From 6d4ad089c5b758ad8af4f68bf385a26ec4e9653a Mon Sep 17 00:00:00 2001
From: Thomas Albers Raviola <thomas@thomaslabs.org>
Date: Thu, 21 Nov 2024 15:55:03 +0100
Subject: Initial commit

---
 src/tty.c | 164 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 164 insertions(+)
 create mode 100644 src/tty.c

(limited to 'src/tty.c')

diff --git a/src/tty.c b/src/tty.c
new file mode 100644
index 0000000..f9413b4
--- /dev/null
+++ b/src/tty.c
@@ -0,0 +1,164 @@
+#include <tft.h>
+#include <zeta.h>
+#include <tty.h>
+
+struct color {
+	uint8_t r, g, b;
+};
+
+static unsigned int row = 0;
+static unsigned int col = 0;
+
+// Index of first row inside buf
+static volatile uint8_t head = 0;
+
+// TTY's current contents
+static volatile uint8_t buf[TTY_HEIGHT][TTY_WIDTH];
+
+static volatile struct color bg_color = {0x00, 0x00, 0x00};
+static volatile struct color fg_color = {0xFF, 0xFB, 0x00};
+
+extern const uint8_t font[97][8];
+
+
+static uint8_t cursor = 0;
+static uint8_t timer = 0;
+
+void
+blink_cursor(void) __critical __interrupt(3)
+{
+	if (++timer >= 75) {
+		uint8_t i;
+
+		tft_set_area(8 * col, 8 * row, 8, 8);
+		tft_ram_wr();
+
+		if ((cursor ^= 1)) {
+			for (i = 0; i < 64; ++i)
+				tft_pixel(fg_color.r, fg_color.g, fg_color.b);
+		} else {
+			for (i = 0; i < 64; ++i)
+				tft_pixel(bg_color.r, bg_color.g, bg_color.b);
+		}
+		timer = 0;
+	}
+}
+
+static void
+draw(u8 c)
+{
+	u8 i, j;
+	const u8 *chr;
+
+	if (c < ' ')
+		return;
+
+	chr = font[c - ' '];
+
+	tft_ram_wr();
+
+	for (i = 0; i < 8; ++i) {
+		u8 row = chr[i];
+		for (j = 0; j < 8; ++j) {
+			if (row & 1)
+				tft_pixel(fg_color.r, fg_color.g, fg_color.b);
+			else
+				tft_pixel(bg_color.r, bg_color.g, bg_color.b);
+			row >>= 1;
+		}
+	}
+}
+
+static void
+scroll(void)
+{
+	uint16_t i, j;
+	head = (head + 1) % TTY_HEIGHT;
+
+	for (i = head; i < TTY_HEIGHT; ++i) {
+		for (j = 0; j < TTY_WIDTH; ++j) {
+			tft_set_area(8 * j, 8 * (i - head), 8, 8);
+			draw(buf[i][j]);
+		}
+	}
+
+	for (i = 0; i < head - 1; ++i) {
+		for (j = 0; j < TTY_WIDTH; ++j) {
+			tft_set_area(8 * j, 8 * (TTY_HEIGHT - head + i), 8, 8);
+			draw(buf[i][j]);
+		}
+	}
+
+	for (j = 0; j < TTY_WIDTH; ++j) {
+		tft_set_area(8 * j, 8 * (TTY_HEIGHT - 1), 8, 8);
+		draw(' ');
+	}
+}
+
+static void
+newline(void)
+{
+	if (++row >= TTY_HEIGHT) {
+		row = TTY_HEIGHT - 1;
+		scroll();
+	}
+}
+
+static void
+advance(void)
+{
+	if (++col >= TTY_WIDTH) {
+		newline();
+		col = 0;
+	}
+}
+
+void
+addch(char c)
+{
+	switch (c) {
+	case '\b':
+		if (col != 0)
+			--col;
+		return;
+
+	case '\r':
+		col = 0;
+		return;
+
+	case '\n':
+		newline();
+		return;
+	}
+
+	tft_set_area(8 * col, 8 * row, 8, 8);
+
+	draw(c);
+
+	buf[(head + row) % TTY_HEIGHT][col] = c;
+	advance();
+}
+
+void
+setcur(unsigned int ncol, unsigned int nrow)
+{
+	col = ncol;
+	row = nrow;
+}
+
+void
+swap_colors(void)
+{
+	struct color tmp = {fg_color.r, fg_color.g, fg_color.b};
+	fg_color = bg_color;
+	bg_color = tmp;
+}
+
+void
+addstr(const char *str)
+{
+	while (*str) {
+		addch(*str);
+		++str;
+	}
+}
-- 
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