Add elog flush over semihosting

Signed-off-by: Martin Ribelotta <martinribelotta@gmail.com>

Author: martinribelotta

.gitignore

@@ -35,3 +35,6 @@
 *.lst
 *.nmp
 *.dep.mk
+
+# VSCode C debug
+.vscode/.cortex-debug.*.json

.vscode/launch.json

@@ -0,0 +1,25 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "cwd": "${workspaceRoot}",
+            "executable": "${workspaceFolder}/out/elog-test.elf",
+            "name": "Debug",
+            "request": "launch",
+            "type": "cortex-debug",
+            "servertype": "openocd",
+            "configFiles": [
+                "interface/stlink.cfg",
+                "target/stm32f1x.cfg"
+            ],
+            "openOCDLaunchCommands": [
+                "init",
+                "arm semihosting enable"
+            ],
+            "runToMain": true
+        }
+    ]
+}

inc/elog.h

@@ -33,12 +33,12 @@ typedef struct
     long data[0];
 } elog_entry_t;
 
-typedef void (elog_flush_func_t)(elog_entry_t *e);
+typedef void (elog_flush_func_t)(elog_entry_t *e, void *ctx);
 
 extern elog_t *elog_init(void *arena, size_t size);
 extern int elog_put(elog_t *log, const char *const msg, int n, long args[]);
 extern elog_entry_t *elog_peek(elog_t *log);
-extern void elog_flush(elog_t *log, elog_flush_func_t func);
+extern void elog_flush(elog_t *log, elog_flush_func_t func, void *ctx);
 
 #ifdef __cplusplus
 }

src/elog.c

@@ -26,13 +26,14 @@ int elog_put(elog_t *log, const char *const msg, int n, long args[])
     }
 }
 
-void elog_flush(elog_t *log, elog_flush_func_t func)
+void elog_flush(elog_t *log, elog_flush_func_t func, void *ctx)
 {
     long off = 0;
     while (off < log->offset) {
-        elog_entry_t *e = ((elog_entry_t*) log->buffer + off);
-        func(e);
-        off += e->len;
+        elog_entry_t *e = ((elog_entry_t*) (log->buffer + off));
+        size_t incr = sizeof(elog_entry_t) + e->len * sizeof(long);
+        off += incr;
+        func(e, ctx);
     }
     log->offset = 0;
 }

src/main.c

@@ -6,6 +6,12 @@
 static elog_t *logger;
 static char arena[1024];
 
+static void log_to_semihost(elog_entry_t *e, void *ctx)
+{
+    int fd = *(int*) ctx;
+    write(fd, e, sizeof(elog_entry_t) + e->len * sizeof(long));
+}
+
 int main()
 {
     static const char const b[] = "Hello world\n";
@@ -23,5 +29,12 @@ int main()
         ELOG(logger, "Error opening archive\n");
         writestr("Error opening file");
     }
+    int log_fd = open("bin.log", SYS_OPEN_WOB);
+    if (log_fd != -1) {
+        elog_flush(logger, log_to_semihost, &log_fd);
+        close(log_fd);
+    } else {
+        writestr("cannot open bin log for write");
+    }
     return 0;
 }