| // Copyright 2026 The Wuffs Authors. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // https://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| // |
| // SPDX-License-Identifier: Apache-2.0 OR MIT |
| |
| pri func decoder.copy_partitions_to_workbuf?(src: base.io_reader, workbuf: slice base.u8) { |
| var i : base.u64 |
| var j : base.u64 |
| var n : base.u32 |
| |
| i = this.workbuf_yuv_v_end |
| j = this.workbuf_yuv_v_end + (this.partitioned_data_length as base.u64) |
| |
| while i < j, |
| inv j <= 0x20FF_FFF7, |
| { |
| if j > args.workbuf.length() { |
| return base."#bad workbuf length" |
| } |
| assert j > i via "a > b: b < a"() |
| n = args.src.limited_copy_u32_to_slice!( |
| up_to: ((j - i) & 0xFFFF_FFFF) as base.u32, |
| s: args.workbuf[i .. j]) |
| i ~mod+= n as base.u64 |
| if i < j { |
| yield? base."$short read" |
| } |
| } |
| |
| // Write eight 0x00 bytes to the end of the workbuf, past what we copy from |
| // args.src. Later on, we can then always peek_u64le from the workbuf. |
| |
| j += 8 |
| while i < j { |
| assert i < 0xFFFF_FFFF_FFFF_FFFF via "a < b: a < c; c <= b"(c: j) |
| if i >= args.workbuf.length() { |
| return base."#bad workbuf length" |
| } |
| args.workbuf[i] = 0x00 |
| i += 1 |
| } |
| } |
| |
| pri func decoder.decode_first_partition!(workbuf: roslice base.u8) base.status { |
| var v1 : base.u32[..= 1] |
| var v32 : base.u32 |
| |
| // RFC 6386 Section 9.2. Color Space and Pixel Type (Key Frames Only). |
| if this.is_key_frame { |
| this.read_bit!(workbuf: args.workbuf, part: 0, prob: 128) |
| this.read_bit!(workbuf: args.workbuf, part: 0, prob: 128) |
| } |
| |
| // RFC 6386 Section 9.3. Segment-Based Adjustments. |
| this.decode_segment_header!(workbuf: args.workbuf) |
| |
| // RFC 6386 Section 9.4. Loop Filter Type and Levels. |
| this.decode_filter_header!(workbuf: args.workbuf) |
| |
| // RFC 6386 Section 9.5. Token Partition and Partition Data Offsets. |
| v32 = this.read_unsigned!(workbuf: args.workbuf, part: 0, n: 2) |
| this.num_other_partitions_m1 = ((1 as base.u32) << (v32 & 3)) - 1 |
| |
| // RFC 6386 Section 9.6. Dequantization Indices. |
| v32 = this.read_unsigned!(workbuf: args.workbuf, part: 0, n: 7) |
| this.quant_yac_qi = v32 & 127 |
| this.quant_ydc_delta = this.read_signed!(workbuf: args.workbuf, part: 0, n: 4) |
| this.quant_y2dc_delta = this.read_signed!(workbuf: args.workbuf, part: 0, n: 4) |
| this.quant_y2ac_delta = this.read_signed!(workbuf: args.workbuf, part: 0, n: 4) |
| this.quant_uvdc_delta = this.read_signed!(workbuf: args.workbuf, part: 0, n: 4) |
| this.quant_uvac_delta = this.read_signed!(workbuf: args.workbuf, part: 0, n: 4) |
| this.calculate_dequants!() |
| |
| // RFC 6386 Section 9.7. Refresh Golden Frame and Altref Frame. |
| if not this.is_key_frame { |
| return "#unsupported VP8 file" |
| } |
| |
| // RFC 6386 Section 9.8. Refresh Last Frame Buffer. |
| this.read_bit!(workbuf: args.workbuf, part: 0, prob: 128) |
| |
| // RFC 6386 Section 9.9. DCT Coefficient Probability Update. |
| this.decode_coeff_probs!(workbuf: args.workbuf) |
| |
| if not this.is_key_frame { |
| // RFC 6386 Section 9.10. Remaining Frame Header Data (Non-Key Frame). |
