print: Added size_t print format specifier

- Added `PRIuSIZE`, `PRIxSIZE`, etc. to `architecure.h` - Changed `CODING_CONVENTIONS.md` regarding `size_t` printing Co-authored-by: Marian Buschsieweke <[email protected]>
jcjhot · Dec 21, 2023 · b5a4380 · b5a4380
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Showing 2 changed files with 50 additions and 3 deletions.
diff --git a/CODING_CONVENTIONS.md b/CODING_CONVENTIONS.md
@@ -301,9 +301,7 @@ Some solutions to correctly handle compilation warnings.
 Solution for string formatting errors:
 
 * When printing a `size_t`
-    * use `%u` and cast the variable to `(unsigned)` because `newlib-nano` does
-      not support `%zu`
-      [example](https://github.com/RIOT-OS/RIOT/blob/e19f6463c09fc22c76c5b855799054cf27a697f1/tests/sizeof_tcb/main.c#L34)
+    * use `PRIuSIZE` from `architecture.h` because `newlib-nano` does not support `%zu`
 * When printing an `unsigned char/uint8_t`
     * Use `%u` because `newlib-nano` does not support `%hu/PRIu8`
       [example](https://github.com/RIOT-OS/RIOT/pull/4851)

diff --git a/sys/include/architecture.h b/sys/include/architecture.h
@@ -26,6 +26,7 @@
 
 #include <stdint.h>
 #include <inttypes.h>
+#include <limits.h>
 
 #include "architecture_arch.h"
 
@@ -105,6 +106,54 @@ typedef uintptr_t   uinttxtptr_t;
 #define PRIxTXTPTR PRIxPTR
 #endif
 
+#if DOXYGEN
+/**
+ * @brief   Architecture specific modifier used for printing sizes
+ */
+#define PRI_SIZE_T_MODIFIER /* implementation defined */
+#elif (UINT_MAX == SIZE_MAX)
+#define PRI_SIZE_T_MODIFIER ""
+#elif (ULONG_MAX == SIZE_MAX)
+#define PRI_SIZE_T_MODIFIER "l"
+#else
+#error Unsupported size_t length
+#endif
+
+/**
+ * @brief   Macro holding the format specifier to print an `ssize_t` variable
+ *          in decimal representation.
+ */
+#define PRIdSIZE PRI_SIZE_T_MODIFIER "d"
+/**
+ * @brief   Macro holding the format specifier to print an `ssize_t` variable.
+ *
+ * Same as @ref PRIdSIZE for output. When used for input (e.g. in `scanf()`),
+ * `PRIiSIZE` will also accept hexadecimal and octal numbers if prefixed by
+ * `0x` or `0`, respectively.
+ */
+#define PRIiSIZE PRI_SIZE_T_MODIFIER "i"
+/**
+ * @brief   Macro holding the format specifier to print an `ssize_t` variable
+ *          in octal representation.
+ * `0x` or `0`, respectively.
+ */
+#define PRIoSIZE PRI_SIZE_T_MODIFIER "o"
+/**
+ * @brief   Macro holding the format specifier to print an `size_t` variable
+ *          in decimal representation.
+ */
+#define PRIuSIZE PRI_SIZE_T_MODIFIER "u"
+/**
+ * @brief   Macro holding the format specifier to print an `size_t` variable
+ *          in hexadecimal representation (e.g. `2a` for 42).
+ */
+#define PRIxSIZE PRI_SIZE_T_MODIFIER "x"
+/**
+ * @brief   Macro holding the format specifier to print an `size_t` variable
+ *          in hexadecimal representation (e.g. `2A` for 42).
+ */
+#define PRIXSIZE PRI_SIZE_T_MODIFIER "X"
+
 /**
  * @brief   Type qualifier to use to align data on word boundaries
  *