[kernel] Move the logger from kutil into kernel

Part one of a series of code moves. The kutil library is not very
useful, as most of its code is kernel-specific. This was originally for
testing purposes, but that can be achieved in other ways with the
current build system. I find this mostly creates a strange division in
the kernel code.

Instead, I'm going to move everything kernel-specific to actually be in
the kernel, and replace kutil with just 'util' for generic utility code
I want to share.

This commit:

- Moves the logger into the kernel.
- Updates the 'printf' library used from mpaland/printf to
  eyalroz/printf and moved it into the kernel, as it's only used by the
  logger in kutil.
- Removes some other unused kutil headers from some files, to help
  future code rearrangement.

Note that the (now redundant-seeming) log.cpp/h in kernel is currently
still there - these files are more about log output than the logging
system, and will get replaced once I add user-space log output.

configs/base.yaml

@@ -26,7 +26,8 @@ variables:
     "-Wpointer-arith", "-Wno-attributes", "-Wno-sign-compare", "-Wno-multichar",
     "-Wno-div-by-zero", "-Wno-endif-labels", "-Wno-pragmas", "-Wno-format-extra-args",
     "-Wno-unused-result", "-Wno-deprecated-declarations", "-Wno-unused-function",
-    "-Wno-address-of-packed-member", "-Wno-invalid-offsetof", "-Werror" ]
+    "-Wno-address-of-packed-member", "-Wno-invalid-offsetof", "-Wno-format-nonliteral",
+    "-Werror" ]
 
   asflags: [
     "-DVERSION_MAJOR=${version_major}",

configs/kernel-debug.yaml

@@ -24,6 +24,8 @@ variables:
     "-D__JSIX__",
     "-U__linux",
     "-U__linux__",
+    "-DPRINTF_ALIAS_STANDARD_FUNCTION_NAMES=1",
+    "-DPRINTF_INCLUDE_CONFIG_H=1",
 
     "-isystem${source_root}/sysroot/include",
     "-isystem${source_root}/src/libraries/libc/include",

other_software.md

@@ -35,14 +35,16 @@ Boost Software license:
 
 ## printf
 
-jsix uses Marco Paland's tiny [printf][] library for its `*printf()` functions,
+jsix uses Marco Paland and Eyal Rozenberg's tiny [printf][] library for
-which is also released under the terms of the MIT license:
+in-kernel `*printf()` functions, which is also released under the terms of the
+MIT license:
 
-[printf]: https://github.com/mpaland/printf
+[printf]: https://github.com/eyalroz/printf
 
 > The MIT License (MIT)
 >
 > Copyright (c) 2014 Marco Paland
+> Copyright (c) 2021 Eyal Rozenberg
 >
 > Permission is hereby granted, free of charge, to any person obtaining a copy
 > of this software and associated documentation files (the "Software"), to deal

src/kernel/acpi_tables.h

@@ -4,7 +4,6 @@
 #include <stdint.h>
 
 #include "enum_bitfields.h"
-#include "kutil/coord.h"
 #include "kutil/misc.h"
 
 struct acpi_table_header

src/kernel/console.cpp

@@ -1,8 +1,6 @@
-#include "kutil/coord.h"
-#include "kutil/guid.h"
 #include "kutil/memory.h"
 #include "kutil/no_construct.h"
-#include "kutil/printf.h"
+#include "printf/printf.h"
 #include "console.h"
 #include "serial.h"
 
@@ -81,6 +79,6 @@ void console::vprintf(const char *fmt, va_list args)
 {
     static const unsigned buf_size = 256;
     char buffer[buf_size];
-    vsnprintf_(buffer, buf_size, fmt, args);
+    vsnprintf(buffer, buf_size, fmt, args);
     puts(buffer);
 }

src/kernel/interrupts.cpp

@@ -1,7 +1,7 @@
 #include <stdint.h>
 
 #include "kernel_memory.h"
-#include "kutil/printf.h"
+#include "printf/printf.h"
 
 #include "cpu.h"
 #include "device_manager.h"
@@ -130,7 +130,7 @@ isr_handler(cpu_state *regs)
                 break;
 
             snprintf(message, sizeof(message),
-                "Page fault: %016llx%s%s%s%s%s", cr2,
+                "Page fault: %016lx%s%s%s%s%s", cr2,
                 (regs->errorcode & 0x01) ? " present" : "",
                 (regs->errorcode & 0x02) ? " write" : "",
                 (regs->errorcode & 0x04) ? " user" : "",
@@ -153,7 +153,7 @@ isr_handler(cpu_state *regs)
         return;
 
     default:
-        snprintf(message, sizeof(message), "Unknown interrupt 0x%x", regs->interrupt);
+        snprintf(message, sizeof(message), "Unknown interrupt 0x%lx", regs->interrupt);
         kassert(false, message);
     }
 
@@ -170,7 +170,7 @@ irq_handler(cpu_state *regs)
     if (! device_manager::get().dispatch_irq(irq)) {
         char message[100];
         snprintf(message, sizeof(message),
-            "Unknown IRQ: %d (vec 0x%x)", irq, regs->interrupt);
+            "Unknown IRQ: %d (vec 0x%lx)", irq, regs->interrupt);
         kassert(false, message);
     }
 

src/kernel/kernel.module

@@ -26,6 +26,7 @@ kernel = module("kernel",
         "interrupts.s",
         "io.cpp",
         "log.cpp",
+        "logger.cpp",
         "memory_bootstrap.cpp",
         "msr.cpp",
         "objects/channel.cpp",
@@ -38,6 +39,7 @@ kernel = module("kernel",
         "page_table.cpp",
         "page_tree.cpp",
         "pci.cpp",
+        "printf/printf.c",
         "scheduler.cpp",
         "serial.cpp",
         "syscalls/channel.cpp",

src/kernel/log.cpp

@@ -28,6 +28,9 @@ output_log(log::area_t area, log::level severity, const char *message)
     cons->set_color();
 }
 
