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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
62 lines
1.9 KiB
Text
62 lines
1.9 KiB
Text
// sha256/keyboard.ne — key-to-character lookup + input dispatch.
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//
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// The on-screen keyboard is a 5-row × 8-column grid of cells.
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// `kb_row` and `kb_col` in state.ne store the cursor position.
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// The character produced when the user presses A is looked up
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// here. Special values are encoded with ASCII control codes so
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// they're distinguishable from printable bytes:
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//
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// KEY_BKSP (0x08) — bottom row col 6. Delete one char.
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// KEY_ENTER (0x0A) — bottom row col 7. Start compression.
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//
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// The grid layout (matches the keyboard in background.ne):
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//
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// row 0: A B C D E F G H
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// row 1: I J K L M N O P
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// row 2: Q R S T U V W X
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// row 3: Y Z 0 1 2 3 4 5
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// row 4: 6 7 8 9 _ . < >
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var KB_CHARS: u8[40] = [
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0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, // A B C D E F G H
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0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F, 0x50, // I J K L M N O P
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0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, // Q R S T U V W X
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0x59, 0x5A, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, // Y Z 0 1 2 3 4 5
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0x36, 0x37, 0x38, 0x39, 0x20, 0x2E, 0x08, 0x0A // 6 7 8 9 ' ' '.' BKSP ENTER
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]
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// Look up the character emitted by the key at (kb_row, kb_col).
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fun current_key() -> u8 {
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var idx: u8 = (kb_row << 3) + kb_col // row * 8 + col
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return KB_CHARS[idx]
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}
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// Append a byte to the input buffer. Does nothing if the buffer
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// is already at INPUT_MAX — users wanting to correct their
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// input reach for backspace first.
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fun input_append(ch: u8) {
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if msg_len >= INPUT_MAX {
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return
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}
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msg[msg_len] = ch
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msg_len += 1
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}
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// Delete the last byte, if any.
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fun input_backspace() {
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if msg_len == 0 {
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return
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}
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msg_len -= 1
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msg[msg_len] = 0
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}
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// Wipe the entire buffer. Triggered by SELECT from any state.
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fun input_clear() {
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var i: u8 = 0
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while i < INPUT_MAX {
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msg[i] = 0
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i += 1
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}
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msg_len = 0
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}
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