logging: more CN workarounds

components/logging/cn_mavlink_stubs.h

@@ -3,7 +3,60 @@
 // CN-compatible stubs for the MAVLink functions we use.
 
 #include <stdint.h>
-#include <mavlink/mavlink_types.h>
+
+// From `mavlink/mavlink_types.h`
+
+struct __mavlink_message {
+    // TODO: Make this an incomplete type.  Currently, this placeholder
+    // definition is necessary because CN errors on incomplete types.
+    uint8_t _dummy;
+};
+typedef struct __mavlink_message mavlink_message_t;
+
+const char* _mav_payload_impl(const mavlink_message_t* msg);
+#define _MAV_PAYLOAD(msg) (_mav_payload_impl(msg))
+
+typedef enum {
+	MAVLINK_TYPE_CHAR     = 0,
+	MAVLINK_TYPE_UINT8_T  = 1,
+	MAVLINK_TYPE_INT8_T   = 2,
+	MAVLINK_TYPE_UINT16_T = 3,
+	MAVLINK_TYPE_INT16_T  = 4,
+	MAVLINK_TYPE_UINT32_T = 5,
+	MAVLINK_TYPE_INT32_T  = 6,
+	MAVLINK_TYPE_UINT64_T = 7,
+	MAVLINK_TYPE_INT64_T  = 8,
+	MAVLINK_TYPE_FLOAT    = 9,
+	MAVLINK_TYPE_DOUBLE   = 10
+} mavlink_message_type_t;
+
+#define MAVLINK_MAX_FIELDS 64
+
+typedef struct __mavlink_field_info {
+	const char *name;                 // name of this field
+        const char *print_format;         // printing format hint, or NULL
+        mavlink_message_type_t type;      // type of this field
+        unsigned int array_length;        // if non-zero, field is an array
+        unsigned int wire_offset;         // offset of each field in the payload
+        unsigned int structure_offset;    // offset in a C structure
+} mavlink_field_info_t;
+
+// note that in this structure the order of fields is the order
+// in the XML file, not necessary the wire order
+typedef struct __mavlink_message_info {
+	uint32_t msgid;                                        // message ID
+	const char *name;                                      // name of the message
+	unsigned num_fields;                                   // how many fields in this message
+	mavlink_field_info_t fields[MAVLINK_MAX_FIELDS];       // field information
+} mavlink_message_info_t;
+
+struct __mavlink_status {
+    // TODO: Make this an incomplete type.  Currently, this placeholder
+    // definition is necessary because CN errors on incomplete types.
+    uint8_t _dummy;
+};
+typedef struct __mavlink_status  mavlink_status_t;
+
 
 // From `mavlink/mavlink_get_info.h`
 const mavlink_message_info_t *mavlink_get_message_info(const mavlink_message_t *msg);

components/logging/cn_stubs.h

@@ -0,0 +1,44 @@
+#pragma once
+
+// CN-compatible stubs for libc functions we use.
+
+#include <sys/types.h>
+
+#include <time.h>
+// Additional functions that are missing from CN's `time.h`
+void tzset(void);
+size_t strftime(char *s, size_t max,
+        const char *restrict format, const struct tm *restrict tm);
+struct tm *localtime_r(const time_t *restrict timep,
+        struct tm *restrict result);
+
+
+// From `stdio.h`
+
+#ifndef WAR_CN_309
+// not possible to call this due to CN issue #309
+// this spec isn't right but can't develop it at all without #309
+void perror(const char *msg);
+/*$ spec perror(pointer msg);
+    requires take mi = Owned<char>(msg);
+    ensures take mo = Owned<char>(msg);
+      mi == mo;
+$*/
+#else
+# define perror(...) 0
+#endif
+
+#define printf(...) 0
+#define vsnprintf(...) 0
+
+
+// Helpers for dispatching based on number of arguments.  Taken from
+// https://stackoverflow.com/a/16683147
+
+#define CAT( A, B ) A ## B
+#define SELECT( NAME, NUM ) CAT( NAME ## _, NUM )
+
+#define GET_COUNT( _1, _2, _3, _4, _5, _6 /* ad nauseam */, COUNT, ... ) COUNT
+#define VA_SIZE( ... ) GET_COUNT( __VA_ARGS__, 6, 5, 4, 3, 2, 1 )
+
+#define VA_SELECT( NAME, ... ) SELECT( NAME, VA_SIZE(__VA_ARGS__) )(__VA_ARGS__)