+// For printf.c
+extern "C" void putchar_(char c) {}
+
 static void
 log_flush()
 {

src/kernel/log.h

@@ -1,9 +1,6 @@
 #pragma once
 
-#include "kutil/logger.h"
+#include "logger.h"
-
-namespace log = kutil::log;
-namespace logs = kutil::logs;
 
 void logger_init();
 void logger_clear_immediate();

src/kernel/logger.cpp

@@ -1,10 +1,10 @@
 #include "kutil/assert.h"
 #include "kutil/constexpr_hash.h"
-#include "kutil/logger.h"
 #include "kutil/memory.h"
-#include "kutil/printf.h"
+#include "printf/printf.h"
+
+#include "logger.h"
 
-namespace kutil {
 namespace logs {
 #define LOG(name, lvl) \
     const log::area_t name = #name ## _h; \
@@ -170,4 +170,3 @@ void fatal(area_t area, const char *fmt, ...)
 }
 
 } // namespace log
-} // namespace kutil

src/kernel/logger.h

@@ -8,7 +8,6 @@
 #include "kutil/bip_buffer.h"
 #include "kutil/spinlock.h"
 
-namespace kutil {
 namespace log {
 
 using area_t = uint8_t;
@@ -124,6 +123,8 @@ void warn (area_t area, const char *fmt, ...);
 void error(area_t area, const char *fmt, ...);
 void fatal(area_t area, const char *fmt, ...);
 
+extern log::logger &g_logger;
+
 } // namespace log
 
 namespace logs {
@@ -131,5 +132,3 @@ namespace logs {
 #include "j6/tables/log_areas.inc"
 #undef LOG
 } // namespace logs
-
-} // namespace kutil

src/kernel/panic.serial/display.cpp

@@ -1,6 +1,7 @@
+#include "printf/printf.h"
+
 #include "cpu.h"
 #include "display.h"
-#include "kutil/printf.h"
 #include "serial.h"
 #include "symbol_table.h"
 
@@ -25,7 +26,7 @@ print_header(
     out.write(":");
 
     char linestr[6];
-    snprintf(linestr, sizeof(linestr), "%d", line);
+    snprintf(linestr, sizeof(linestr), "%ld", line);
     out.write(linestr);
 
     out.write("\n \e[0;31m===================================================================================\n");
@@ -56,7 +57,7 @@ print_reg(serial_port &out, const char *name, uint64_t val, const char *color)
 {
     char message[512];
 
-    snprintf(message, sizeof(message), " \e[0;%sm%-3s %016llx\e[0m", color, name, val);
+    snprintf(message, sizeof(message), " \e[0;%sm%-3s %016lx\e[0m", color, name, val);
     out.write(message);
 }
 
@@ -102,3 +103,6 @@ print_cpu_state(serial_port &out, const cpu_state &regs)
 }
 
 } // namespace panic
+
+// For printf.c
+extern "C" void putchar_(char c) {}

src/kernel/panic.serial/serial.module

@@ -11,6 +11,7 @@ panic = module("panic.serial",
         "main.cpp",
         "serial.cpp",
         "symbol_table.cpp",
+        "../printf/printf.c",
     ])
 
 panic.variables['ldflags'] = ["${ldflags}", "-T", "${source_root}/src/kernel/panic.serial/panic.serial.ld"]

