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Diffstat (limited to '')
| -rw-r--r-- | bin/beef.c | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/bin/beef.c b/bin/beef.c new file mode 100644 index 00000000..556742d9 --- /dev/null +++ b/bin/beef.c @@ -0,0 +1,139 @@ +/* Copyright (C) 2019 C. McEnroe <june@causal.agency> + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU Affero General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU Affero General Public License for more details. + * + * You should have received a copy of the GNU Affero General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <err.h> +#include <stdbool.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sysexits.h> + +enum { + Cols = 80, + Rows = 25, +}; +static char page[Rows][Cols]; + +static char get(int y, int x) { + if (y < 0 || y >= Rows) return 0; + if (x < 0 || x >= Cols) return 0; + return page[y][x]; +} +static void put(int y, int x, char v) { + if (y < 0 || y >= Rows) return; + if (x < 0 || x >= Cols) return; + page[y][x] = v; +} + +enum { StackLen = 1024 }; +static long stack[StackLen]; +static size_t top = StackLen; + +static void push(long val) { + if (!top) errx(EX_SOFTWARE, "stack overflow"); + stack[--top] = val; +} +static long pop(void) { + if (top == StackLen) return 0; + return stack[top++]; +} + +static struct { + int y, x; + int dy, dx; +} pc = { .dx = 1 }; + +static void inc(void) { + pc.y += pc.dy; + pc.x += pc.dx; + if (pc.y == -1) pc.y += Rows; + if (pc.x == -1) pc.x += Cols; + if (pc.y == Rows) pc.y -= Rows; + if (pc.x == Cols) pc.x -= Cols; +} + +static bool string; + +static bool step(void) { + char ch = page[pc.y][pc.x]; + + if (ch == '"') { + string ^= true; + } else if (string) { + push(ch); + inc(); + return true; + } + + if (ch == '?') ch = "><^v"[arc4random_uniform(4)]; + + long x, y, v; + switch (ch) { + break; case '+': push(pop() + pop()); + break; case '-': y = pop(); x = pop(); push(x - y); + break; case '*': push(pop() * pop()); + break; case '/': y = pop(); x = pop(); push(x / y); + break; case '%': y = pop(); x = pop(); push(x % y); + break; case '!': push(!pop()); + break; case '`': y = pop(); x = pop(); push(x > y); + break; case '>': pc.dy = 0; pc.dx = +1; + break; case '<': pc.dy = 0; pc.dx = -1; + break; case '^': pc.dy = -1; pc.dx = 0; + break; case 'v': pc.dy = +1; pc.dx = 0; + break; case '_': pc.dy = 0; pc.dx = (pop() ? -1 : +1); + break; case '|': pc.dx = 0; pc.dy = (pop() ? -1 : +1); + break; case ':': x = pop(); push(x); push(x); + break; case '\\': y = pop(); x = pop(); push(y); push(x); + break; case '$': pop(); + break; case '.': printf("%ld ", pop()); fflush(stdout); + break; case ',': printf("%c", (char)pop()); fflush(stdout); + break; case '#': inc(); + break; case 'g': y = pop(); x = pop(); push(get(y, x)); + break; case 'p': y = pop(); x = pop(); v = pop(); put(y, x, v); + break; case '&': x = EOF; scanf("%ld", &x); push(x); + break; case '~': push(getchar()); + break; case '@': return false; + break; default: if (ch >= '0' && ch <= '9') push(ch - '0'); + } + + inc(); + return true; +} + +int main(int argc, char *argv[]) { + memset(page, ' ', sizeof(page)); + + FILE *file = stdin; + if (argc > 1) { + file = fopen(argv[1], "r"); + if (!file) err(EX_NOINPUT, "%s", argv[1]); + } + + int y = 0; + char *line = NULL; + size_t cap = 0; + while (y < Rows && 0 < getline(&line, &cap, file)) { + for (int x = 0; x < Cols; ++x) { + if (line[x] == '\n' || !line[x]) break; + page[y][x] = line[x]; + } + y++; + } + free(line); + + while (step()); + return pop(); +} |