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154 lines
3.2 KiB
154 lines
3.2 KiB
#include <stdint.h>
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#include <stdlib.h>
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#include <panic.h>
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#include <attrs.h>
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typedef int64_t i64;
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typedef uint64_t u64;
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const char* const input[] = {
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#ifdef TEST
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#include "input-test.h"
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#else
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#include "input.h"
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#endif
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};
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#define input_sz (sizeof(input)/sizeof(char*))
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typedef struct {
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i64 x, y;
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} point_t;
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typedef struct {
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enum direction {
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DIR_INVALID =0,
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DIR_NORTH = 'N',
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DIR_SOUTH = 'S',
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DIR_EAST = 'E',
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DIR_WEST = 'W',
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DIR_LEFT = 'L',
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DIR_RIGHT = 'R',
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DIR_FORWARD='F',
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} dir;
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i64 num;
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} command_t;
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typedef struct ship {
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point_t pos;
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enum direction facing;
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} svec_t;
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pure inline static command_t parse_single(const char* from)
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{
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register command_t o;
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o.dir = (enum direction)from[0];
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o.num = (i64)atoll(from+1);
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return o;
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}
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inline static void modsign(struct ship* restrict ship, i64 by)
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{
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i64* restrict mod;
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i64 sign = 1;
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switch(ship->facing)
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{
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case DIR_NORTH: sign = -1; fall;
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case DIR_SOUTH: mod = &ship->pos.y;
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break;
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case DIR_WEST: sign = -1; fall;
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case DIR_EAST: mod = &ship->pos.x;
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break;
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default: panic("Invalid facing direction '%c' (%d)", (char) ship->facing, (int) ship->facing);
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}
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*mod += sign * by;
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}
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noglobal static inline enum direction rotr(enum direction s)
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{
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#define DIRECT(n) return n; case n
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switch(s)
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{
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case DIR_NORTH:
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DIRECT(DIR_EAST):
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DIRECT(DIR_SOUTH):
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DIRECT(DIR_WEST):
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return DIR_NORTH;
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default: panic("Cannot rotate direction '%c', (%d)", (char)s, (int) s);
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}
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}
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noglobal static inline enum direction rotl(enum direction s)
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{
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switch(s)
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{
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case DIR_NORTH:
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DIRECT(DIR_WEST):
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DIRECT(DIR_SOUTH):
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DIRECT(DIR_EAST):
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return DIR_NORTH;
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default: panic("Cannot rotate direction '%c', (%d)", (char)s, (int) s);
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}
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}
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#undef DIRECT
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inline extern u64 absll(i64 n)
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{
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return (u64)(n < 0 ? -n : n);
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}
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noglobal static inline enum direction rotd(enum direction from, i64 deg, enum direction by)
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{
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deg /= 90;
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switch(by)
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{
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case DIR_LEFT: for(i64 i=0;i<deg;i++) from = rotl(from); break;
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case DIR_RIGHT: for(i64 i=0;i<deg;i++) from = rotr(from); break;
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default: panic("Cannot rotate direction '%c' (%d)", (char)by, (int)by);
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}
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return from;
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}
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static void handle_com(struct ship* restrict ship, command_t com)
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{
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switch(com.dir)
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{
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case DIR_EAST: ship->pos.x += com.num; break;
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case DIR_WEST: ship->pos.x -= com.num; break;
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case DIR_NORTH: ship->pos.y -= com.num; break;
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case DIR_SOUTH: ship->pos.y += com.num; break;
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/* XXX: LEFT and RIGHT's num is TURN BY DEGREES, not turn, then move!?!?!??? TODO redo
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case DIR_LEFT: ship->facing = rotl(ship->facing); if(0)
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case DIR_RIGHT: ship->facing = rotr(ship->facing);
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*/
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case DIR_RIGHT:
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case DIR_LEFT: ship->facing = rotd(ship->facing, com.num, com.dir);
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break;
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case DIR_FORWARD: modsign(ship, com.num); break;
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default: panic("Unknown command direction '%c' (%d)", (char)com.dir, (int)com.dir);
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}
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#ifdef DEBUG
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fprintf(stderr, "Current location facing %c: %ld x %ld (MD %lu)\n", (char)ship->facing, ship->pos.x, ship->pos.y, absll(ship->pos.x) + absll(ship->pos.y));
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#endif
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}
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int main()
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{
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struct ship ship = { .facing = DIR_EAST, .pos = {0} };
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//command_t comms[input_sz];
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for(size_t i=0;i<input_sz;i++)
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handle_com(&ship, parse_single(input[i]));
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printf("%lu\n", absll(ship.pos.x) + absll(ship.pos.y));
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return 0;
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}
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