src/kernel/printf/printf.h

@@ -0,0 +1,151 @@
+/**
+ * @author (c) Eyal Rozenberg <eyalroz1@gmx.com>
+ *             2021, Haifa, Palestine/Israel
+ * @author (c) Marco Paland (info@paland.com)
+ *             2014-2019, PALANDesign Hannover, Germany
+ *
+ * @note Others have made smaller contributions to this file: see the
+ * contributors page at https://github.com/eyalroz/printf/graphs/contributors
+ * or ask one of the authors.
+ *
+ * @brief Small stand-alone implementation of the printf family of functions
+ * (`(v)printf`, `(v)s(n)printf` etc., geared towards use on embedded systems with
+ * a very limited resources.
+ *
+ * @note the implementations are thread-safe; re-entrant; use no functions from
+ * the standard library; and do not dynamically allocate any memory.
+ *
+ * @license The MIT License (MIT)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef PRINTF_H_
+#define PRINTF_H_
+
+#include <stdarg.h>
+#include <stddef.h>
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef __GNUC__
+# define ATTR_PRINTF(one_based_format_index, first_arg) \
+__attribute__((format(__printf__, (one_based_format_index), (first_arg))))
+# define ATTR_VPRINTF(one_based_format_index) ATTR_PRINTF(one_based_format_index, 0)
+#else
+# define ATTR_PRINTF(one_based_format_index, first_arg)
+# define ATTR_VPRINTF(one_based_format_index)
+#endif
+
+#ifndef PRINTF_ALIAS_STANDARD_FUNCTION_NAMES
+#define PRINTF_ALIAS_STANDARD_FUNCTION_NAMES 0
+#endif
+
+#if PRINTF_ALIAS_STANDARD_FUNCTION_NAMES
+# define printf_    printf
+# define sprintf_   sprintf
+# define vsprintf_  vsprintf
+# define snprintf_  snprintf
+# define vsnprintf_ vsnprintf
+# define vprintf_   vprintf
+#endif
+
+/**
+ * Output a character to a custom device like UART, used by the printf() function
+ * This function is declared here only. You have to write your custom implementation somewhere
+ * @param character Character to output
+ */
+void putchar_(char character);
+
+
+/**
+ * Tiny printf implementation
+ * You have to implement putchar_ if you use printf()
+ * To avoid conflicts with the regular printf() API it is overridden by macro defines
+ * and internal underscore-appended functions like printf_() are used
+ * @param format A string that specifies the format of the output
+ * @return The number of characters that are written into the array, not counting the terminating null character
+ */
+int printf_(const char* format, ...) ATTR_PRINTF(1, 2);
+
+
+/**
+ * Tiny sprintf/vsprintf implementation
+ * Due to security reasons (buffer overflow) YOU SHOULD CONSIDER USING (V)SNPRINTF INSTEAD!
+ * @param buffer A pointer to the buffer where to store the formatted string. MUST be big enough to store the output!
+ * @param format A string that specifies the format of the output
+ * @param va A value identifying a variable arguments list
+ * @return The number of characters that are WRITTEN into the buffer, not counting the terminating null character
+ */
+int  sprintf_(char* buffer, const char* format, ...) ATTR_PRINTF(2, 3);
+int vsprintf_(char* buffer, const char* format, va_list va) ATTR_VPRINTF(2);
+
+
+/**
+ * Tiny snprintf/vsnprintf implementation
+ * @param buffer A pointer to the buffer where to store the formatted string
+ * @param count The maximum number of characters to store in the buffer, including a terminating null character
+ * @param format A string that specifies the format of the output
+ * @param va A value identifying a variable arguments list
+ * @return The number of characters that COULD have been written into the buffer, not counting the terminating
+ *         null character. A value equal or larger than count indicates truncation. Only when the returned value
+ *         is non-negative and less than count, the string has been completely written.
+ */
+int  snprintf_(char* buffer, size_t count, const char* format, ...) ATTR_PRINTF(3, 4);
+int vsnprintf_(char* buffer, size_t count, const char* format, va_list va) ATTR_VPRINTF(3);
+
+
+/**
+ * Tiny vprintf implementation
+ * @param format A string that specifies the format of the output
+ * @param va A value identifying a variable arguments list
+ * @return The number of characters that are WRITTEN into the buffer, not counting the terminating null character
+ */
+int vprintf_(const char* format, va_list va) ATTR_VPRINTF(1);
+
+
+/**
+ * printf/vprintf with output function
+ * You may use this as dynamic alternative to printf() with its fixed _putchar() output
+ * @param out An output function which takes one character and an argument pointer
+ * @param arg An argument pointer for user data passed to output function
+ * @param format A string that specifies the format of the output
+ * @param va A value identifying a variable arguments list
+ * @return The number of characters that are sent to the output function, not counting the terminating null character
+ */
+int fctprintf(void (*out)(char character, void* arg), void* arg, const char* format, ...) ATTR_PRINTF(3, 4);
+int vfctprintf(void (*out)(char character, void* arg), void* arg, const char* format, va_list va) ATTR_VPRINTF(3);
+
+#ifdef __cplusplus
+}
+#endif
+
+#if PRINTF_ALIAS_STANDARD_FUNCTION_NAMES
+# undef printf_
+# undef sprintf_
+# undef vsprintf_
+# undef snprintf_
+# undef vsnprintf_
+# undef vprintf_
+#endif
+
+#endif  // PRINTF_H_

src/kernel/printf/printf_config.h

@@ -0,0 +1,10 @@
+#pragma once
+
+// \file printf_config.h
+// Configuration for eyalroz/printf
+
+#define PRINTF_SUPPORT_DECIMAL_SPECIFIERS       0
+#define PRINTF_SUPPORT_EXPONENTIAL_SPECIFIERS   0
+#define PRINTF_SUPPORT_WRITEBACK_SPECIFIER      0
+#define PRINTF_SUPPORT_LONG_LONG                1
+#define PRINTF_ALIAS_STANDARD_FUNCTION_NAMES    1

src/libraries/kutil/include/kutil/printf.h

@@ -1,96 +0,0 @@
-///////////////////////////////////////////////////////////////////////////////
-// \author (c) Marco Paland (info@paland.com)
-//             2014-2018, PALANDesign Hannover, Germany
-//
-// \license The MIT License (MIT)
-//
-// Permission is hereby granted, free of charge, to any person obtaining a copy
-// of this software and associated documentation files (the "Software"), to deal
-// in the Software without restriction, including without limitation the rights
-// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-// copies of the Software, and to permit persons to whom the Software is
-// furnished to do so, subject to the following conditions:
-// 
-// The above copyright notice and this permission notice shall be included in
-// all copies or substantial portions of the Software.
-// 
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-// THE SOFTWARE.
-//
-// \brief Tiny printf, sprintf and snprintf implementation, optimized for speed on
-//        embedded systems with a very limited resources.
-//        Use this instead of bloated standard/newlib printf.
-//        These routines are thread safe and reentrant.
-//
-///////////////////////////////////////////////////////////////////////////////
-
-#ifndef _PRINTF_H_
-#define _PRINTF_H_
-
-#include <stdarg.h>
-#include <stddef.h>
-
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-/**
- * Tiny printf implementation
- * You have to implement _putchar if you use printf()
- * To avoid conflicts with the regular printf() API it is overridden by macro defines
- * and internal underscore-appended functions like printf_() are used
- * \param format A string that specifies the format of the output
- * \return The number of characters that are written into the array, not counting the terminating null character
- */
-#define printf printf_
-int printf_(const char* format, ...);
-
-
-/**
- * Tiny sprintf implementation
- * Due to security reasons (buffer overflow) YOU SHOULD CONSIDER USING (V)SNPRINTF INSTEAD!
- * \param buffer A pointer to the buffer where to store the formatted string. MUST be big enough to store the output!
- * \param format A string that specifies the format of the output
- * \return The number of characters that are WRITTEN into the buffer, not counting the terminating null character
- */
-#define sprintf sprintf_
-int sprintf_(char* buffer, const char* format, ...);
-
-
-/**
- * Tiny snprintf/vsnprintf implementation
- * \param buffer A pointer to the buffer where to store the formatted string
- * \param count The maximum number of characters to store in the buffer, including a terminating null character
- * \param format A string that specifies the format of the output
- * \return The number of characters that are WRITTEN into the buffer, not counting the terminating null character
- *         If the formatted string is truncated the buffer size (count) is returned
- */
-#define snprintf  snprintf_
-#define vsnprintf vsnprintf_
-int  snprintf_(char* buffer, size_t count, const char* format, ...);
-int vsnprintf_(char* buffer, size_t count, const char* format, va_list va);
-
-
-/**
- * printf with output function
- * You may use this as dynamic alternative to printf() with its fixed _putchar() output
- * \param out An output function which takes one character and an argument pointer
- * \param arg An argument pointer for user data passed to output function
- * \param format A string that specifies the format of the output
- * \return The number of characters that are sent to the output function, not counting the terminating null character
- */
-int fctprintf(void (*out)(char character, void* arg), void* arg, const char* format, ...);
-
-
-#ifdef __cplusplus
-}
-#endif
-
-
-#endif  // _PRINTF_H_

