1 files changed, 91 insertions, 0 deletions
diff --git a/shed_io.c b/shed_io.c
new file mode 100644
index 0000000..17aee8e
--- /dev/null
+++ b/shed_io.c
@@ -0,0 +1,91 @@
+#define _POSIX_C_SOURCE 200809L
+#include <string.h>
+#include <unistd.h>
+#include "shed.h"
+
+void shed_replace_char(struct buffer *b, char c)
+{
+	if (b->pos >= (size_t)b->nread) {
+		shed_insert_char(b, c);
+		return;
+	}
+	b->buf[b->pos] = c;
+	write(STDOUT_FILENO, &c, 1);
+	b->pos++;
+}
+
+void shed_insert_char(struct buffer *b, char c)
+{
+	if (b->pos >= (size_t)b->nread) {
+		b->buf[b->pos] = c;
+		write(STDOUT_FILENO, &c, 1);
+	} else {
+		size_t shift = b->nread - b->pos;
+		char *start = b->buf + b->pos;
+		memmove(start + 1, start, shift);
+		*start = c;
+
+		char back[shift];
+		memset(back, '\b', shift);
+		write(STDOUT_FILENO, start, shift + 1);
+		write(STDOUT_FILENO, back, shift);
+	}
+
+	b->pos++;
+	b->nread++;
+}
+
+void shed_remove_char(struct buffer *b, int forward)
+{
+	/* TODO: don't forward delete past the end */
+	if (forward) {
+		write(STDOUT_FILENO, b->buf + b->pos, 1);
+		b->pos++;
+	}
+
+	if (b->pos == 0) {
+		return;
+	}
+
+	b->pos--;
+
+	char *start = b->buf + b->pos;
+	size_t shift = (size_t)b->nread - b->pos;
+
+	b->nread--;
+
+	for (size_t i = 0; i < shift; i++) {
+		start[i] = start[i + 1];
+	}
+	start[shift] = '\0';
+
+	char back[shift];
+	memset(back, '\b', shift);
+	write(STDOUT_FILENO, back, 1);
+	write(STDOUT_FILENO, start, shift);
+	write(STDOUT_FILENO, " \b", 2);
+	write(STDOUT_FILENO, back, shift - 1);
+}
+
+void shed_move_cursor(struct buffer *b, int move)
+{
+	if (move > 0) {
+		int maxfwd = (int)(b->nread - b->pos);
+		if (move > maxfwd) {
+			move = maxfwd;
+		}
+		write(STDOUT_FILENO, b->buf + b->pos, move);
+		b->pos += move;
+	}
+
+	if (move < 0) {
+		size_t len = (size_t)(-move);
+		if (len > b->pos) {
+			len = b->pos;
+		}
+		char back[len];
+		memset(back, '\b', len);
+		write(STDOUT_FILENO, back, len);
+		b->pos -= len;
+	}
+}