nx_jpeg_decode.nx

nx_jpeg_decode.nx -- top-level baseline-JPEG decoder. The marker-walking front-end that ties every brick in the JPEG arc into a bytes-in / sample-planes-out API. Pipeline: jpeg_bytes -> nx_jpeg_seg_next (marker scan) for each segment: DQT -> nx_jpeg_dqt_parse, append to qtables DHT -> nx_jpeg_dht_parse, append to htables SOF0 -> nx_jpeg_sof_parse, store frame SOS -> nx_jpeg_sos_parse, store scan + record entropy_off (entropy bytes run from segment end to EOI) else -> skip (APP / COM / etc.) -> nx_jpeg_decode_image_resolve (per-component table lookup) -> nx_jpeg_decode_image_walk_mcus (MCU grid driver) Output: per-component sample planes filled. Caller upsamples + YCbCr->RGB to produce the final RGB framebuffer. Caller supplies all the storage (frame + scan + qtables + htables + per-component planes). Substrate adds no malloc beyond the scratch arenas internal to per-block primitives. nx_safety_envelope: intended_use: "Top-level baseline-JPEG decode -- bytes-in, sample-planes-out. Last brick before YCbCr->RGB upsample step." sil_target: SIL1 evidence: [composes_marker_dqt_dht_sof_sos_decode_image, sealed_verdicts_per_segment_kind, bounded_iteration] hazard_register: [bug-tape-progressive-mistaken-baseline, bug-tape-restart-marker-not-honored, bug-tape-app-segment-length-overrun] residual_risk: "Baseline (SOF0) only. Progressive (SOF2), extended-sequential (SOF1), and arithmetic- coded variants reject with NOT_BASELINE." verdict: NOT_YET_EVALUATED