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scan writing done

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This commit is contained in:
Muaz Ahmad 2023-12-07 14:33:27 +05:00
parent f074e99eca
commit eeb67c3b79
1 changed files with 66 additions and 10 deletions
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76
src/output.zig
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@ -40,20 +40,76 @@ const BitWriter = struct {
var i = idx_ptr.*;
defer idx_ptr.* = i;
try self.write_value(dc_huff.get(units[i].symbol).?, if (units[i].value >= 0) units[i].value else -units[i].value, units[i].symbol & 0x0f);
try self.write_value(dc_huff.get(units[i].symbol).?, units[i]);
i += 1;
while (units[i].symbol != 0x00) : (i += 1) {
try self.write_value(ac_huff.get(units[i].symbol).?, units[i].value, units[i].symbol & 0x0f);
try self.write_value(ac_huff.get(units[i].symbol).?, units[i]);
}
try self.write_value(ac_huff.get(units[i].symbol).?, units[i].value, units[i].symbol & 0x0f);
try self.write_value(ac_huff.get(units[i].symbol).?, units[i]);
i += 1;
}
fn write_value(self: *Self, huffcode: HuffCode, value: i16, val_bits: u8) !void {
_ = val_bits;
_ = value;
_ = huffcode;
_ = self;
fn write_value(self: *Self, huffcode: HuffCode, unit: RLE_Unit) !void {
try self.write_bits(huffcode.value, huffcode.n_bits);
const unit_val: u16 = if (unit.value >= 0) blk: {
break :blk @bitCast(unit.value);
} else blk: {
const tmp: u16 = @bitCast(unit.value - 1);
break :blk tmp & (try std.math.powi(u16, 2, unit.symbol & 0x0f) - 1);
};
try self.write_bits(unit_val, unit.symbol & 0x0f);
}
inline fn write_bits(self: *Self, val: u16, n_bits: u8) !void {
if (self.curr_bit_used + n_bits < 8) {
self.buff[self.curr_buff_idx] = @truncate((self.buff[self.curr_buff_idx] << @truncate(n_bits)) | val);
self.curr_bit_used += @truncate(n_bits);
} else {
const bits_align_n = 8 - self.curr_bit_used;
self.buff[self.curr_buff_idx] = @truncate((self.buff[self.curr_buff_idx] << @truncate(bits_align_n)) | (val >> @truncate(n_bits - bits_align_n)));
var byte_stuff_flag = self.buff[self.curr_buff_idx] == 0xff;
self.curr_bit_used = 0;
self.curr_buff_idx += 1;
try self.flush();
if (byte_stuff_flag) {
self.curr_buff_idx += 1;
try self.flush();
}
var bits_left = n_bits - bits_align_n;
var val_left = val & (try std.math.powi(u16, 2, bits_left) - 1);
while (bits_left >= 8) : (bits_left -= 8) {
self.buff[self.curr_buff_idx] = @truncate(val_left >> @truncate(bits_left - 8));
byte_stuff_flag = self.buff[self.curr_buff_idx] == 0xff;
val_left = val_left & (try std.math.powi(u16, 2, bits_left - 8) - 1);
self.curr_buff_idx += 1;
if (self.curr_buff_idx == self.buff.len) try self.flush();
if (byte_stuff_flag) {
self.curr_buff_idx += 1;
try self.flush();
}
}
self.buff[self.curr_buff_idx] = @truncate((self.buff[self.curr_buff_idx] << @truncate(bits_left)) | val_left);
self.curr_bit_used += @truncate(bits_left);
}
}
inline fn flush(self: *Self) !void {
if (self.curr_buff_idx == self.buff.len) {
_ = try self.f.write(&self.buff);
self.curr_buff_idx = 0;
@memset(&self.buff, 0);
}
}
inline fn flush_end(self: *Self) !void {
if (self.curr_bit_used != 0) {
const stuff_n = 8 - self.curr_bit_used;
self.buff[self.curr_buff_idx] = @truncate((self.curr_buff_idx << stuff_n) | (try std.math.powi(u8, 2, stuff_n) - 1));
self.curr_buff_idx += 1;
}
_ = try self.f.write(self.buff[0..self.curr_buff_idx]);
}
};
@ -128,7 +184,7 @@ const Scan = struct {
try bw.write_until_eob(self.rles[1].items, &idxs[1], &self.huffs[2], &self.huffs[3]);
try bw.write_until_eob(self.rles[2].items, &idxs[2], &self.huffs[2], &self.huffs[3]);
}
try bw.flush_end();
_ = try f.write(&[2]u8{ 0xff, 0xd9 });
}
};
@ -186,7 +242,7 @@ inline fn gen_codes(huff: *Huffman, huffman_meta: HuffmanMeta) !void {
j = 1;
}
huffsize[k] = 0;
const total_k = k + 1;
const total_k = k;
k = 0;
var code: usize = 0;