init lcd pixels, fix compile warnings

cli/emulator.c

@@ -22,7 +22,9 @@ int main(int argc, char *argv[])
     if (!rom_load(&rom, argv[1])) {
         printf("error loading rom\n");
         return 1;
-    }   
+    }
+
+    lcd_new(&lcd);
 
     // this might be too much abstraction but it'll let me
     // test the cpu, rom, and dmg independently and use the cpu

src/cpu.c

@@ -265,6 +265,9 @@ static u8 read_reg(struct cpu *cpu, int index)
         case 7: return cpu->a;
         default: cpu_panic(cpu);
     }
+
+    // unreachable
+    return 0;
 }
 
 static u8 write_reg(struct cpu *cpu, int index, u8 val)
@@ -280,6 +283,9 @@ static u8 write_reg(struct cpu *cpu, int index, u8 val)
         case 7: cpu->a = val; break;
         default: cpu_panic(cpu);
     }
+
+    // unreachable
+    return 0;
 }
 
 static void extended_insn(struct cpu *cpu, u8 insn)

src/lcd.c

@@ -1,4 +1,5 @@
 #include <stdio.h>
+#include <stdlib.h>
 
 #include "types.h"
 #include "lcd.h"
@@ -13,6 +14,12 @@ static void clear_bit(struct lcd *lcd, u16 addr, u8 bit)
     lcd_write(lcd, addr, lcd_read(lcd, addr) & ~(1 << bit));
 }
 
+void lcd_new(struct lcd *lcd)
+{
+    // todo < 8 bpp
+    lcd->pixels = malloc(LCD_WIDTH * LCD_HEIGHT);
+}
+
 u8 lcd_is_valid_addr(u16 addr)
 {
     return addr >= REG_LCD_BASE && addr <= REG_LCD_LAST;

src/lcd.h

@@ -30,6 +30,7 @@ struct lcd {
     u8 *pixels;
 };
 
+void lcd_new(struct lcd *lcd);
 u8 lcd_is_valid_addr(u16 addr);
 u8 lcd_read(struct lcd *lcd, u16 addr);
 void lcd_write(struct lcd *lcd, u16 addr, u8 value);