code wiki / (root) / nx_legacy_codec_gate.nx
`nx_legacy_codec_gate.nx` source

↩ module page · 289 lines · 11681 B
1// nx_legacy_codec_gate.nx -- gate for the 1990s reader set: TGA, PCX, ICO/CUR
2// and PNM, plus their chokepoint wiring.
3//
4// NO THIRD-PARTY FILE OF ANY OF THESE FORMATS EXISTS ANYWHERE UNDER knowledge/
5// (measured: a full extension census returned zero, and a magic scan over
6// 40,000 files found only our own containers). So the witness is a MATURE
7// INDEPENDENT ENCODER -- PIL/libtga/libpcx wrote every fixture in
8// knowledge/fixtures/legacy_codec, and the expected pixels below are that
9// encoder's OWN read-back, not our assumption about what it wrote. Same
10// standing as the BMP writer/reader round-trip: two independent
11// implementations agreeing byte-exactly.
12//
13// The probe image is 7x5 -- odd, and not a multiple of 8 -- so every stride
14// pad, plane split and row-order bug has somewhere to show. Its pixels vary
15// in BOTH axes, so a vertical flip, a horizontal flip and a transpose are all
16// separately detectable; a symmetric fixture would pass while mirrored.
17//
18// license_tier: ORIGINAL  expect_exit: 0
19import "nx_syscalls.nx"
20import "nx_gate_verdict.nx"
21import "nx_tga_decode.nx"
22import "nx_pcx_decode.nx"
23import "nx_ico_decode.nx"
24import "nx_pnm_decode.nx"
25import "nx_img_bytes_to_rgb.nx"
26
27const LG_DIR: i64 = 0
28
29// check one pixel of a decoded RGB buffer
30func lg_px(rgb: *u8, w: i64, x: i64, y: i64, r: i64, g: i64, b: i64) -> i64 {
  let o: i64 = (y*w + x) * 3
  if ((rgb[o] as i64) & 255) != r { return 0 }
  if ((rgb[o+1] as i64) & 255) != g { return 0 }
  if ((rgb[o+2] as i64) & 255) != b { return 0 }
  return 1
36}
37
38// read a fixture; returns bytes in box[0], pointer as the result
39func lg_read(name: *u8, box: *i64) -> *u8 {
  return sys_read_file(name, box)
41}
42
43func main() -> i64 {
  let ctr: *i64 = gv_ctr()
  gv_head("nx_legacy_codec_gate -- 1990s roster: TGA/PCX/ICO/PNM + chokepoint" as *u8)
46
  let box: *i64 = sys_mmap(16) as *i64
  let wh: *i64 = sys_mmap(32) as *i64
49
  // ---------- T1 TGA uncompressed 24-bit ----------
  var t1: i64 = 0
  let f1: *u8 = lg_read("knowledge/fixtures/legacy_codec/t_plain.tga" as *u8, box)
  let n1: i64 = box[0]
  var rgb1: *u8 = 0 as *u8
  if f1 != (0 as *u8) {
      wh[0]=0
      wh[1]=0
      rgb1 = tga_decode_rgb(f1, n1, wh)
      if rgb1 != (0 as *u8) { if wh[0]==7 { if wh[1]==5 {
          var ok: i64 = 1
          if lg_px(rgb1,7,0,0,5,90,3)==0 { ok=0 }
          if lg_px(rgb1,7,6,0,227,90,69)==0 { ok=0 }
          if lg_px(rgb1,7,0,4,5,46,31)==0 { ok=0 }
          if lg_px(rgb1,7,6,4,227,46,97)==0 { ok=0 }
          if lg_px(rgb1,7,3,2,116,196,178)==0 { ok=0 }
          if lg_px(rgb1,7,1,2,42,196,156)==0 { ok=0 }
          t1 = ok
      } } }
  }
