1
0
Fork 0
mirror of https://github.com/imjasonh/nescript synced 2026-07-11 18:20:47 +00:00
nescript/examples/sha256/showing_state.ne

40 lines
1.3 KiB
Text
Raw Normal View History

examples/sha256: interactive SHA-256 hasher with on-screen keyboard 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
2026-04-16 14:02:58 +00:00
// sha256/showing_state.ne — renders the final digest.
//
// Draws the 64-character hexadecimal digest across 8 rows of 8
// glyphs at the bottom of the screen (see HASH_BASE_Y /
// HASH_BASE_X in constants.ne). The digest display alone fills
// the OAM budget, so this state does not draw the input buffer
// or the keyboard cursor.
//
// Pressing B or SELECT clears the buffer and returns to the
// Entering state so the user can hash another message.
state Showing {
on enter {
blink_timer = 0
debounce = 20 // swallow the press that
// brought us here
}
on frame {
blink_timer += 1
if blink_timer >= 60 {
blink_timer = 0
}
if debounce > 0 {
debounce -= 1
}
// ── Input ────────────────────────────────────────
if debounce == 0 {
if button.b or button.select or button.start {
input_clear()
transition Entering
}
}
// ── Render the 256-bit digest ───────────────────
draw_hash()
}
}