src/libraries/kutil/kutil.module

@@ -7,8 +7,6 @@ module("kutil",
         "assert.cpp",
         "bip_buffer.cpp",
         "heap_allocator.cpp",
-        "logger.cpp",
         "memory.cpp",
-        "printf.c",
         "spinlock.cpp",
     ])

src/libraries/kutil/printf.c

@@ -1,767 +0,0 @@
-///////////////////////////////////////////////////////////////////////////////
-// \author (c) Marco Paland (info@paland.com)
-//             2014-2019, PALANDesign Hannover, Germany
-//
-// \license The MIT License (MIT)
-//
-// Permission is hereby granted, free of charge, to any person obtaining a copy
-// of this software and associated documentation files (the "Software"), to deal
-// in the Software without restriction, including without limitation the rights
-// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-// copies of the Software, and to permit persons to whom the Software is
-// furnished to do so, subject to the following conditions:
-//
-// The above copyright notice and this permission notice shall be included in
-// all copies or substantial portions of the Software.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-// THE SOFTWARE.
-//
-// \brief Tiny printf, sprintf and (v)snprintf implementation, optimized for speed on
-//        embedded systems with a very limited resources. These routines are thread
-//        safe and reentrant!
-//        Use this instead of the bloated standard/newlib printf cause these use
-//        malloc for printf (and may not be thread safe).
-//
-///////////////////////////////////////////////////////////////////////////////
-
-#include <stdbool.h>
-#include <stdint.h>
-
-#include "kutil/printf.h"
-
-#define PRINTF_DISABLE_SUPPORT_FLOAT
-
-// define this globally (e.g. gcc -DPRINTF_INCLUDE_CONFIG_H ...) to include the
-// printf_config.h header file
-// default: undefined
-#ifdef PRINTF_INCLUDE_CONFIG_H
-#include "printf_config.h"
-#endif
-
-
-// 'ntoa' conversion buffer size, this must be big enough to hold one converted
-// numeric number including padded zeros (dynamically created on stack)
-// default: 32 byte
-#ifndef PRINTF_NTOA_BUFFER_SIZE
-#define PRINTF_NTOA_BUFFER_SIZE    32U
-#endif
-
-// 'ftoa' conversion buffer size, this must be big enough to hold one converted
-// float number including padded zeros (dynamically created on stack)
-// default: 32 byte
-#ifndef PRINTF_FTOA_BUFFER_SIZE
-#define PRINTF_FTOA_BUFFER_SIZE    32U
-#endif
-
-// support for the floating point type (%f)
-// default: activated
-#ifndef PRINTF_DISABLE_SUPPORT_FLOAT
-#define PRINTF_SUPPORT_FLOAT
-#endif
-
-// support for the long long types (%llu or %p)
-// default: activated
-#ifndef PRINTF_DISABLE_SUPPORT_LONG_LONG
-#define PRINTF_SUPPORT_LONG_LONG
-#endif
-
-// support for the ptrdiff_t type (%t)
-// ptrdiff_t is normally defined in <stddef.h> as long or long long type
-// default: activated
-#ifndef PRINTF_DISABLE_SUPPORT_PTRDIFF_T
-#define PRINTF_SUPPORT_PTRDIFF_T
-#endif
-
-///////////////////////////////////////////////////////////////////////////////
-
-// internal flag definitions
-#define FLAGS_ZEROPAD   (1U <<  0U)
-#define FLAGS_LEFT      (1U <<  1U)
-#define FLAGS_PLUS      (1U <<  2U)
-#define FLAGS_SPACE     (1U <<  3U)
-#define FLAGS_HASH      (1U <<  4U)
-#define FLAGS_UPPERCASE (1U <<  5U)
-#define FLAGS_CHAR      (1U <<  6U)
-#define FLAGS_SHORT     (1U <<  7U)
-#define FLAGS_LONG      (1U <<  8U)
-#define FLAGS_LONG_LONG (1U <<  9U)
-#define FLAGS_PRECISION (1U << 10U)
-
-
-// output function type
-typedef void (*out_fct_type)(char character, void* buffer, size_t idx, size_t maxlen);
-
-
-// wrapper (used as buffer) for output function type
-typedef struct {
-  void  (*fct)(char character, void* arg);
-  void* arg;
-} out_fct_wrap_type;
-
-
-// internal buffer output
-static inline void _out_buffer(char character, void* buffer, size_t idx, size_t maxlen)
-{
-  if (idx < maxlen) {
-    ((char*)buffer)[idx] = character;
-  }
-}
-
-
-// internal null output
-static inline void _out_null(char character, void* buffer, size_t idx, size_t maxlen)
-{
-  (void)character; (void)buffer; (void)idx; (void)maxlen;
-}
-
-#ifdef PRINTF_PUTCHAR_FUNC
-// internal screen ouput wrapper
-static inline void _out_char(char character, void* buffer, size_t idx, size_t maxlen)
-{
-  (void)buffer; (void)idx; (void)maxlen;
-  if (character) {
-    PRINTF_PUTCHAR_FUNC (character);
-  }
-}
-#endif
-
-// internal output function wrapper
-static inline void _out_fct(char character, void* buffer, size_t idx, size_t maxlen)
