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add huffman boiler, Code_size impl

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Muaz Ahmad 2023-11-30 16:40:21 +05:00
parent 03e986b5d6
commit a25213fa2d
1 changed files with 64 additions and 0 deletions
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64
src/output.zig
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@ -58,9 +58,73 @@ const Scan = struct {
try parse_block(&buff.V_quant[x][y], &self.dc_diffs[2], &self.rles[2], self.freqs[2], self.freqs[3]);
}
}
try self.generate_huffmans();
}
fn generate_huffmans(self: *Self) !void {
for (0..4) |i| {
try gen_huffman(&self.huffs[i], self.freqs[i]);
}
}
};
inline fn get_idx_min2(freqs: []u32) ?struct { usize, usize } {
var min1: u32 = undefined;
var min1_idx: usize = undefined;
var min2: u32 = undefined;
var min2_idx: usize = undefined;
var is_init_1 = false;
var is_init_2 = false;
for (0..freqs.len) |i| {
if (freqs[i] == 0) continue;
if (!is_init_1) {
min1 = freqs[i];
min1_idx = i;
} else if (!is_init_2) {
if (freqs[i] < min1) {
min2 = min1;
min2_idx = min1_idx;
min1 = freqs[i];
min1_idx = i;
} else {
min2 = freqs[i];
min2_idx = i;
}
} else if (freqs[i] < min1) {
min1 = freqs[i];
min1_idx = i;
} else if (freqs[i] < min2) {
min2 = freqs[i];
min2_idx = i;
}
}
return if (is_init_2) .{
min1_idx,
min2_idx,
} else null;
}
inline fn gen_huffman(huff: *Huffman, freqs: []u32) !void {
_ = huff;
var codesizes = [_]u8{0} ** 257;
var others = [_]u9{0x1ff} ** 257;
while (get_idx_min2(freqs)) |tmp| {
var v1 = tmp.@"0";
var v2 = tmp.@"1";
freqs[v1] += freqs[v2];
codesizes[v1] += 1;
while (others[v1] != 0x1ff) : (codesizes[v1] += 1) {
v1 = others[v1];
}
others[v1] = @truncate(v2);
codesizes[v2] += 1;
while (others[v2] != 0x1ff) : (codesizes[v2] += 1) {
v2 = others[v2];
}
}
}
inline fn get_size(n: i16) u8 {
if (n == 0) {
return 0;