  gv_check("T1 TGA 24-bit uncompressed: 6 pixels exact vs independent encoder" as *u8, t1, ctr)
71
  // ---------- T2 TGA RLE == uncompressed (wire-different files) ----------
  var t2: i64 = 0
  let f2: *u8 = lg_read("knowledge/fixtures/legacy_codec/t_rle.tga" as *u8, box)
  let n2: i64 = box[0]
  if f2 != (0 as *u8) { if rgb1 != (0 as *u8) {
      wh[0]=0
      wh[1]=0
      let rgb2: *u8 = tga_decode_rgb(f2, n2, wh)
      if rgb2 != (0 as *u8) { if wh[0]==7 { if wh[1]==5 {
          // vacuity guard: the two files MUST differ on the wire, else this
          // check proves nothing about the RLE path at all
          var differ: i64 = 0
          if n1 != n2 { differ = 1 }
          var same: i64 = 1
          var i: i64 = 0
          while i < 7*5*3 { if rgb1[i] != rgb2[i] { same = 0; i = 7*5*3 } else { i = i + 1 } }
          if differ == 1 { if same == 1 { t2 = 1 } }
      } } }
  } }
  gv_check("T2 TGA RLE decodes identical to uncompressed (wire-different)" as *u8, t2, ctr)
92
  // ---------- T3 TGA 8-bit grayscale ----------
  var t3: i64 = 0
  let f3: *u8 = lg_read("knowledge/fixtures/legacy_codec/t_gray.tga" as *u8, box)
  if f3 != (0 as *u8) {
      wh[0]=0
      wh[1]=0
      let r3: *u8 = tga_decode_rgb(f3, box[0], wh)
      if r3 != (0 as *u8) { if wh[0]==7 { if wh[1]==5 {
          var ok: i64 = 1
          if lg_px(r3,7,0,0,55,55,55)==0 { ok=0 }
          if lg_px(r3,7,6,0,129,129,129)==0 { ok=0 }
          if lg_px(r3,7,0,4,32,32,32)==0 { ok=0 }
          if lg_px(r3,7,6,4,106,106,106)==0 { ok=0 }
          if lg_px(r3,7,3,2,170,170,170)==0 { ok=0 }
          t3 = ok
      } } }
  }
  gv_check("T3 TGA 8-bit grayscale: 5 pixels exact" as *u8, t3, ctr)
111
  // ---------- T4 PCX 24-bit planar ----------
  var t4: i64 = 0
  let f4: *u8 = lg_read("knowledge/fixtures/legacy_codec/p_rgb.pcx" as *u8, box)
  if f4 != (0 as *u8) {
      wh[0]=0
      wh[1]=0
      let r4: *u8 = pcx_decode_rgb(f4, box[0], wh)
      if r4 != (0 as *u8) { if wh[0]==7 { if wh[1]==5 {
          var ok: i64 = 1
          if lg_px(r4,7,0,0,5,90,3)==0 { ok=0 }
          if lg_px(r4,7,6,0,227,90,69)==0 { ok=0 }
          if lg_px(r4,7,0,4,5,46,31)==0 { ok=0 }
          if lg_px(r4,7,6,4,227,46,97)==0 { ok=0 }
          if lg_px(r4,7,1,2,42,196,156)==0 { ok=0 }
          t4 = ok
      } } }
  }
  gv_check("T4 PCX 24-bit planar (plane split, not RGB triples)" as *u8, t4, ctr)
130
  // ---------- T5 PCX 8-bit palette (trailing 769-byte palette) ----------
  var t5: i64 = 0
  let f5: *u8 = lg_read("knowledge/fixtures/legacy_codec/p_pal.pcx" as *u8, box)
  if f5 != (0 as *u8) {
      wh[0]=0
      wh[1]=0
      let r5: *u8 = pcx_decode_rgb(f5, box[0], wh)
      if r5 != (0 as *u8) { if wh[0]==7 { if wh[1]==5 {
          var ok: i64 = 1
          if lg_px(r5,7,0,0,5,90,3)==0 { ok=0 }
          if lg_px(r5,7,6,0,227,90,69)==0 { ok=0 }
          if lg_px(r5,7,0,4,5,46,31)==0 { ok=0 }
