start working on gui

src/CMakeLists.txt

@@ -0,0 +1,4 @@
+
+add_library(decn decn/decn.c)
+
+add_library(calc main.c calc.c utils.c lcd_emulator.c key.c)

src/lcd_emulator.c

@@ -0,0 +1,93 @@
+/*
+ * lcd_emulator.c
+ *
+ *  Created on: Apr 1, 2019
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include "lcd.h"
+
+#define CR 13 // \r
+#define TAB 9 // \n
+
+static int lcd_row, lcd_col;
+static char lcd_buf[MAX_ROWS][MAX_CHARS_PER_LINE];
+
+void LCD_Open(void){
+
+}
+
+void LCD_Clear(void){
+	lcd_row=0;
+	lcd_col=0;
+	for (int i = 0; i < MAX_ROWS; i++){
+		for (int j = 0; j < MAX_CHARS_PER_LINE; j++){
+			lcd_buf[i][j] = 0;
+		}
+	}
+}
+
+void LCD_GoTo(unsigned int row, unsigned int col){
+	if (row < MAX_ROWS && col < MAX_CHARS_PER_LINE){
+		lcd_row = row;
+		lcd_col = col;
+	} else {
+		printf("LCD_GoTo(%u, %u) out of range\n", lcd_row, lcd_col);
+	}
+}
+
+static void to_row(unsigned char row_to){
+	if (row_to == 0){
+		lcd_row = 0;
+	} else {
+		lcd_row = 1;
+	}
+	lcd_col = 0;
+}
+
+void LCD_OutString(const char *string, uint8_t max_chars) {
+	const char *s;
+	for (s = string; *s && max_chars > 0; s++, max_chars--) {
+		TERMIO_PutChar(*s);
+	}
+}
+
+short TERMIO_PutChar(unsigned char letter) {
+	if (letter == CR || letter == '\n') {
+		LCD_Clear();
+	} else if (letter == TAB || letter == '\t') {
+		if (lcd_row == 0) {
+			to_row(1);
+		} else {
+			to_row(0);
+		}
+	} else {
+		lcd_buf[lcd_row][lcd_col] = letter;
+		lcd_col++;
+		if (lcd_col > MAX_CHARS_PER_LINE) {
+			if (lcd_row == 0) {
+				to_row(1);
+			} else {
+				to_row(0);
+			}
+		}
+	}
+
+	return 1;
+}
+
+void LCD_ClearToEnd(uint8_t curr_row){
+	while (lcd_col != 0 && lcd_row == curr_row){
+		TERMIO_PutChar(' ');
+	}
+}
+
+void LCD_OutNibble(uint8_t x){
+	x &= 0xf; //ensure only bottom nibble
+	if (x <= 9){
+		TERMIO_PutChar(x + '0');
+	} else {
+		TERMIO_PutChar(x - 10 + 'a');
+	}
+}