits < size)
|
||||
return error.invlaid_size;
|
||||
|
||||
var start_value: u8 = 0;
|
||||
var start_value: usize = 0;
|
||||
if (reverse) {
|
||||
start_value = size - 1;
|
||||
}
|
||||
@ -39,9 +40,10 @@ pub fn BitWalkerUint(comptime T: anytype, comptime reverse: bool) type {
|
||||
|
||||
return Self{
|
||||
.value = value,
|
||||
.in_byte_position = start_value,
|
||||
.in_byte_position = @intCast(i16, start_value),
|
||||
.size = size,
|
||||
.mask = mask,
|
||||
.reverse = reverse,
|
||||
};
|
||||
}
|
||||
|
||||
@ -51,7 +53,9 @@ pub fn BitWalkerUint(comptime T: anytype, comptime reverse: bool) type {
|
||||
|
||||
var result = (self.value & self.mask) == self.mask;
|
||||
|
||||
if (reverse) {
|
||||
//utils.print("walkbit: {b:08} & {b:08} -> {b:08} ({})", .{ self.value, self.mask, self.value & self.mask, result });
|
||||
|
||||
if (self.reverse) {
|
||||
self.in_byte_position -= 1;
|
||||
if (self.mask == 1) {
|
||||
self.mask = 0;
|
||||
@ -60,11 +64,10 @@ pub fn BitWalkerUint(comptime T: anytype, comptime reverse: bool) type {
|
||||
}
|
||||
} else {
|
||||
self.in_byte_position += 1;
|
||||
self.mask = @shlExact(self.mask, 1);
|
||||
if (self.in_byte_position > self.size) {
|
||||
if (self.in_byte_position >= self.size) {
|
||||
self.mask = 0;
|
||||
} else {
|
||||
self.mask = @shrExact(self.mask, 1);
|
||||
self.mask = @shlExact(self.mask, 1);
|
||||
}
|
||||
}
|
||||
|
||||
@ -77,77 +80,79 @@ pub const BitWalker = struct {
|
||||
const Self = @This();
|
||||
|
||||
data: *[]u8,
|
||||
position: usize = 0,
|
||||
in_byte_position: u3 = 0,
|
||||
direction: bool = false,
|
||||
|
||||
pub fn init(data: *[]u8, direction: bool) Self {
|
||||
// True == most Significant
|
||||
// False == least Significant
|
||||
direction: bool = false,
|
||||
unitWaker: BitWalkerUint(u8),
|
||||
position: usize,
|
||||
|
||||
pub fn init(data: *[]u8) !Self {
|
||||
return Self{
|
||||
.data = data,
|
||||
.direction = direction,
|
||||
.position = 0,
|
||||
.unitWaker = try BitWalkerUint(u8).init(data.ptr[0], 8, false),
|
||||
};
|
||||
}
|
||||
|
||||
pub fn change_direction(self: *Self) !void {
|
||||
self.direction = !self.direction;
|
||||
if (self.unitWaker.mask == 0)
|
||||
self.position += 1;
|
||||
// TODO probs wrong when mask != 0
|
||||
self.unitWaker = try BitWalkerUint(u8).init(self.data.ptr[self.position], 8, self.direction);
|
||||
}
|
||||
|
||||
pub fn smart_change_direction(self: *Self) !void {
|
||||
self.direction = !self.direction;
|
||||
if (self.unitWaker.mask == 0) {
|
||||
self.position += 1;
|
||||
self.unitWaker = try BitWalkerUint(u8).init(self.data.ptr[self.position], 8, self.direction);
|
||||
return;
|
||||
}
|
||||
if (!self.direction) {
|
||||
self.unitWaker = try BitWalkerUint(u8).init(self.data.ptr[self.position], 8, self.direction);
|
||||
} else {
|
||||
self.unitWaker = try BitWalkerUint(u8).init(self.data.ptr[self.position], 8, self.direction);
|
||||
}
|
||||
}
|
||||
|
||||
pub fn nextByte(self: *Self) !void {
|
||||
self.position += 1;
|
||||
self.unitWaker = try BitWalkerUint(u8).init(self.data.ptr[self.position], 8, self.direction);
|
||||
}
|
