86 lines
1.6 KiB
C
86 lines
1.6 KiB
C
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#include <stdio.h>
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int prog[] = {2,4,1,1,7,5,4,4,1,4,0,3,5,5,3,0};
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int plen = sizeof(prog) / sizeof(int);
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int run(long a, int i, int print) {
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long b = 0;
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long c = 0;
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int ip;
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for (ip = 0; ip+2 <= plen; ip += 2) {
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int op = prog[ip];
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long r = prog[ip+1];
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if (op != 1 && op != 3 && op != 4 && r > 3) {
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// combo op
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if (r == 4) {
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r = a;
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} else if (r == 5) {
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r = b;
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} else if (r == 6) {
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r = c;
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} else if (r >= 7) {
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return -1; // invalid
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}
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}
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switch(op) {
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case 0: a = a >> r; break; // adv
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case 6: b = a >> r; break; // bdv
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case 7: c = a >> r; break; // cdv
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case 1: b ^= r; break; // bxl
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case 2: b = r % 8; break; // bst
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case 4: b ^= c; break; // bxc
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case 3: if (a != 0) ip = r-2; break; // jnz
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case 5: // out
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int o = r % 8;
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if (print) {
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printf("%d ", o);
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} else {
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if (o != prog[i++]) {
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return -2;
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}
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}
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break;
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default:
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return -1; //invalid
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}
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}
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if (print) printf("\b\n");
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return 0;
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}
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// assumptions:
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// - the whole program is a loop
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// - 'a' is decoded 3 bits at a time
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// - output only affected by higher bits, not lower bits
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long reverse(long init, int i) {
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if (i < 0) {
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return init;
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}
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for (int b = 0; b < 8; b++) {
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long a = init<<3 | b;
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if (run(a, i, 0) == 0) {
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printf("# %lo\n", a);
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long ret = reverse(a, i-1);
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if (ret >= 0) {
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return ret;
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}
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}
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}
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//error
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return -3;
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}
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int main() {
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run(46337277, 0, 1);
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run(202991746427434L, 0, 1);
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long a = reverse(0, plen-1);
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printf("%ld\n", a);
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if (a >= 0) {
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printf("%d\n", run(a, 0, 1));
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}
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return 0;
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}
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