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https://github.com/imjasonh/nescript
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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
39 lines
1.3 KiB
Text
39 lines
1.3 KiB
Text
// sha256/showing_state.ne — renders the final digest.
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//
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// Draws the 64-character hexadecimal digest across 8 rows of 8
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// glyphs at the bottom of the screen (see HASH_BASE_Y /
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// HASH_BASE_X in constants.ne). The digest display alone fills
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// the OAM budget, so this state does not draw the input buffer
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// or the keyboard cursor.
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//
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// Pressing B or SELECT clears the buffer and returns to the
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// Entering state so the user can hash another message.
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state Showing {
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on enter {
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blink_timer = 0
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debounce = 20 // swallow the press that
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// brought us here
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}
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on frame {
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blink_timer += 1
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if blink_timer >= 60 {
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blink_timer = 0
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}
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if debounce > 0 {
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debounce -= 1
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}
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// ── Input ────────────────────────────────────────
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if debounce == 0 {
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if button.b or button.select or button.start {
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input_clear()
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transition Entering
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}
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}
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// ── Render the 256-bit digest ───────────────────
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draw_hash()
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}
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}
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