Tool for IPC command headers

IPC-command-headers.md

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+Services use command headers for IPC (inter-process communications).
+Those have been changed to use the function IPC_MakeHeader (3ds/ipc.h) instead of the raw header values.
+
+A small tool to convert from raw to more human understandable values and code is available.
+Here is an example of output : 
+
+```
+$>IPCParseHeader 0x080b0102
+0x80B0102 =>
+        id: 0x80B
+        normal: 4
+        translate: 2
+IPC_MakeHeader(0x80B,4,2); // 0x80B0102
+```
+
+source :
+
+```c
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+typedef uint8_t u8;
+typedef uint16_t u16;
+typedef uint32_t u32;
+typedef uint64_t u64;
+
+/**
+ * @brief Command header to be used for IPC
+ * @param normal_params    Size of the normal parameters in words. Up to 63.
+ * @param translate_params Size of the translate parameters in words. Up to 63.
+ *
+ * Normal parameters are sent directly to the process while the translate parameters might go through modifications and checks by the kernel.
+ * The translate parameters are described by headers generated with the IPC_Desc_* functions.
+ *
+ * @note While #normal_params is equivalent to the number of normal parameters, #translate_params includes the size occupied by the translate parameters headers.
+ */
+static inline u32 IPC_MakeHeader(u16 command_id, unsigned normal_params, unsigned translate_params)
+{
+	return ((u32) command_id << 16) | (((u32) normal_params & 0x3F) << 6) | (((u32) translate_params & 0x3F) << 0);
+}
+
+
+int main(int argc, char* argv[])
+{
+    assert(argc == 2);
+    unsigned header = (unsigned)strtol(argv[1], NULL, 0);
+    
+    unsigned id = header>>16;
+    unsigned normal =header >> 6 & 0x3F;
+    unsigned translate = header&0x3F;
+    printf("0x%X =>\n"
+                   "\tid: 0x%X\n"
+                   "\tnormal: %d\n"
+                   "\ttranslate: %d\n"
+            ,header,id,normal,translate );
+    printf("IPC_MakeHeader(0x%X,%d,%d); // 0x%X\n"
+            ,id,normal,translate,header);
+    assert(header == IPC_MakeHeader(id,normal,translate));
+    return 0;
+}
+```
+