          if lg_px(r5,7,6,4,227,46,97)==0 { ok=0 }
          t5 = ok
      } } }
  }
  gv_check("T5 PCX 8-bit palette via trailing 0x0C palette block" as *u8, t5, ctr)
148
  // ---------- T6 ICO: LARGEST frame chosen from a 16+32 multi-size file ----------
  var t6: i64 = 0
  let f6: *u8 = lg_read("knowledge/fixtures/legacy_codec/i_multi.ico" as *u8, box)
  if f6 != (0 as *u8) {
      wh[0]=0
      wh[1]=0
      let r6: *u8 = ico_decode_rgb(f6, box[0], wh)
      if r6 != (0 as *u8) { if wh[0]==32 { if wh[1]==32 {
          var ok: i64 = 1
          if lg_px(r6,32,0,0,5,90,3)==0 { ok=0 }
          if lg_px(r6,32,31,0,227,90,69)==0 { ok=0 }
          if lg_px(r6,32,0,31,5,46,31)==0 { ok=0 }
          if lg_px(r6,32,31,31,227,46,97)==0 { ok=0 }
          if lg_px(r6,32,16,16,116,196,178)==0 { ok=0 }
          t6 = ok
      } } }
  }
  gv_check("T6 ICO picks the 32x32 frame over the 16x16 and decodes it" as *u8, t6, ctr)
167
  // ---------- T7 PNM P6 binary colour ----------
  var t7: i64 = 0
  let f7: *u8 = lg_read("knowledge/fixtures/legacy_codec/n_p6.ppm" as *u8, box)
  if f7 != (0 as *u8) {
      wh[0]=0
      wh[1]=0
      let r7: *u8 = pnm_decode_rgb(f7, box[0], wh)
      if r7 != (0 as *u8) { if wh[0]==7 { if wh[1]==5 {
          var ok: i64 = 1
          if lg_px(r7,7,0,0,5,90,3)==0 { ok=0 }
          if lg_px(r7,7,6,0,227,90,69)==0 { ok=0 }
          if lg_px(r7,7,6,4,227,46,97)==0 { ok=0 }
          if lg_px(r7,7,1,2,42,196,156)==0 { ok=0 }
          t7 = ok
      } } }
  }
  gv_check("T7 PNM P6 binary colour (single-whitespace payload start)" as *u8, t7, ctr)
185
  // ---------- T8 PNM P5 gray + P4 bitmap (1 = BLACK) ----------
  var t8a: i64 = 0
  let f8: *u8 = lg_read("knowledge/fixtures/legacy_codec/n_p5.pgm" as *u8, box)
  if f8 != (0 as *u8) {
      wh[0]=0
      wh[1]=0
      let r8: *u8 = pnm_decode_rgb(f8, box[0], wh)
      if r8 != (0 as *u8) { if wh[0]==7 {
          var ok: i64 = 1
          if lg_px(r8,7,0,0,55,55,55)==0 { ok=0 }
          if lg_px(r8,7,6,0,129,129,129)==0 { ok=0 }
          if lg_px(r8,7,3,2,170,170,170)==0 { ok=0 }
          t8a = ok
      } }
  }
  var t8b: i64 = 0
  let f9: *u8 = lg_read("knowledge/fixtures/legacy_codec/n_p4.pbm" as *u8, box)
  if f9 != (0 as *u8) {
      wh[0]=0
      wh[1]=0
      let r9: *u8 = pnm_decode_rgb(f9, box[0], wh)
      if r9 != (0 as *u8) { if wh[0]==7 { if wh[1]==5 {
          var ok: i64 = 1
          if lg_px(r9,7,0,0,0,0,0)==0 { ok=0 }
          if lg_px(r9,7,6,4,255,255,255)==0 { ok=0 }
          if lg_px(r9,7,3,2,255,255,255)==0 { ok=0 }
          if lg_px(r9,7,1,2,0,0,0)==0 { ok=0 }
          t8b = ok
      } } }
  }
  var t8: i64 = 0
  if t8a == 1 { if t8b == 1 { t8 = 1 } }
  gv_check("T8 PNM P5 gray and P4 bitmap (1 means black)" as *u8, t8, ctr)
219
  // ---------- T9 BITE: truncated PCX refused, intact decodes ----------
  var b9bad: i64 = 0
