libsigrok-internal.h: add helper macro to read floats from unaligend memory.

src/libsigrok-internal.h

@@ -113,6 +113,20 @@
                   ((unsigned)((const uint8_t*)(x))[1] <<  8) |  \
                    (unsigned)((const uint8_t*)(x))[0]))
 
+/**
+ * Read a 32 bits big endian float out of memory.
+ * @param x a pointer to the input memory
+ * @return the corresponding float
+ */
+#define RBFL(x)  ((union { uint32_t u; float f; }) { .u = RB32(x) }.f)
+
+/**
+ * Read a 32 bits little endian float out of memory.
+ * @param x a pointer to the input memory
+ * @return the corresponding float
+ */
+#define RLFL(x)  ((union { uint32_t u; float f; }) { .u = RL32(x) }.f)
+
 /**
  * Write a 8 bits unsigned integer to memory.
  * @param p a pointer to the output memory
@@ -156,6 +170,20 @@
                          ((uint8_t*)(p))[2] = (uint8_t)((x)>>16); \
                          ((uint8_t*)(p))[3] = (uint8_t)((x)>>24); } while (0)
 
+/**
+ * Write a 32 bits float to memory stored as big endian.
+ * @param p a pointer to the output memory
+ * @param x the input float
+ */
+#define WBFL(p, x)  WB32(p, (union { uint32_t u; float f; }) { .f = x }.u)
+
+/**
+ * Write a 32 bits float to memory stored as little endian.
+ * @param p a pointer to the output memory
+ * @param x the input float
+ */
+#define WLFL(p, x)  WL32(p, (union { uint32_t u; float f; }) { .f = x }.u)
+
 /* Portability fixes for FreeBSD. */
 #ifdef __FreeBSD__
 #define LIBUSB_CLASS_APPLICATION 0xfe