mirror of
https://github.com/imjasonh/nescript
synced 2026-07-08 00:45:38 +00:00
ba23f8578a
An end-to-end FIPS 180-4 SHA-256 hasher running entirely on the NES.
The player types up to 16 ASCII characters on a 5x8 on-screen
keyboard, presses Enter, and the program computes and displays the
64-character hex digest.
Layout (`examples/sha256/*.ne`):
constants.ne layout + K[64] / H_INIT[8] tables
(declared as `var` with init_array because the
v0.1 compiler treats `const u8[N] = [...]` as
a no-op — noted in the file)
assets.ne 44-tile Tileset (A..Z, 0..9, punctuation,
special keys, cursor) shared between BG and
sprite layers
background.ne static nametable (title, labels, keyboard
grid) painted at reset
state.ne globals
sha_core.ne 32-bit byte primitives (copy, xor, and, add,
not, rotr, shr) in inline asm + sigma/Sigma
mixers + schedule/round steps + fold
render.ne OAM helpers for cursor, input buffer, and
64-nibble digest
keyboard.ne key dispatch table
entering_state.ne cursor navigation + typing + auto-demo
computing_state.ne phased driver (48 schedule steps + 64 rounds
+ fold across ~30 frames at 4 iterations each)
showing_state.ne renders the 256-bit digest as 8 rows of 8
sprite glyphs
Implementation notes:
- All 32-bit words live as 4 little-endian bytes in `wk[64]`,
`w[256]`, `h_state[32]` so every primitive walks four bytes with
`LDA {arr},X`/`STA {arr},X` chains and, for adds, a carry chain.
- Every primitive reads its parameters straight out of the
transport slots `$04`/`$05` rather than `{dst}`/`{src}`
substitutions: the inline-asm resolver looks parameters up in
the analyzer's allocation table but the codegen spills them to a
different per-function RAM slot, so `{dst}` would resolve to a
ZP slot nothing ever writes to. Bypassing the substitution
entirely sidesteps the issue without a compiler change.
- Rotate-right by any amount is a byte-rotate loop plus a bit-
rotate loop so the 10 SHA amounts (2, 6, 7, 11, 13, 17, 18, 19,
22, 25) all compile to a handful of chained `ROR`s.
- The headless jsnes golden auto-types "NES" after 1 s of idle and
captures its SHA-256 digest
AE9145DB5CABC41FE34B54E34AF8881F462362EA20FD8F861B26532FFBB84E0D
— byte-identical to `shasum` / `hashlib.sha256(b"NES")`.
Build: `cargo run --release -- build examples/sha256.ne`
https://claude.ai/code/session_01FRmSBruVWCufm3LsUVMs8v
52 lines
2.5 KiB
Text
52 lines
2.5 KiB
Text
// sha256/state.ne — global variables.
|
|
//
|
|
// Every piece of cross-handler state lives here so Entering,
|
|
// Computing, and Showing can share buffers (and, crucially, so
|
|
// the message buffer survives the state transition from
|
|
// Entering → Computing without being reinitialised).
|
|
|
|
// ── Cursor position on the keyboard ─────────────────────────
|
|
var kb_row: u8 = 0 // 0..KB_ROWS-1
|
|
var kb_col: u8 = 0 // 0..KB_COLS-1
|
|
|
|
// ── Input buffer + length ───────────────────────────────────
|
|
var msg: u8[16] // INPUT_MAX ASCII bytes
|
|
var msg_len: u8 = 0 // 0..INPUT_MAX
|
|
|
|
// ── SHA-256 working memory ──────────────────────────────────
|
|
//
|
|
// `h_state` holds the running hash (8 u32 words, little-endian);
|
|
// it's initialised from H_INIT on every new compression so users
|
|
// can run more than one hash per power-on. `w` is the 64-entry
|
|
// message schedule (256 bytes). `wk` is the scratch area that
|
|
// hosts the a..h registers plus T1/T2/Σ/tmp — see
|
|
// constants.ne for the byte offsets.
|
|
var h_state: u8[32]
|
|
var w: u8[256]
|
|
var wk: u8[64]
|
|
|
|
// ── Compression driver state ────────────────────────────────
|
|
//
|
|
// The compression is split across frames so the main loop never
|
|
// overruns vblank. `cp_phase` selects which block of work runs
|
|
// this frame; see computing_state.ne for the phase table.
|
|
var cp_phase: u8 = 0
|
|
|
|
// ── Input-idle timer ────────────────────────────────────────
|
|
//
|
|
// Incremented every frame while Entering sees no button presses.
|
|
// When it reaches AUTO_DELAY the state auto-types DEMO_TEXT and
|
|
// transitions to Computing, so the headless jsnes golden always
|
|
// captures a populated hash screen.
|
|
var idle_timer: u8 = 0
|
|
|
|
// Debounces repeat-fire for the face and special keys so one
|
|
// press is registered as one key press rather than one per frame
|
|
// held.
|
|
var debounce: u8 = 0
|
|
|
|
// ── Cursor blink ────────────────────────────────────────────
|
|
//
|
|
// The cursor sprite on the keyboard pulses at ~2 Hz. Also used
|
|
// by Showing to mark "PRESS B TO RESET".
|
|
var blink_timer: u8 = 0
|