diff options
| -rw-r--r-- | .gitignore | 1 | ||||
| -rw-r--r-- | usth/ICT3.4/a51.c | 54 | ||||
| -rw-r--r-- | usth/ICT3.4/powmod.scm | 9 | ||||
| -rw-r--r-- | usth/ICT3.4/pset.pdf | bin | 0 -> 70440 bytes | |||
| -rw-r--r-- | usth/ICT3.4/rsa.lsp | 20 |
5 files changed, 84 insertions, 0 deletions
diff --git a/.gitignore b/.gitignore index 3d894d7..1338573 100644 --- a/.gitignore +++ b/.gitignore @@ -1,2 +1,3 @@ *~ *.fasl +a.out diff --git a/usth/ICT3.4/a51.c b/usth/ICT3.4/a51.c new file mode 100644 index 0000000..7925f02 --- /dev/null +++ b/usth/ICT3.4/a51.c @@ -0,0 +1,54 @@ +#include <stdio.h> + +#define READ(t, n) for (int i = 0; i < n; ++i) t = t << 1 | (getchar() ^ 48) +#define POW2(t) (1 << (t)) + +#define MAXX POW2(18) +#define MAXY POW2(21) +#define MAXZ POW2(22) + +#define CLOCKX(x) ((x) & POW2(10)) +#define CLOCKY(y) ((y) & POW2(11)) +#define CLOCKZ(z) ((z) & POW2(12)) + +#define BIT(n, t) (((t) & POW2(n)) != 0) + +#define TAPX(x) ((BIT(0, x) ^ BIT(1, x) ^ BIT(2, x) ^ BIT(5, x)) << 18) +#define TAPY(y) ((BIT(0, y) ^ BIT(1, y)) << 21) +#define TAPZ(z) ((BIT(0, z) ^ BIT(1, z) ^ BIT(2, z) ^ BIT(15, z)) << 22) + +int main() +{ + int x = 0, y = 0, z = 0; + READ(x, 19); + getchar(); /* assume one-char sep */ + READ(y, 22); + getchar(); /* assume one-char sep */ + READ(z, 23); + + int n; + scanf("%d", &n); + while (n--) { + int minor = !CLOCKX(x) + !CLOCKY(y) + !CLOCKZ(z) > 1; + putchar(((x ^ y ^ z) & 1) + '0'); + + if (minor == !CLOCKX(x)) { + x >>= 1; + x &= ~MAXX; + x |= TAPX(x); + } + if (minor == !CLOCKY(y)) { + y >>= 1; + y &= ~MAXY; + y |= TAPY(y); + } + if (minor == !CLOCKZ(z)) { + z >>= 1; + z &= z & ~MAXZ; + z |= TAPZ(z); + } + } + + putchar(10); + return 0; +} diff --git a/usth/ICT3.4/powmod.scm b/usth/ICT3.4/powmod.scm new file mode 100644 index 0000000..b21e995 --- /dev/null +++ b/usth/ICT3.4/powmod.scm @@ -0,0 +1,9 @@ +(define (square x) (* x x)) +(display + (let powmod ((x (read)) (e (read)) (m (read))) + ; let's ignore negative e here + (cond ((= e 0) 1) + ((= e 1) (remainder x m)) + ((even? e) (remainder (square (powmod x (/ e 2) m)) m)) + (else (remainder (* (square (powmod x (quotient e 2) m)) x) m))))) +(newline) diff --git a/usth/ICT3.4/pset.pdf b/usth/ICT3.4/pset.pdf new file mode 100644 index 0000000..e7af75f --- /dev/null +++ b/usth/ICT3.4/pset.pdf Binary files differdiff --git a/usth/ICT3.4/rsa.lsp b/usth/ICT3.4/rsa.lsp new file mode 100644 index 0000000..0461ea3 --- /dev/null +++ b/usth/ICT3.4/rsa.lsp @@ -0,0 +1,20 @@ +(defun square (x) (* x x)) + +(defun modexpt (x e m) + (cond ((= e 0) 1) + ((= e 1) (mod x m)) + ((evenp e) (mod (square (modexpt x (/ e 2) m)) m)) + (t (mod (* (square (modexpt x (floor e 2) m)) x) m)))) + +(defun modinv (x m &optional (b m) (a 0) (u 1)) + (if (= x 0) + (when (= b 1) (mod a m)) + (modinv (mod b x) m x u (- a (* u (floor b x)))))) + +(defun rsa (p q &optional e d m c) + (let ((n (* p q)) + (l (* (1- p) (1- q)))) + (cond ((not e) (rsa p q (modinv d l) d m c)) + ((not d) (rsa p q e (modinv e l) m c)) + ((not m) (modexpt c d n)) + ((not c) (modexpt m e n))))) |