sys/fmt: Added submodule fmt_table

print_col_u32_dec() / print_col_s32_dec() can be used to print an
uint32_t / int32_t as a column of the given width

makefiles/pseudomodules.inc.mk

@@ -12,6 +12,7 @@ PSEUDOMODULES += cpu_check_address
 PSEUDOMODULES += ecc_%
 PSEUDOMODULES += emb6_router
 PSEUDOMODULES += event_%
+PSEUDOMODULES += fmt_%
 PSEUDOMODULES += gnrc_ipv6_default
 PSEUDOMODULES += gnrc_ipv6_router
 PSEUDOMODULES += gnrc_ipv6_router_default

sys/Makefile.dep

@@ -2,6 +2,10 @@ ifneq (,$(filter eepreg,$(USEMODULE)))
   FEATURES_REQUIRED += periph_eeprom
 endif
 
+ifneq (,$(filter fmt_table,$(USEMODULE)))
+  USEMODULE += fmt
+endif
+
 ifneq (,$(filter i2c_scan,$(USEMODULE)))
   FEATURES_REQUIRED += periph_i2c
 endif

sys/fmt/Makefile

@@ -1 +1,7 @@
+# exclude submodule sources from *.c wildcard source selection
+SRC := $(filter-out table.c,$(wildcard *.c))
+
+# enable submodules
+SUBMODULES := 1
+
 include $(RIOTBASE)/Makefile.base

sys/fmt/table.c

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2019 Otto-von-Guericke-Universität Magdeburg
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     sys_fmt_table
+ * @{
+ *
+ * @file
+ * @brief       Implementation of the table extensions of the string formatting
+ *              library
+ *
+ * @author      Marian Buschsieweke <marian.buschsieweke@ovgu.de>
+ *
+ * @}
+ */
+
+#include <assert.h>
+#include <stdarg.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <string.h>
+
+#include "fmt.h"
+
+static const char fmt_table_spaces[16] = "                ";
+
+/**
+ * @brief Prints @p fill_size bytes of the given pattern, repeating the
+ *        pattern if needed
+ * @param pat       Pattern to print
+ * @param pat_size  Size of the pattern in bytes
+ * @param fill_size Number of bytes to print (if bigger than @p pat_size, the
+ *                  pattern will be repeated)
+ *
+ * E.g. `print_pattern("ab", 2, 5);` will print `ababa` to the console.
+ * This can be used to fill table columns with spaces, draw lines, etc.
+ */
+static void print_pattern(const char *pat, size_t pat_size, size_t fill_size)
+{
+    while (fill_size > pat_size) {
+        print(pat, pat_size);
+    }
+
+    print(pat, fill_size);
+}
+
+void print_col_u32_dec(uint32_t number, size_t width)
+{
+    char sbuf[10]; /* "4294967295" */
+    size_t slen;
+
+    slen = fmt_u32_dec(sbuf, number);
+    if (width > slen) {
+        print_pattern(fmt_table_spaces, sizeof(fmt_table_spaces), width - slen);
+    }
+    print(sbuf, slen);
+}
+
+void print_col_s32_dec(int32_t number, size_t width)
+{
+    char sbuf[11]; /* "-2147483648" */
+    size_t slen;
+
+    slen = fmt_s32_dec(sbuf, number);
+    if (width > slen) {
+        print_pattern(fmt_table_spaces, sizeof(fmt_table_spaces), width - slen);
+    }
+    print(sbuf, slen);
+}

sys/include/fmt_table.h

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2019 Otto-von-Guericke-Universität Magdeburg
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @defgroup    sys_fmt_table Table extension of the string formatting API (fmt_table)
+ * @ingroup     sys_fmt
+ * @brief       Provides utilities to print tables.
+ *
+ * \note The print functions in this library do not buffer any output.
+ * Mixing calls to standard @c printf from stdio.h with the @c print_xxx
+ * functions in fmt, especially on the same output line, may cause garbled
+ * output.
+ *
+ * @{
+ *
+ * @file
+ * @brief       Table extension of the string formatting API
+ *
+ * @author      Marian Buschsieweke <marian.buschsieweke@ovgu.de>
+ */
+
+#ifndef FMT_TABLE_H
+#define FMT_TABLE_H
+
+#include <stdint.h>
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Print a table column with the given number as decimal
+ * @param number    Number to print in the column
+ * @param width     Width of the column
+ */
+void print_col_u32_dec(uint32_t number, size_t width);
+
+/**
+ * @brief Print a table column with the given number as decimal
+ * @param number    Number to print in the column
+ * @param width     Width of the column
+ */
+void print_col_s32_dec(int32_t number, size_t width);
+
+#ifdef __cplusplus
+}
+#endif
+
+/** @} */
+#endif /* FMT_TABLE_H */