-{
-  (void)idx; (void)maxlen;
-  if (character) {
-    // buffer is the output fct pointer
-    ((out_fct_wrap_type*)buffer)->fct(character, ((out_fct_wrap_type*)buffer)->arg);
-  }
-}
-
-
-// internal secure strlen
-// \return The length of the string (excluding the terminating 0) limited by 'maxsize'
-static inline unsigned int _strnlen_s(const char* str, size_t maxsize)
-{
-  const char* s;
-  for (s = str; *s && maxsize--; ++s);
-  return (unsigned int)(s - str);
-}
-
-
-// internal test if char is a digit (0-9)
-// \return true if char is a digit
-static inline bool _is_digit(char ch)
-{
-  return (ch >= '0') && (ch <= '9');
-}
-
-
-// internal ASCII string to unsigned int conversion
-static unsigned int _atoi(const char** str)
-{
-  unsigned int i = 0U;
-  while (_is_digit(**str)) {
-    i = i * 10U + (unsigned int)(*((*str)++) - '0');
-  }
-  return i;
-}
-
-
-// internal itoa format
-static size_t _ntoa_format(out_fct_type out, char* buffer, size_t idx, size_t maxlen, char* buf, size_t len, bool negative, unsigned int base, unsigned int prec, unsigned int width, unsigned int flags)
-{
-  const size_t start_idx = idx;
-
-  // pad leading zeros
-  if (!(flags & FLAGS_LEFT)) {
-    if (width && (flags & FLAGS_ZEROPAD) && (negative || (flags & (FLAGS_PLUS | FLAGS_SPACE)))) {
-      width--;
-    }
-    while ((len < prec) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
-      buf[len++] = '0';
-    }
-    while ((flags & FLAGS_ZEROPAD) && (len < width) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
-      buf[len++] = '0';
-    }
-  }
-
-  // handle hash
-  if (flags & FLAGS_HASH) {
-    if (!(flags & FLAGS_PRECISION) && len && ((len == prec) || (len == width))) {
-      len--;
-      if (len && (base == 16U)) {
-        len--;
-      }
-    }
-    if ((base == 16U) && !(flags & FLAGS_UPPERCASE) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
-      buf[len++] = 'x';
-    }
-    else if ((base == 16U) && (flags & FLAGS_UPPERCASE) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
-      buf[len++] = 'X';
-    }
-    else if ((base == 2U) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
-      buf[len++] = 'b';
-    }
-    if (len < PRINTF_NTOA_BUFFER_SIZE) {
-      buf[len++] = '0';
-    }
-  }
-
-  if (len < PRINTF_NTOA_BUFFER_SIZE) {
-    if (negative) {
-      buf[len++] = '-';
-    }
-    else if (flags & FLAGS_PLUS) {
-      buf[len++] = '+';  // ignore the space if the '+' exists
-    }
-    else if (flags & FLAGS_SPACE) {
-      buf[len++] = ' ';
-    }
-  }
-
-  // pad spaces up to given width
-  if (!(flags & FLAGS_LEFT) && !(flags & FLAGS_ZEROPAD)) {
-    for (size_t i = len; i < width; i++) {
-      out(' ', buffer, idx++, maxlen);
-    }
-  }
-
-  // reverse string
-  for (size_t i = 0U; i < len; i++) {
-    out(buf[len - i - 1U], buffer, idx++, maxlen);
-  }
-
-  // append pad spaces up to given width
-  if (flags & FLAGS_LEFT) {
-    while (idx - start_idx < width) {
-      out(' ', buffer, idx++, maxlen);
-    }
-  }
-
-  return idx;
-}
-
-
-// internal itoa for 'long' type
-static size_t _ntoa_long(out_fct_type out, char* buffer, size_t idx, size_t maxlen, unsigned long value, bool negative, unsigned long base, unsigned int prec, unsigned int width, unsigned int flags)
-{
-  char buf[PRINTF_NTOA_BUFFER_SIZE];
-  size_t len = 0U;
-
-  // no hash for 0 values
-  if (!value) {
-    flags &= ~FLAGS_HASH;
-  }
-
-  // write if precision != 0 and value is != 0
-  if (!(flags & FLAGS_PRECISION) || value) {
-    do {
-      const char digit = (char)(value % base);
-      buf[len++] = digit < 10 ? '0' + digit : (flags & FLAGS_UPPERCASE ? 'A' : 'a') + digit - 10;
-      value /= base;
-    } while (value && (len < PRINTF_NTOA_BUFFER_SIZE));
-  }
-
-  return _ntoa_format(out, buffer, idx, maxlen, buf, len, negative, (unsigned int)base, prec, width, flags);
-}
-
-
-// internal itoa for 'long long' type
-#if defined(PRINTF_SUPPORT_LONG_LONG)
-static size_t _ntoa_long_long(out_fct_type out, char* buffer, size_t idx, size_t maxlen, unsigned long long value, bool negative, unsigned long long base, unsigned int prec, unsigned int width, unsigned int flags)
-{
-  char buf[PRINTF_NTOA_BUFFER_SIZE];
-  size_t len = 0U;
-
-  // no hash for 0 values
-  if (!value) {
-    flags &= ~FLAGS_HASH;
-  }
-
-  // write if precision != 0 and value is != 0
-  if (!(flags & FLAGS_PRECISION) || value) {
-    do {
-      const char digit = (char)(value % base);
