Display: introduce font.h, paraphrase handling distinct fonts.

While this could also be done properly now, with a couple of
additional fonts, this would require quite some time. However,
it's more important to have at least one display working now,
rather than having a ton of sophisticated eye-candy, which isn't
even user-visible, because the upper layers are still missing.

font.c

@@ -0,0 +1,16 @@
+
+/** \file
+
+  \brief Font broker.
+
+  Here we map generic font variables to the actually used font. This is done in
+  a rather primitive way by having the same variable name in all font variants
+  and wrapping each font in the corresponding #ifdef.
+*/
+
+#include "font.h"
+
+#define TEACUP_C_INCLUDE
+#include "font_8x4.c"
+//#include "font_ another.c"
+#undef TEACUP_C_INCLUDE

font.h

@@ -0,0 +1,35 @@
+
+#ifndef _FONT_H
+#define _FONT_H
+
+#include <stdint.h>
+#include "arduino.h"  // For PROGMEM.
+
+/**
+  So far we have only one font and no choice for fonts in Configtool,
+  so just paraphrase handling of distinct fonts.
+*/
+
+//#if defined DISPLAY_FONT_8X4
+
+  #define FONT_ROWS             8
+  #define FONT_COLUMNS          4
+  #define FONT_SYMBOL_SPACE     1
+  #define FONT_IS_PROPORTIONAL
+
+//#elif defined DISPLAY_FONT_...another font
+
+  // ... ...
+
+//#endif
+
+typedef struct {
+  #ifdef FONT_IS_PROPORTIONAL
+    uint8_t columns;
+  #endif
+  uint8_t data[FONT_COLUMNS];
+} symbol_t;
+
+extern const symbol_t PROGMEM font[];
+
+#endif /* _FONT_H */

font_8x4.c

@@ -8,9 +8,12 @@
   removed from font.
 */
 
-#include "font_8x4.h"
+// So far we have no #define DISPLAY_FONT_... in Configtool.
+#if defined TEACUP_C_INCLUDE /* && defined DISPLAY_FONT_8x4 */
 
-const symbol_t PROGMEM font_8x4[] = {
+#include "font.h"
+
+const symbol_t PROGMEM font[] = {
   {2, {0x00, 0x00, 0x00, 0x00}},  /* space */
   {3, {0x0C, 0x5E, 0x0C, 0x00}},  /* excl_mark */
   {3, {0x03, 0x00, 0x03, 0x00}},  /* quot_mark */
@@ -113,3 +116,5 @@ const symbol_t PROGMEM font_8x4[] = {
   {4, {0x02, 0x01, 0x02, 0x01}},  /* tilde */
   {4, {0x00, 0x00, 0x00, 0x00}}   /* del */
 };
+
+#endif /* TEACUP_C_INCLUDE && DISPLAY_FONT_8x4 */

font_8x4.h

@@ -1,19 +0,0 @@
-
-#ifndef _FONT_8x4_H
-#define _FONT_8x4_H
-
-#include <stdint.h>
-#include "arduino.h"  // For PROGMEM.
-
-#define FONT_ROWS 8
-#define FONT_COLUMNS 4
-#define FONT_SYMBOL_SPACE 1
-
-typedef struct {
-  uint8_t columns;
-  uint8_t data[FONT_COLUMNS];
-} symbol_t;
-
-extern const symbol_t PROGMEM font_8x4[];
-
-#endif /* _FONT_8x4_H */

i2c_test.c

@@ -16,7 +16,7 @@
 #include <string.h>
 #include "config_wrapper.h"
 #include "displaybus.h"
-#include "font_8x4.h"
+#include "font.h"
 
 
 #define DISPLAY_I2C_ADDRESS        (0x3C << 1)
@@ -96,8 +96,8 @@ static void i2c_test(void) {
     uint8_t index = (uint8_t)*message - 0x20;
 
     // Send the character bitmap.
-    for (i = 0; i < pgm_read_byte(&font_8x4[index].columns); i++) {
+    for (i = 0; i < pgm_read_byte(&font[index].columns); i++) {
-      displaybus_write(pgm_read_byte(&font_8x4[index].data[i]), 0);
+      displaybus_write(pgm_read_byte(&font[index].data[i]), 0);
     }
     // Send space between characters.
     for (i = 0; i < FONT_SYMBOL_SPACE; i++) {