  var b9good: i64 = 1
  if f4 != (0 as *u8) {
      wh[0]=0
      wh[1]=0
      if pcx_decode_rgb(f4, 140, wh) == (0 as *u8) { b9bad = 1 }
      wh[0]=0
      wh[1]=0
      let g: *u8 = lg_read("knowledge/fixtures/legacy_codec/p_rgb.pcx" as *u8, box)
      if pcx_decode_rgb(g, box[0], wh) != (0 as *u8) { b9good = 0 }
  }
  gv_bite("T9 truncated-PCX refusal" as *u8, b9bad, b9good, ctr)
233
  // ---------- T10 BITE: TGA with an unknown image type refused ----------
  var b10bad: i64 = 0
  var b10good: i64 = 1
  if f1 != (0 as *u8) {
      let cp: *u8 = sys_mmap(n1 + 64)
      var i: i64 = 0
      while i < n1 { cp[i] = f1[i]; i = i + 1 }
      cp[2] = 32 as u8            // type 32 = Huffman+delta, deliberately unsupported
      wh[0]=0
      wh[1]=0
      if tga_decode_rgb(cp, n1, wh) == (0 as *u8) { b10bad = 1 }
      wh[0]=0
      wh[1]=0
      if tga_decode_rgb(f1, n1, wh) != (0 as *u8) { b10good = 0 }
  }
  gv_bite("T10 unsupported-TGA-type refusal (never a wrong image)" as *u8, b10bad, b10good, ctr)
250
  // ---------- T11 chokepoint inherits all four, BY MAGIC not extension ----------
  var t11: i64 = 0
  if f1 != (0 as *u8) {
      var c: i64 = 0
      wh[0]=0
      wh[1]=0
      if nx_img_bytes_to_rgb(f1, n1, wh) != (0 as *u8) { if wh[0]==7 { if wh[1]==5 { c = c + 1 } } }
      let g4: *u8 = lg_read("knowledge/fixtures/legacy_codec/p_rgb.pcx" as *u8, box)
      wh[0]=0
      wh[1]=0
      if nx_img_bytes_to_rgb(g4, box[0], wh) != (0 as *u8) { if wh[0]==7 { c = c + 1 } }
      let g6: *u8 = lg_read("knowledge/fixtures/legacy_codec/i_multi.ico" as *u8, box)
      wh[0]=0
      wh[1]=0
      if nx_img_bytes_to_rgb(g6, box[0], wh) != (0 as *u8) { if wh[0]==32 { c = c + 1 } }
      let g7: *u8 = lg_read("knowledge/fixtures/legacy_codec/n_p6.ppm" as *u8, box)
      wh[0]=0
      wh[1]=0
      if nx_img_bytes_to_rgb(g7, box[0], wh) != (0 as *u8) { if wh[0]==7 { c = c + 1 } }
      if c == 4 { t11 = 1 }
  }
  gv_check("T11 chokepoint decodes TGA+PCX+ICO+PNM by magic sniff" as *u8, t11, ctr)
273
  // ---------- T12 no REGRESSION: PNG still reaches the PNG fallback ----------
  // The TGA sniff is magicless and runs LAST; this proves it did not swallow
  // a format that must fall through to a later branch.
  var t12: i64 = 0
  let fp: *u8 = lg_read("knowledge/media/julia_kyoka/1e3abfbdd077fad1bbcbb2158887f76a1e913fa3fafb722ad28ccadba7fc796b.png" as *u8, box)
  if fp != (0 as *u8) {
      wh[0]=0
      wh[1]=0
      if nx_img_bytes_to_rgb(fp, box[0], wh) != (0 as *u8) { if wh[0]>0 { if wh[1]>0 { t12 = 1 } } }
  }
  gv_check("T12 PNG still decodes (magicless TGA sniff swallowed nothing)" as *u8, t12, ctr)
285
  let rc: i64 = gv_verdict("LEGACY-CODEC-GATE" as *u8, ctr, "1990s roster: TGA/PCX/ICO/PNM, independent-encoder witnesses" as *u8)
  sys_exit(rc)
  return rc
289}
nx_legacy_codec_gate.nx source

`nx_legacy_codec_gate.nx` source