||||
|
||||
pub fn status(self: *Self) void {
|
||||
utils.print("p: {}, in: {} ({b:08})", .{ self.position, self.unitWaker.in_byte_position, self.unitWaker.mask });
|
||||
}
|
||||
|
||||
pub fn walk(self: *Self, bits: usize) !u64 {
|
||||
var number: u64 = 0;
|
||||
|
||||
//utils.print("walk: {}", .{bits});
|
||||
|
||||
var i: usize = 1;
|
||||
while (i <= bits) : (i += 1) {
|
||||
//utils.print("p: {}, in_p: {}", .{ self.position, self.unitWaker.in_byte_position });
|
||||
if (self.unitWaker.walkBit()) |next_number| {
|
||||
if (self.direction) {
|
||||
number = @shlExact(number, 1);
|
||||
number += next_number;
|
||||
} else {
|
||||
number += @shlExact(@as(u64, next_number), @intCast(u6, i - 1));
|
||||
}
|
||||
} else {
|
||||
try self.nextByte();
|
||||
i -= 1;
|
||||
}
|
||||
}
|
||||
|
||||
//utils.print("result: {} ({b:08})", .{ number, number });
|
||||
|
||||
return number;
|
||||
}
|
||||
|
||||
pub fn bitWalk(self: *Self) !u1 {
|
||||
return @intCast(u1, try self.walk(1));
|
||||
}
|
||||
|
||||
// TODO direction
|
||||
pub fn walk(self: *Self, bits: u3) !u8 {
|
||||
if (bits > 8 or bits == 0) return error.invalid_bit_number;
|
||||
|
||||
var byte = self.data.ptr[self.position];
|
||||
|
||||
// jumps over bytes
|
||||
if (self.in_byte_position + @as(u4, bits) > 8) {
|
||||
// Generate a mast that covers the last part of the old byte
|
||||
var old_mask: u8 = 0;
|
||||
var i: usize = 0;
|
||||
while (i < 8 - @as(u4, self.in_byte_position)) : (i += 1) {
|
||||
old_mask = @shlExact(old_mask, 1) + 1;
|
||||
}
|
||||
old_mask = @shlExact(old_mask, self.in_byte_position);
|
||||
|
||||
var next_byte = self.data.ptr[self.position + 1];
|
||||
var new_byte_pos: u3 = @intCast(u3, @as(u4, bits) - (8 - @as(u4, self.in_byte_position)));
|
||||
|
||||
var new_mask: u8 = 0;
|
||||
var j: usize = 0;
|
||||
while (j < new_byte_pos) : (j += 1) {
|
||||
new_mask = @shlExact(new_mask, 1) + 1;
|
||||
}
|
||||
|
||||
var result = @shrExact(byte & old_mask, self.in_byte_position) + @shlExact(next_byte & new_mask, @intCast(u3, 8 - @as(u4, self.in_byte_position)));
|
||||
|
||||
//print("mask: {b}, new_mask: {b}", .{ old_mask, new_mask });
|
||||
//print("here {b} {b}", .{ byte, old_mask });
|
||||
//print("here_new {b} {b}", .{ next_byte, new_mask });
|
||||
//print("result {}", .{result});
|
||||
|
||||
self.position += 1;
|
||||
self.in_byte_position = new_byte_pos;
|
||||
|
||||
return result;
|
||||
}
|
||||
|
||||
// Generate a mast that covers the last part of the old byte
|
||||
var old_mask: u8 = 0;
|
||||
var i: usize = 0;
|
||||
while (i < bits) : (i += 1) {
|
||||
old_mask = @shlExact(old_mask, 1) + 1;
|
||||
}
|
||||
old_mask = @shlExact(old_mask, self.in_byte_position);
|
||||
|
||||
const result = @shrExact(byte & old_mask, self.in_byte_position);
|
||||
|
||||
const sum = @intCast(u4, self.in_byte_position) + @intCast(u4, bits);
|
||||
if (sum == 8) {
|
||||
self.position += 1;
|
||||
self.in_byte_position = 0;
|
||||
} else {
|
||||
self.in_byte_position += bits;
|
||||
}
|
||||
|
||||
return result;
|
||||
}
|
||||
};
|
||||
|
||||
Loading…
Reference in New Issue
Block a user