| return "#unsupported VP8 file" |
| |
| } else { |
| // RFC 6386 Section 9.11. Remaining Frame Header Data (Key Frame). |
| v1 = this.read_bit!(workbuf: args.workbuf, part: 0, prob: 128) |
| if v1 <> 0 { |
| v32 = this.read_unsigned!(workbuf: args.workbuf, part: 0, n: 8) |
| this.prob_skip = (v32 & 0xFF) | 0x100 |
| } |
| } |
| |
| return ok |
| } |
| |
| pri func decoder.decode_segment_header!(workbuf: roslice base.u8) { |
| var v1 : base.u32[..= 1] |
| var v32 : base.u32 |
| var i : base.u32 |
| |
| v1 = this.read_bit!(workbuf: args.workbuf, part: 0, prob: 128) |
| this.seg_enabled = v1 <> 0 |
| if not this.seg_enabled { |
| this.seg_update_map = false |
| return nothing |
| } |
| |
| v1 = this.read_bit!(workbuf: args.workbuf, part: 0, prob: 128) |
| this.seg_update_map = v1 <> 0 |
| |
| v1 = this.read_bit!(workbuf: args.workbuf, part: 0, prob: 128) |
| if v1 <> 0 { |
| v1 = this.read_bit!(workbuf: args.workbuf, part: 0, prob: 128) |
| this.seg_absolute = v1 <> 0 |
| |
| i = 0 |
| while i < 4 { |
| v32 = this.read_signed!(workbuf: args.workbuf, part: 0, n: 7) |
| this.seg_quants[i] = (v32 & 0xFF) as base.u8 |
| i += 1 |
| } |
| |
| i = 0 |
| while i < 4 { |
| v32 = this.read_signed!(workbuf: args.workbuf, part: 0, n: 6) |
| this.seg_strengths[i] = (v32 & 0xFF) as base.u8 |
| i += 1 |
| } |
| } |
| |
| if this.seg_update_map { |
| i = 0 |
| while i < 3 { |
| v1 = this.read_bit!(workbuf: args.workbuf, part: 0, prob: 128) |
| if v1 <> 0 { |
| v32 = this.read_unsigned!(workbuf: args.workbuf, part: 0, n: 8) |
| this.seg_probs[i] = (v32 & 0xFF) as base.u8 |
| } else { |
| this.seg_probs[i] = 0xFF |
| } |
| i += 1 |
| } |
| } |
| } |
| |
| pri func decoder.decode_filter_header!(workbuf: roslice base.u8) { |
| var v1 : base.u32[..= 1] |
| var v32 : base.u32 |
| var i : base.u32 |
| |
| v1 = this.read_bit!(workbuf: args.workbuf, part: 0, prob: 128) |
| this.filt_simple = v1 <> 0 |
| |
| v32 = this.read_unsigned!(workbuf: args.workbuf, part: 0, n: 6) |
| this.filt_level = (v32 & 0x3F) as base.u8 |
| |
| v32 = this.read_unsigned!(workbuf: args.workbuf, part: 0, n: 3) |
| this.filt_sharpness = (v32 & 0x07) as base.u8 |
| |
| v1 = this.read_bit!(workbuf: args.workbuf, part: 0, prob: 128) |
| this.filt_deltas_enabled = v1 <> 0 |
| if not this.filt_deltas_enabled { |
| return nothing |
| } |
| |
| v1 = this.read_bit!(workbuf: args.workbuf, part: 0, prob: 128) |
| if v1 == 0 { |
| return nothing |
| } |
| |
| i = 0 |
| while i < 8 { |
| v32 = this.read_signed!(workbuf: args.workbuf, part: 0, n: 6) |
| this.filt_deltas[i >> 2][i & 3] = (v32 & 0xFF) as base.u8 |
| i += 1 |
| } |
| } |
| |
| pri func decoder.decode_coeff_probs!(workbuf: roslice base.u8) { |
| var v1 : base.u32[..= 1] |
| var v32 : base.u32 |
| var i : base.u32 |
| |
| i = 0 |
| while i < 1056 { |
| v1 = this.read_bit!(workbuf: args.workbuf, part: 0, prob: COEFF_UPDATE_PROBS[i] as base.u32) |
| if v1 <> 0 { |
| v32 = this.read_unsigned!(workbuf: args.workbuf, part: 0, n: 8) |
| this.coeff_probs[i] = (v32 & 0xFF) as base.u8 |
| } else { |
| this.coeff_probs[i] = DEFAULT_COEFF_PROBS[i] |
| } |
| i += 1 |
| } |
| } |
| |
| pri func decoder.calculate_dequants!() { |
| var seg : base.u32 |
| var q : base.u32 |