-      buf[len++] = digit < 10 ? '0' + digit : (flags & FLAGS_UPPERCASE ? 'A' : 'a') + digit - 10;
-      value /= base;
-    } while (value && (len < PRINTF_NTOA_BUFFER_SIZE));
-  }
-
-  return _ntoa_format(out, buffer, idx, maxlen, buf, len, negative, (unsigned int)base, prec, width, flags);
-}
-#endif  // PRINTF_SUPPORT_LONG_LONG
-
-
-#if defined(PRINTF_SUPPORT_FLOAT)
-static size_t _ftoa(out_fct_type out, char* buffer, size_t idx, size_t maxlen, double value, unsigned int prec, unsigned int width, unsigned int flags)
-{
-  const size_t start_idx = idx;
-
-  char buf[PRINTF_FTOA_BUFFER_SIZE];
-  size_t len  = 0U;
-  double diff = 0.0;
-
-  // if input is larger than thres_max, revert to exponential
-  const double thres_max = (double)0x7FFFFFFF;
-
-  // powers of 10
-  static const double pow10[] = { 1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000 };
-
-  // test for NaN
-  if (value != value) {
-    out('n', buffer, idx++, maxlen);
-    out('a', buffer, idx++, maxlen);
-    out('n', buffer, idx++, maxlen);
-    return idx;
-  }
-
-  // test for negative
-  bool negative = false;
-  if (value < 0) {
-    negative = true;
-    value = 0 - value;
-  }
-
-  // set default precision to 6, if not set explicitly
-  if (!(flags & FLAGS_PRECISION)) {
-    prec = 6U;
-  }
-  // limit precision to 9, cause a prec >= 10 can lead to overflow errors
-  while ((len < PRINTF_FTOA_BUFFER_SIZE) && (prec > 9U)) {
-    buf[len++] = '0';
-    prec--;
-  }
-
-  int whole = (int)value;
-  double tmp = (value - whole) * pow10[prec];
-  unsigned long frac = (unsigned long)tmp;
-  diff = tmp - frac;
-
-  if (diff > 0.5) {
-    ++frac;
-    // handle rollover, e.g. case 0.99 with prec 1 is 1.0
-    if (frac >= pow10[prec]) {
-      frac = 0;
-      ++whole;
-    }
-  }
-  else if (diff < 0.5) {
-  }
-  else if ((frac == 0U) || (frac & 1U)) {
-    // if halfway, round up if odd OR if last digit is 0
-    ++frac;
-  }
-
-  // TBD: for very large numbers switch back to native sprintf for exponentials. Anyone want to write code to replace this?
-  // Normal printf behavior is to print EVERY whole number digit which can be 100s of characters overflowing your buffers == bad
-  if (value > thres_max) {
-    return 0U;
-  }
-
-  if (prec == 0U) {
-    diff = value - (double)whole;
-    if ((!(diff < 0.5) || (diff > 0.5)) && (whole & 1)) {
-      // exactly 0.5 and ODD, then round up
-      // 1.5 -> 2, but 2.5 -> 2
-      ++whole;
-    }
-  }
-  else {
-    unsigned int count = prec;
-    // now do fractional part, as an unsigned number
-    while (len < PRINTF_FTOA_BUFFER_SIZE) {
-      --count;
-      buf[len++] = (char)(48U + (frac % 10U));
-      if (!(frac /= 10U)) {
-        break;
-      }
-    }
-    // add extra 0s
-    while ((len < PRINTF_FTOA_BUFFER_SIZE) && (count-- > 0U)) {
-      buf[len++] = '0';
-    }
-    if (len < PRINTF_FTOA_BUFFER_SIZE) {
-      // add decimal
-      buf[len++] = '.';
-    }
-  }
-
-  // do whole part, number is reversed
-  while (len < PRINTF_FTOA_BUFFER_SIZE) {
-    buf[len++] = (char)(48 + (whole % 10));
-    if (!(whole /= 10)) {
-      break;
-    }
-  }
-
-  // pad leading zeros
-  if (!(flags & FLAGS_LEFT) && (flags & FLAGS_ZEROPAD)) {
-    if (width && (negative || (flags & (FLAGS_PLUS | FLAGS_SPACE)))) {
-      width--;
-    }
-    while ((len < width) && (len < PRINTF_FTOA_BUFFER_SIZE)) {
-      buf[len++] = '0';
-    }
-  }
-
-  if (len < PRINTF_FTOA_BUFFER_SIZE) {
-    if (negative) {
-      buf[len++] = '-';
-    }
-    else if (flags & FLAGS_PLUS) {
-      buf[len++] = '+';  // ignore the space if the '+' exists
-    }
-    else if (flags & FLAGS_SPACE) {
-      buf[len++] = ' ';
-    }
-  }
-
-  // pad spaces up to given width
-  if (!(flags & FLAGS_LEFT) && !(flags & FLAGS_ZEROPAD)) {
-    for (size_t i = len; i < width; i++) {
-      out(' ', buffer, idx++, maxlen);
-    }
-  }
-
-  // reverse string
-  for (size_t i = 0U; i < len; i++) {
-    out(buf[len - i - 1U], buffer, idx++, maxlen);
-  }
-
-  // append pad spaces up to given width
-  if (flags & FLAGS_LEFT) {
-    while (idx - start_idx < width) {
-      out(' ', buffer, idx++, maxlen);
-    }
-  }
-
-  return idx;
-}
-#endif  // PRINTF_SUPPORT_FLOAT
-
-
-// internal vsnprintf
-static int _vsnprintf(out_fct_type out, char* buffer, const size_t maxlen, const char* format, va_list va)
-{
-  unsigned int flags, width, precision, n;
-  size_t idx = 0U;
-
-  if (!buffer) {
-    // use null output function
-    out = _out_null;
-  }
-
-  while (*format)
-  {
