Add dice

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 195 insertions, 0 deletions

diff --git a/dice.c b/dice.c
new file mode 100644
index 0000000..69fc911
--- /dev/null
+++ b/dice.c
@@ -0,0 +1,195 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+#include <sys/random.h>
+
+/* TODO add support for up and down arrows to browse previous entries in the same session */
+
+USAGE("");
+
+
+struct die {
+	intmax_t count;
+	intmax_t min;
+	intmax_t max;
+};
+
+
+static intmax_t
+random_int(intmax_t min, intmax_t max)
+{
+	uintmax_t res, max0 = (uintmax_t)max - (uintmax_t)min, max1;
+	int steps;
+	ssize_t r;
+	size_t n;
+
+	for (max1 = max0, steps = 0; max1 < UINTMAX_MAX && (max1 & (max1 + 1)); steps++)
+		max1 |= max1 >> steps;
+
+	do {
+		for (n = 0; n < sizeof(res); n += (size_t)r) {
+			r = getrandom(&((char *)&res)[n], sizeof(res) - n, 0);
+			if (r < 0)
+				eprintf("getrandom <buffer> %zu 0:", sizeof(res) - n);
+		}
+		res &= max1;
+	} while (res > max0);
+
+	return (intmax_t)res + min;
+}
+
+
+static void
+roll_dice(const struct die *dice, size_t n)
+{
+	intmax_t sum = 0, res, j;
+	size_t i;
+	for (i = 0; i < n; i++) {
+		for (j = 0; j < dice[i].count; j++) {
+			sum += res = random_int(dice[i].min, dice[i].max);
+			printf("Die roll: %ji\n", res);
+		}
+	}
+	if (n > 1 || (n == 1 && dice[0].count > 1)) {
+		printf("Sum: %ji\n", sum);
+	}
+}
+
+
+static int
+parse_dice(const char *s, struct die **dicep, size_t *ndicep)
+{
+	struct die *dice = NULL, *die;
+	size_t ndice = 0;
+	intmax_t min_sum = 0, max_sum = 0, num, i;
+
+	ndice = 0;
+
+	for (;;) {
+		while (*s == ' ' || *s == '\t')
+			s++;
+
+		if (!*s)
+			break;
+
+		if (!isdigit(*s) && *s != '-' && *s != 'd' && *s != 'D')
+			goto invalid;
+
+		dice = erealloc2(dice, ++ndice, sizeof(*dice));
+		die = &dice[ndice - 1];
+		die->count = 1;
+		die->min = 1;
+		num = 1;
+		if (*s == 'd' || *s == 'D')
+			goto at_d;
+		errno = 0;
+		num = strtoimax(s, (void *)&s, 0);
+		if (errno)
+			goto invalid;
+		if (*s == 'd' || *s == 'D') {
+		at_d:
+			s++;
+			if (num < 1)
+				goto invalid;
+			die->count = (size_t)num;
+			if (!isdigit(*s) && *s != '-')
+				goto invalid;
+			errno = 0;
+			num = strtoimax(s, (void *)&s, 0);
+			if (errno)
+				goto invalid;
+		}
+		die->max = num;
+		if (*s == '-') {
+			s++;
+			die->min = num;
+			errno = 0;
+			die->max = strtoimax(s, (void *)&s, 0);
+			if (errno)
+				goto invalid;
+		}
+		if (die->min > die->max)
+			goto invalid;
+
+		for (i = 0; i < die->count; i++) {
+			if (die->min < 0 && min_sum < INTMAX_MIN - die->min) {
+				printf("\033[31m%s\033[m\n", "Negative overflow in sum of minimums");
+				return -1;
+			}
+			if (die->min > 0 && min_sum > INTMAX_MAX - die->min) {
+				printf("\033[31m%s\033[m\n", "Positive overflow in sum of minimums");
+				return -1;
+			}
+			if (die->max < 0 && max_sum < INTMAX_MIN - die->max) {
+				printf("\033[31m%s\033[m\n", "Negative overflow in sum of maximums");
+				return -1;
+			}
+			if (die->max > 0 && max_sum > INTMAX_MAX - die->max) {
+				printf("\033[31m%s\033[m\n", "Positive overflow in sum of maximums");
+				return -1;
+			}
+			min_sum += die->min;
+			max_sum += die->max;
+		}
+
+		if (*s && *s != ',' && *s != ' ' && *s != '\t')
+			goto invalid;
+
+		if (*s == ',')
+			s++;
+	}
+
+	if (*s || !ndice)
+		goto invalid;
+
+	free(*dicep);
+	*dicep = dice;
+	*ndicep = ndice;
+
+	return 0;
+
+invalid:
+	printf("\033[31m%s\033[m\n", "Invalid input");
+	return -1;
+}
+
+
+int
+main(int argc, char *argv[])
+{
+	struct die *dice = NULL;
+	size_t ndice = 0;
+	char *line = NULL;
+	size_t size = 0;
+	ssize_t len;
+	int first;
+
+	NOFLAGS(argc);
+
+	for (first = 1;; first = 0) {
+	again:
+		if (first)
+			printf("\033[1m%s: \033[m", "Enter dice to roll");
+		else
+			printf("\033[1m%s\033[m (%s): ", "Enter dice to roll", "Leave empty to reroll");
+		fflush(stdout);
+		len = getdelim(&line, &size, '\n', stdin);
+		if (len < 0) {
+			printf("\n");
+			break;
+		}
+		if (len && line[len - 1] == '\n')
+			line[--len] = '\0';
+		if (!strcasecmp(line, "q") || !strcasecmp(line, "exit") || !strcasecmp(line, "quit"))
+			break;
+		if (!*line ? first : parse_dice(line, &dice, &ndice))
+			goto again;
+		roll_dice(dice, ndice);
+	}
+
+	if (ferror(stdin))
+		eprintf("getdelim <stdin>:");
+
+	free(dice);
+	free(line);
+	return 0;
+}