| |
| seg = 0 |
| while seg < 4 { |
| q = this.quant_yac_qi |
| if not this.seg_enabled { |
| // No-op. |
| } else if this.seg_absolute { |
| q = this.util.sign_extend_convert_u8_u32(a: this.seg_quants[seg]) |
| } else { |
| // The (q as base.u32) is redundant, equivalent to q, but avoids a |
| // -Werror=sign-conversion false positive with gcc 12.2.0. |
| q = (q as base.u32) ~mod+ this.util.sign_extend_convert_u8_u32(a: this.seg_quants[seg]) |
| } |
| |
| this.dequants[seg][0][0] = DEQUANTS[0][this.clip_127(a: q ~mod+ this.quant_ydc_delta)] |
| this.dequants[seg][0][1] = DEQUANTS[1][this.clip_127(a: q)] |
| this.dequants[seg][1][0] = DEQUANTS[0][this.clip_127(a: q ~mod+ this.quant_y2dc_delta)] * 2 |
| this.dequants[seg][1][1] = (DEQUANTS[1][this.clip_127(a: q ~mod+ this.quant_y2ac_delta)] * 155) / 100 |
| if this.dequants[seg][1][1] < 8 { |
| this.dequants[seg][1][1] = 8 |
| } |
| this.dequants[seg][2][0] = DEQUANTS[0][this.clip_127(a: q ~mod+ this.quant_uvdc_delta)] |
| if this.dequants[seg][2][0] > 132 { |
| this.dequants[seg][2][0] = 132 |
| } |
| this.dequants[seg][2][1] = DEQUANTS[1][this.clip_127(a: q ~mod+ this.quant_uvac_delta)] |
| |
| seg += 1 |
| } |
| } |
| |
| pri func decoder.clip_127(a: base.u32) base.u32[..= 127] { |
| if args.a >= 0x8000_0000 { |
| return 0 |
| } else if args.a >= 127 { |
| return 127 |
| } |
| return args.a |
| } |
| |
| pri func decoder.decode_other_partition_lengths!(workbuf: roslice base.u8) base.status { |
| var v32 : base.u32 |
| var remainder : base.u32 |
| var i : base.u32 |
| var o : base.u64 |
| |
| remainder = this.partitioned_data_length ~sat- this.part_lens[0] |
| remainder ~sat-= 3 * this.num_other_partitions_m1 |
| |
| o = this.workbuf_yuv_v_end + (this.part_lens[0] as base.u64) |
| i = 0 |
| while i < this.num_other_partitions_m1 { |
| assert i < 7 via "a < b: a < c; c <= b"(c: this.num_other_partitions_m1) |
| |
| v32 = 0 |
| |
| if o >= args.workbuf.length() { |
| return "#bad header" |
| } |
| assert o < 0xFFFF_FFFF_FFFF_FFFF via "a < b: a < c; c <= b"(c: args.workbuf.length()) |
| v32 |= (args.workbuf[o] as base.u32) << 0 |
| o += 1 |
| |
| if o >= args.workbuf.length() { |
| return "#bad header" |
| } |
| assert o < 0xFFFF_FFFF_FFFF_FFFF via "a < b: a < c; c <= b"(c: args.workbuf.length()) |
| v32 |= (args.workbuf[o] as base.u32) << 8 |
| o += 1 |
| |
| if o >= args.workbuf.length() { |
| return "#bad header" |
| } |
| assert o < 0xFFFF_FFFF_FFFF_FFFF via "a < b: a < c; c <= b"(c: args.workbuf.length()) |
| v32 |= (args.workbuf[o] as base.u32) << 16 |
| o += 1 |
| |
| if remainder < v32 { |
| return "#bad header" |
| } |
| remainder -= v32 |
| |
| this.part_lens[1 + i] = v32 |
| |
| i += 1 |
| } |
| |
| if remainder > 0xFF_FFFF { |
| return "#unsupported VP8 file" |
| } |
| this.part_lens[1 + this.num_other_partitions_m1] = remainder |
| |
| i = 0 |
| while i < (1 + this.num_other_partitions_m1) { |
| assert i < 8 via "a < b: a < c; c <= b"(c: (1 + this.num_other_partitions_m1)) |
| |
| this.part_workbuf_ris[1 + i] = o |
| o ~mod+= this.part_lens[1 + i] as base.u64 |
| if o > args.workbuf.length() { |
| return "#bad header" |
| } |
| |
| i += 1 |
| } |
| |
| return ok |
| } |