-    // format specifier?  %[flags][width][.precision][length]
-    if (*format != '%') {
-      // no
-      out(*format, buffer, idx++, maxlen);
-      format++;
-      continue;
-    }
-    else {
-      // yes, evaluate it
-      format++;
-    }
-
-    // evaluate flags
-    flags = 0U;
-    do {
-      switch (*format) {
-        case '0': flags |= FLAGS_ZEROPAD; format++; n = 1U; break;
-        case '-': flags |= FLAGS_LEFT;    format++; n = 1U; break;
-        case '+': flags |= FLAGS_PLUS;    format++; n = 1U; break;
-        case ' ': flags |= FLAGS_SPACE;   format++; n = 1U; break;
-        case '#': flags |= FLAGS_HASH;    format++; n = 1U; break;
-        default :                                   n = 0U; break;
-      }
-    } while (n);
-
-    // evaluate width field
-    width = 0U;
-    if (_is_digit(*format)) {
-      width = _atoi(&format);
-    }
-    else if (*format == '*') {
-      const int w = va_arg(va, int);
-      if (w < 0) {
-        flags |= FLAGS_LEFT;    // reverse padding
-        width = (unsigned int)-w;
-      }
-      else {
-        width = (unsigned int)w;
-      }
-      format++;
-    }
-
-    // evaluate precision field
-    precision = 0U;
-    if (*format == '.') {
-      flags |= FLAGS_PRECISION;
-      format++;
-      if (_is_digit(*format)) {
-        precision = _atoi(&format);
-      }
-      else if (*format == '*') {
-        const int prec = (int)va_arg(va, int);
-        precision = prec > 0 ? (unsigned int)prec : 0U;
-        format++;
-      }
-    }
-
-    // evaluate length field
-    switch (*format) {
-      case 'l' :
-        flags |= FLAGS_LONG;
-        format++;
-        if (*format == 'l') {
-          flags |= FLAGS_LONG_LONG;
-          format++;
-        }
-        break;
-      case 'h' :
-        flags |= FLAGS_SHORT;
-        format++;
-        if (*format == 'h') {
-          flags |= FLAGS_CHAR;
-          format++;
-        }
-        break;
-#if defined(PRINTF_SUPPORT_PTRDIFF_T)
-      case 't' :
-        flags |= (sizeof(ptrdiff_t) == sizeof(long) ? FLAGS_LONG : FLAGS_LONG_LONG);
-        format++;
-        break;
-#endif
-      case 'j' :
-        flags |= (sizeof(intmax_t) == sizeof(long) ? FLAGS_LONG : FLAGS_LONG_LONG);
-        format++;
-        break;
-      case 'z' :
-        flags |= (sizeof(size_t) == sizeof(long) ? FLAGS_LONG : FLAGS_LONG_LONG);
-        format++;
-        break;
-      default :
-        break;
-    }
-
-    // evaluate specifier
-    switch (*format) {
-      case 'd' :
-      case 'i' :
-      case 'u' :
-      case 'x' :
-      case 'X' :
-      case 'o' :
-      case 'b' : {
-        // set the base
-        unsigned int base;
-        if (*format == 'x' || *format == 'X') {
-          base = 16U;
-        }
-        else if (*format == 'o') {
-          base =  8U;
-        }
-        else if (*format == 'b') {
-          base =  2U;
-        }
-        else {
-          base = 10U;
-          flags &= ~FLAGS_HASH;   // no hash for dec format
-        }
-        // uppercase
-        if (*format == 'X') {
-          flags |= FLAGS_UPPERCASE;
-        }
-
-        // no plus or space flag for u, x, X, o, b
-        if ((*format != 'i') && (*format != 'd')) {
-          flags &= ~(FLAGS_PLUS | FLAGS_SPACE);
-        }
-
-        // ignore '0' flag when precision is given
-        if (flags & FLAGS_PRECISION) {
-          flags &= ~FLAGS_ZEROPAD;
-        }
-
-        // convert the integer
-        if ((*format == 'i') || (*format == 'd')) {
-          // signed
-          if (flags & FLAGS_LONG_LONG) {
-#if defined(PRINTF_SUPPORT_LONG_LONG)
-            const long long value = va_arg(va, long long);
-            idx = _ntoa_long_long(out, buffer, idx, maxlen, (unsigned long long)(value > 0 ? value : 0 - value), value < 0, base, precision, width, flags);
-#endif
-          }
-          else if (flags & FLAGS_LONG) {
-            const long value = va_arg(va, long);
-            idx = _ntoa_long(out, buffer, idx, maxlen, (unsigned long)(value > 0 ? value : 0 - value), value < 0, base, precision, width, flags);
-          }
-          else {
-            const int value = (flags & FLAGS_CHAR) ? (char)va_arg(va, int) : (flags & FLAGS_SHORT) ? (short int)va_arg(va, int) : va_arg(va, int);
-            idx = _ntoa_long(out, buffer, idx, maxlen, (unsigned int)(value > 0 ? value : 0 - value), value < 0, base, precision, width, flags);
-          }
-        }
-        else {
-          // unsigned
-          if (flags & FLAGS_LONG_LONG) {