components/logging/output.c

@@ -1,19 +1,21 @@
 // Code for converting a MAVLink message into log output.
 
-#include <stdio.h>
 #include <stdarg.h>
 #include <stdlib.h>
-#include <time.h>
 #include <inttypes.h>
+#include <sys/types.h>
 
 #ifndef CN_ENV
+# include <stdio.h>
+# include <time.h>
 // `mavlink_get_info.h` uses `offsetof`, but doesn't include the header
 // `stddef.h` that provides it.  We include the header here so `offsetof` will
 // be available.
 # include <stddef.h>
 # include <mavlink/all/mavlink.h>
 # include <mavlink/mavlink_get_info.h>
 #else
+# include "cn_stubs.h"
 # include "cn_mavlink_stubs.h"
 #endif
 
@@ -31,6 +33,9 @@ void buffer_init(struct buffer* b) {
     b->buf[0] = '\0';
 }
 
+
+#ifndef CN_ENV
+
 void buffer_printf(struct buffer* b, const char* fmt, ...) {
     va_list args;
     va_start(args, fmt);
@@ -47,6 +52,37 @@ void buffer_printf(struct buffer* b, const char* fmt, ...) {
     va_end(args);
 }
 
+#else
+
+// Dispatch by argument count to different variants of `buffer_printf`.
+//
+// Conveniently, we never call `buffer_printf` twice with the same number of
+// arguments but with different argument types.  If this changes, we could
+// potentially handle it by making all variants take `void*` and wrap each
+// variant in a macro that inserts the necessary casts.
+
+#define buffer_printf(...) VA_SELECT(buffer_printf, __VA_ARGS__)
+
+void buffer_printf_2(struct buffer* b, const char* fmt) {
+    // TODO
+}
+
+void buffer_printf_3(struct buffer* b, const char* fmt, const char* arg0) {
+    // TODO
+}
+
+void buffer_printf_4(struct buffer* b, const char* fmt, int arg0, const char* arg1) {
+    // TODO
+}
+
+void buffer_printf_5(struct buffer* b, const char* fmt,
+        int arg0, const char* arg1, int64_t arg2) {
+    // TODO
+}
+
+#endif
+
+
 void buffer_strftime(struct buffer* b, const char* fmt, const struct tm* tm) {
     size_t avail = sizeof(b->buf) - b->pos;
     size_t ret = strftime(b->buf + b->pos, avail, fmt, tm);
@@ -131,12 +167,17 @@ void handle_message(const mavlink_message_t* msg) {
                             *(int64_t*)(payload + field->wire_offset));
                     break;
                 case MAVLINK_TYPE_FLOAT:
+// CN doesn't support floats.
+#ifndef CN_ENV
                     buffer_printf(&buf, "%c %s=%f", delim, field->name,
                             *(float*)(payload + field->wire_offset));
+#endif
                     break;
                 case MAVLINK_TYPE_DOUBLE:
+#ifndef CN_ENV
                     buffer_printf(&buf, "%c %s=%lf", delim, field->name,
                             *(double*)(payload + field->wire_offset));
+#endif
                     break;
             }
         }

components/logging/output.h

@@ -1,5 +1,9 @@
 #pragma once
 
-#include <mavlink/mavlink_types.h>
+#ifndef CN_ENV
+# include <mavlink/mavlink_types.h>
+#else
+# include "cn_mavlink_stubs.h"
+#endif
 
 void handle_message(const mavlink_message_t* msg);