Add a proper type for bit arrays

- Define type bitArrayElement_t as uint32_t.
- Add BITARRAY_DECLARE() macro, which declares a bit array given
the number of desired bits, taking care of aligment and rounding
up its size to a multiple of 32.
- Change bit array functions to accept bitarrayElement_t* rather
than void*.
- Replace bit array declarations with BITARRAY_DECLARE() macro
- Add BITARRAY_FIND_FIRST_SET() macro to call bitArrayFindFirstSet()
without explicitely specifying its size.
- Update comments in bitarray.h to reflect these changes.

src/main/common/bitarray.c

@@ -24,17 +24,17 @@
 // to find set bits faster.
 #define BITARRAY_BIT_OP(array, bit, op) ((array)[(bit) / (sizeof((array)[0]) * 8)] op ((1u<<31) >> ((bit) % (sizeof((array)[0]) * 8))))
 
-bool bitArrayGet(const void *array, unsigned bit)
+bool bitArrayGet(const bitarrayElement_t *array, unsigned bit)
 {
     return BITARRAY_BIT_OP((uint32_t*)array, bit, &);
 }
 
-void bitArraySet(void *array, unsigned bit)
+void bitArraySet(bitarrayElement_t *array, unsigned bit)
 {
     BITARRAY_BIT_OP((uint32_t*)array, bit, |=);
 }
 
-void bitArrayClr(void *array, unsigned bit)
+void bitArrayClr(bitarrayElement_t *array, unsigned bit)
 {
     BITARRAY_BIT_OP((uint32_t*)array, bit, &=~);
 }
@@ -52,7 +52,7 @@ __attribute__((always_inline)) static inline uint8_t __CLZ(uint32_t val)
 #endif
 }
 
-int bitArrayFindFirstSet(const void *array, unsigned start, size_t size)
+int bitArrayFindFirstSet(const bitarrayElement_t *array, unsigned start, size_t size)
 {
     const uint32_t *ptr = (uint32_t*)array;
     const uint32_t *end = ptr + (size / 4);

src/main/common/bitarray.h

@@ -20,16 +20,22 @@
 
 /*
  * These functions expect array to be 4-byte aligned since they alias array
- * to an uint32_t pointer in order to work fast.
+ * to an uint32_t pointer in order to work fast. Use the BITARRAY_DECLARE()
+ * macro to declare a bit array that can be safely used by them.
  */
 
-bool bitArrayGet(const void *array, unsigned bit);
-void bitArraySet(void *array, unsigned bit);
-void bitArrayClr(void *array, unsigned bit);
+typedef uint32_t bitarrayElement_t;
+
+#define BITARRAY_DECLARE(name, bits) bitarrayElement_t name[(bits + 31) / 32]
+
+bool bitArrayGet(const bitarrayElement_t *array, unsigned bit);
+void bitArraySet(bitarrayElement_t *array, unsigned bit);
+void bitArrayClr(bitarrayElement_t *array, unsigned bit);
+
 // Returns the first set bit with pos >= start_bit, or -1 if all bits
-// are zero.
-// Note that size must indicate the size of array in bytes.
-//
-// WARNING: This function only works for arrays where size is a multiple
-// of 4.
-int bitArrayFindFirstSet(const void *array, unsigned start_bit, size_t size);
+// are zero. Note that size must indicate the size of array in bytes.
+// In most cases, you should use the BITARRAY_FIND_FIRST_SET() macro
+// to call this function.
+int bitArrayFindFirstSet(const bitarrayElement_t *array, unsigned start_bit, size_t size);
+
+#define BITARRAY_FIND_FIRST_SET(array, start_bit) bitArrayFindFirstSet(array, start_bit, sizeof(array))

src/main/drivers/max7456.c

@@ -183,7 +183,7 @@ uint16_t maxScreenSize = VIDEO_BUFFER_CHARS_PAL;
 // in screenIsDirty to upgrade only changed chars this solution
 // is faster than redrawing the whole screen on each frame
 static uint8_t screenBuffer[VIDEO_BUFFER_CHARS_PAL] ALIGNED(4);
-static uint8_t screenIsDirty[VIDEO_BUFFER_CHARS_PAL/8] ALIGNED(4) = {0,};
+static BITARRAY_DECLARE(screenIsDirty, VIDEO_BUFFER_CHARS_PAL);
 
 //max chars to update in one idle
 #define MAX_CHARS2UPDATE    5

src/main/fc/fc_msp.c

@@ -417,7 +417,7 @@ static void packBoxModeFlags(boxBitmask_t * mspBoxModeFlags)
     memset(mspBoxModeFlags, 0, sizeof(boxBitmask_t));
     for (uint32_t i = 0; i < activeBoxIdCount; i++) {
         if (activeBoxes[activeBoxIds[i]]) {
-            bitArraySet(mspBoxModeFlags, i);
+            bitArraySet(mspBoxModeFlags->bits, i);
         }
     }
 }

src/main/fc/rc_modes.c

@@ -66,7 +66,7 @@ bool isUsingNavigationModes(void)
 
 bool IS_RC_MODE_ACTIVE(boxId_e boxId)
 {
-    return bitArrayGet(&rcModeActivationMask, boxId);
+    return bitArrayGet(rcModeActivationMask.bits, boxId);
 }
 
 void rcModeUpdate(boxBitmask_t *newState)
@@ -124,13 +124,13 @@ void updateActivatedModes(void)
             if (modeActivationOperatorConfig()->modeActivationOperator == MODE_OPERATOR_AND) {
                 // AND the conditions
                 if (activeConditionCountPerMode[modeIndex] == specifiedConditionCountPerMode[modeIndex]) {
-                    bitArraySet(&newMask, modeIndex);
+                    bitArraySet(newMask.bits, modeIndex);
                 }
             }
             else {
                 // OR the conditions
                 if (activeConditionCountPerMode[modeIndex] > 0) {
-                    bitArraySet(&newMask, modeIndex);
+                    bitArraySet(newMask.bits, modeIndex);
                 }
             }
         }

src/main/fc/rc_modes.h

@@ -19,6 +19,8 @@
 
 #include <stdbool.h>
 
+#include "common/bitarray.h"
+
 #include "config/parameter_group.h"
 
 typedef enum {
@@ -58,7 +60,7 @@ typedef enum {
 } boxId_e;
 
 // type to hold enough bits for CHECKBOX_ITEM_COUNT. Struct used for value-like behavior
-typedef struct boxBitmask_s { uint32_t bits[(CHECKBOX_ITEM_COUNT + 31) / 32]; } boxBitmask_t;
+typedef struct boxBitmask_s { BITARRAY_DECLARE(bits, CHECKBOX_ITEM_COUNT); } boxBitmask_t;
 
 #define MAX_MODE_ACTIVATION_CONDITION_COUNT 20