-#if defined(PRINTF_SUPPORT_LONG_LONG)
-            idx = _ntoa_long_long(out, buffer, idx, maxlen, va_arg(va, unsigned long long), false, base, precision, width, flags);
-#endif
-          }
-          else if (flags & FLAGS_LONG) {
-            idx = _ntoa_long(out, buffer, idx, maxlen, va_arg(va, unsigned long), false, base, precision, width, flags);
-          }
-          else {
-            const unsigned int value = (flags & FLAGS_CHAR) ? (unsigned char)va_arg(va, unsigned int) : (flags & FLAGS_SHORT) ? (unsigned short int)va_arg(va, unsigned int) : va_arg(va, unsigned int);
-            idx = _ntoa_long(out, buffer, idx, maxlen, value, false, base, precision, width, flags);
-          }
-        }
-        format++;
-        break;
-      }
-#if defined(PRINTF_SUPPORT_FLOAT)
-      case 'f' :
-      case 'F' :
-        idx = _ftoa(out, buffer, idx, maxlen, va_arg(va, double), precision, width, flags);
-        format++;
-        break;
-#endif  // PRINTF_SUPPORT_FLOAT
-      case 'c' : {
-        unsigned int l = 1U;
-        // pre padding
-        if (!(flags & FLAGS_LEFT)) {
-          while (l++ < width) {
-            out(' ', buffer, idx++, maxlen);
-          }
-        }
-        // char output
-        out((char)va_arg(va, int), buffer, idx++, maxlen);
-        // post padding
-        if (flags & FLAGS_LEFT) {
-          while (l++ < width) {
-            out(' ', buffer, idx++, maxlen);
-          }
-        }
-        format++;
-        break;
-      }
-
-      case 's' : {
-        const char* p = va_arg(va, char*);
-        unsigned int l = _strnlen_s(p, precision ? precision : (size_t)-1);
-        // pre padding
-        if (flags & FLAGS_PRECISION) {
-          l = (l < precision ? l : precision);
-        }
-        if (!(flags & FLAGS_LEFT)) {
-          while (l++ < width) {
-            out(' ', buffer, idx++, maxlen);
-          }
-        }
-        // string output
-        while ((*p != 0) && (!(flags & FLAGS_PRECISION) || precision--)) {
-          out(*(p++), buffer, idx++, maxlen);
-        }
-        // post padding
-        if (flags & FLAGS_LEFT) {
-          while (l++ < width) {
-            out(' ', buffer, idx++, maxlen);
-          }
-        }
-        format++;
-        break;
-      }
-
-      case 'p' : {
-        width = sizeof(void*) * 2U;
-        flags |= FLAGS_ZEROPAD | FLAGS_UPPERCASE;
-#if defined(PRINTF_SUPPORT_LONG_LONG)
-        const bool is_ll = sizeof(uintptr_t) == sizeof(long long);
-        if (is_ll) {
-          idx = _ntoa_long_long(out, buffer, idx, maxlen, (uintptr_t)va_arg(va, void*), false, 16U, precision, width, flags);
-        }
-        else {
-#endif
-          idx = _ntoa_long(out, buffer, idx, maxlen, (unsigned long)((uintptr_t)va_arg(va, void*)), false, 16U, precision, width, flags);
-#if defined(PRINTF_SUPPORT_LONG_LONG)
-        }
-#endif
-        format++;
-        break;
-      }
-
-      case '%' :
-        out('%', buffer, idx++, maxlen);
-        format++;
-        break;
-
-      default :
-        out(*format, buffer, idx++, maxlen);
-        format++;
-        break;
-    }
-  }
-
-  // termination
-  out((char)0, buffer, idx < maxlen ? idx : maxlen - 1U, maxlen);
-
-  // return written chars without terminating \0
-  return (int)idx;
-}
-
-
-///////////////////////////////////////////////////////////////////////////////
-
-#ifdef PRINTF_PUTCHAR_FUNC
-int printf_(const char* format, ...)
-{
-  va_list va;
-  va_start(va, format);
-  char buffer[1];
-  const int ret = _vsnprintf(_out_char, buffer, (size_t)-1, format, va);
-  va_end(va);
-  return ret;
-}
-#endif
-
-int sprintf_(char* buffer, const char* format, ...)
-{
-  va_list va;
-  va_start(va, format);
-  const int ret = _vsnprintf(_out_buffer, buffer, (size_t)-1, format, va);
-  va_end(va);
-  return ret;
-}
-
-
-int snprintf_(char* buffer, size_t count, const char* format, ...)
-{
-  va_list va;
-  va_start(va, format);
-  const int ret = _vsnprintf(_out_buffer, buffer, count, format, va);
-  va_end(va);
-  return ret;
-}
-
-
-int vsnprintf_(char* buffer, size_t count, const char* format, va_list va)
-{
-  return _vsnprintf(_out_buffer, buffer, count, format, va);
-}
-
-
-int fctprintf(void (*out)(char character, void* arg), void* arg, const char* format, ...)
-{
-  va_list va;
-  va_start(va, format);
-  const out_fct_wrap_type out_fct_wrap = { out, arg };
-  const int ret = _vsnprintf(_out_fct, (char*)(uintptr_t)&out_fct_wrap, (size_t)-1, format, va);
-  va_end(va);
-  return ret;
-}