Created getcontrol/respcontrol

Hopefully there are no copy-paste bugs

groundStation/src/backend/bitwise.h

 #ifndef _bitwise_h
 #define _bitwise_h
 
+#include <string.h>
+#include <stdint.h>
+
 /* Bit shifting for endianness of 16-bit numbers */
 #define LSByte16(x) ((x) & 0xff)
 #define MSByte16(x) (((x) >> 8) & 0xff)
@@ -12,18 +15,44 @@
  * to do this involves actually implementing
  * IEEE 754 in software to do so
  */
-#define FloatByte1(x) (((char *) &(x))[0])
-#define FloatByte2(x) (((char *) &(x))[1])
-#define FloatByte3(x) (((char *) &(x))[2])
-#define FloatByte4(x) (((char *) &(x))[3])
-
-/* This is so much UB it hurts to write */
-#define BytesToFloat(f, b1, b2, b3, b4) \
-	do {                                \
-		((char *) &(f))[0] = (b1);      \
-		((char *) &(f))[1] = (b2);      \
-		((char *) &(f))[2] = (b3);      \
-		((char *) &(f))[3] = (b4);      \
-	} while (0);
+static inline uint8_t FloatByte1(float f)
+{
+	char arr[4];
+	memcpy(arr, &f, 4);
+	return arr[0];
+}
+
+static inline uint8_t FloatByte2(float f)
+{
+	char arr[4];
+	memcpy(arr, &f, 4);
+	return arr[1];
+}
+
+static inline uint8_t FloatByte3(float f)
+{
+	char arr[4];
+	memcpy(arr, &f, 4);
+	return arr[2];
+}
+
+static inline uint8_t FloatByte4(float f)
+{
+	char arr[4];
+	memcpy(arr, &f, 4);
+	return arr[3];
+}
+
+static inline float BytesToFloat(uint8_t b1, uint8_t b2, uint8_t b3, uint8_t b4)
+{
+	char arr[4];
+	arr[0] = b1;
+	arr[1] = b2;
+	arr[2] = b3;
+	arr[3] = b4;
 
+	float f;
+	memcpy(&f, arr, 4);
+	return f;
+}
 #endif

groundStation/src/backend/getcontrol.c

+#include "getcontrol.h"
+#include "commands.h"
+#include "bitwise.h"
+
+#include <sys/types.h>
+
+enum GetcontrolData {
+	CTRL_ID,
+	CTRLVAL_ID,
+	VAL_1,
+	VAL_2,
+	VAL_3,
+	VAL_4,
+	GC_DATA_SIZE
+};
+
+/* Creates data and metadata for a respcontrol packet
+ * Returns data size.
+ */
+ssize_t EncodeGetcontrol(
+        struct metadata * m,        /* data_len and msg_type will be populated*/
+        uint8_t * data,             /* Output buffer */
+        size_t data_size,           /* Max buffer size */
+        const struct controller_message * cm)       /* Message to encode */
+{
+	m->msg_type = GETCONTROL_ID;
+	m->data_len = GC_DATA_SIZE;
+
+	if (data_size < GC_DATA_SIZE) {
+		return -1;
+	}
+
+	data[CTRL_ID] = cm->id;
+	data[CTRLVAL_ID] = cm->value_id;
+	data[VAL_1] = FloatByte1(cm->value);
+	data[VAL_2] = FloatByte2(cm->value);
+	data[VAL_3] = FloatByte3(cm->value);
+	data[VAL_4] = FloatByte4(cm->value);
+
+	return GC_DATA_SIZE;
+}
+
+/* Decode a metadata and data to populate a controller.
+ * Returns 0 on success, -1 on failure.
+ */
+int DecodeGetcontrol(
+        struct controller_message * cm,     /* Decoded controller message */
+        const struct metadata * m,          /* Metadata to aid in decoding */
+        const uint8_t * data)               /* Data to decode */
+{
+	if (m->data_len < GC_DATA_SIZE) {
+		return -1;
+	}
+	if (m->msg_type != GETCONTROL_ID) {
+		return -1;
+	}
+
+
+	cm->id = data[CTRL_ID];
+	cm->value_id = data[CTRLVAL_ID];
+	cm->value = BytesToFloat(data[VAL_1], data[VAL_2],
+			data[VAL_3], data[VAL_4]);
+
+	return 0;
+}

groundStation/src/backend/getcontrol.h

+#ifndef _getcontrol_h
+#define _getcontrol_h
+
+#include "packet.h"
+#include "controller.h"
+
+#include <sys/types.h>
+
+
+/* Creates data and metadata for a getcontrol packet.
+ * Returns data size.
+ */
+ssize_t EncodeGetcontrol(
+		struct metadata *m, /* Out */
+		uint8_t *data,      /* Out */
+		size_t data_size,   /* Data buffer max size */
+		const struct controller_message *cm); /* Value is not used; only IDs */
+
+/* Decode a metadata and data to populate a message
+ * Returns 0 on success, -1 on failure
+ */
+int DecodeGetcontrol(
+		struct controller_message *cm, /* Out. Value is undefined */
+		const struct metadata *m,      /* In */
+		const uint8_t * data);         /* In */
+
+
+#endif

groundStation/src/backend/respcontrol.c

+#include "respcontrol.h"
+#include "commands.h"
+#include "bitwise.h"
+
+#include <sys/types.h>
+
+enum RespcontrolData {
+	CTRL_ID,
+	CTRLVAL_ID,
+	VAL_1,
+	VAL_2,
+	VAL_3,
+	VAL_4,
+	RC_DATA_SIZE
+};
+
+/* Creates data and metadata for a respcontrol packet
+ * Returns data size.
+ */
+ssize_t EncodeRespcontrol(
+        struct metadata * m,        /* data_len and msg_type will be populated*/
+        uint8_t * data,             /* Output buffer */
+        size_t data_size,           /* Max buffer size */
+        const struct controller_message * cm)       /* Message to encode */
+{
+	m->msg_type = RESPCONTROL_ID;
+	m->data_len = RC_DATA_SIZE;
+
+	if (data_size < RC_DATA_SIZE) {
+		return -1;
+	}
+
+	data[CTRL_ID] = cm->id;
+	data[CTRLVAL_ID] = cm->value_id;
+	data[VAL_1] = FloatByte1(cm->value);
+	data[VAL_2] = FloatByte2(cm->value);
+	data[VAL_3] = FloatByte3(cm->value);
+	data[VAL_4] = FloatByte4(cm->value);
+
+	return RC_DATA_SIZE;
+}
+
+/* Decode a metadata and data to populate a controller.
+ * Returns 0 on success, -1 on failure.
+ */
+int DecodeRespcontrol(
+        struct controller_message * cm,     /* Decoded controller message */
+        const struct metadata * m,          /* Metadata to aid in decoding */
+        const uint8_t * data)               /* Data to decode */
+{
+	if (m->data_len < RC_DATA_SIZE) {
+		return -1;
+	}
+	if (m->msg_type != RESPCONTROL_ID) {
+		return -1;
+	}
+
+
+	cm->id = data[CTRL_ID];
+	cm->value_id = data[CTRLVAL_ID];
+	cm->value = BytesToFloat(data[VAL_1], data[VAL_2],
+			data[VAL_3], data[VAL_4]);
+
+	return 0;
+}

groundStation/src/backend/respcontrol.h

+#ifndef _respcontrol_h
+#define _respcontrol_h
+
+#include "packet.h"
+#include "controller.h"
+
+#include <sys/types.h>
+
+
+/* Creates data and metadata for a respcontrol packet.
+ * Returns data size.
+ */
+ssize_t EncodeRespcontrol(
+		struct metadata *m, /* Out */
+		uint8_t *data,      /* Out */
+		size_t data_size,   /* Data buffer max size */
+		const struct controller_message *cm); /* In */
+
+/* Decode a metadata and data to populate a message
+ * Returns 0 on success, -1 on failure
+ */
+int DecodeRespcontrol(
+		struct controller_message *cm, /* Out */
+		const struct metadata *m,      /* In */
+		const uint8_t * data);         /* In */
+
+
+#endif

groundStation/src/backend/setcontrol.c

@@ -55,13 +55,11 @@ int DecodeSetcontrol(
 		return -1;
 	}
 
-	/* Would violate strict aliasing to work directly on the struct member */
-	float val;
-	BytesToFloat(val, data[VAL_1], data[VAL_2], data[VAL_3], data[VAL_4]);
 
 	cm->id = data[CTRL_ID];
 	cm->value_id = data[CTRLVAL_ID];
-	cm->value = val;
+	cm->value = BytesToFloat(data[VAL_1], data[VAL_2],
+			data[VAL_3], data[VAL_4]);
 
 	return 0;
 }