Added `nanoprintf.h` header only library to implement `::to_string` functions.

 * `eastl::to_string` does not work for now

Signed-off-by: Toni Uhlig <matzeton@googlemail.com>

9 files changed, 1282 insertions, 0 deletions

diff --git a/CRT/eastl_compat.cpp b/CRT/eastl_compat.cpp
new file mode 100644
index 0000000..43068b3
--- /dev/null
+++ b/CRT/eastl_compat.cpp
@@ -0,0 +1,120 @@
+#include "eastl_compat.hpp"
+
+#define NANOPRINTF_VISIBILITY_STATIC 1
+#define NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS 1
+#define NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS 1
+#define NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS 1
+#define NANOPRINTF_USE_LARGE_FORMAT_SPECIFIERS 1
+#define NANOPRINTF_USE_BINARY_FORMAT_SPECIFIERS 0
+#define NANOPRINTF_USE_WRITEBACK_FORMAT_SPECIFIERS 0
+#define NANOPRINTF_IMPLEMENTATION 1
+#include "nanoprintf.h"
+
+/*
+ * eastl::to_string(...) does not work yet event if with a provided Vsnprintf/Vsnprintf8
+ * The issue seems to be caused by a broken va_list/va_copy.
+ */
+
+eastl::string to_string(int value)
+{
+    int nbytes = npf_snprintf(nullptr, 0, "%d", value);
+    if (nbytes > 0)
+    {
+        char result[nbytes + 1] = {};
+        npf_snprintf(result, nbytes, "%d", value);
+        return result;
+    }
+    else
+        return "";
+}
+
+eastl::string to_string(long value)
+{
+    int nbytes = npf_snprintf(nullptr, 0, "%ld", value);
+    if (nbytes > 0)
+    {
+        char result[nbytes + 1] = {};
+        npf_snprintf(result, nbytes, "%ld", value);
+        return result;
+    }
+    else
+        return "";
+}
+
+eastl::string to_string(long long value)
+{
+    int nbytes = npf_snprintf(nullptr, 0, "%lld", value);
+    if (nbytes > 0)
+    {
+        char result[nbytes + 1] = {};
+        npf_snprintf(result, nbytes, "%lld", value);
+        return result;
+    }
+    else
+        return "";
+}
+
+eastl::string to_string(unsigned int value)
+{
+    int nbytes = npf_snprintf(nullptr, 0, "%u", value);
+    if (nbytes > 0)
+    {
+        char result[nbytes + 1] = {};
+        npf_snprintf(result, nbytes, "%u", value);
+        return result;
+    }
+    else
+        return "";
+}
+
+eastl::string to_string(unsigned long int value)
+{
+    int nbytes = npf_snprintf(nullptr, 0, "%lu", value);
+    if (nbytes > 0)
+    {
+        char result[nbytes + 1] = {};
+        npf_snprintf(result, nbytes, "%lu", value);
+        return result;
+    }
+    else
+        return "";
+}
+
+eastl::string to_string(unsigned long long int value)
+{
+    int nbytes = npf_snprintf(nullptr, 0, "%llu", value);
+    if (nbytes > 0)
+    {
+        char result[nbytes + 1] = {};
+        npf_snprintf(result, nbytes, "%llu", value);
+        return result;
+    }
+    else
+        return "";
+}
+
+eastl::string to_string(float value)
+{
+    int nbytes = npf_snprintf(nullptr, 0, "%f", value);
+    if (nbytes > 0)
+    {
+        char result[nbytes + 1] = {};
+        npf_snprintf(result, nbytes, "%f", value);
+        return result;
+    }
+    else
+        return "";
+}
+
+eastl::string to_string(double value)
+{
+    int nbytes = npf_snprintf(nullptr, 0, "%lf", value);
+    if (nbytes > 0)
+    {
+        char result[nbytes + 1] = {};
+        npf_snprintf(result, nbytes, "%lf", value);
+        return result;
+    }
+    else
+        return "";
+}
diff --git a/CRT/eastl_compat.hpp b/CRT/eastl_compat.hpp
new file mode 100644
index 0000000..773f7fa
--- /dev/null
+++ b/CRT/eastl_compat.hpp
@@ -0,0 +1,15 @@
+#ifndef EASTL_COMPAT
+#define EASTL_COMPAT 1
+
+#include <EASTL/string.h>
+
+eastl::string to_string(int value);
+eastl::string to_string(long value);
+eastl::string to_string(long long value);
+eastl::string to_string(unsigned int value);
+eastl::string to_string(unsigned long int value);
+eastl::string to_string(unsigned long long int value);
+eastl::string to_string(float value);
+eastl::string to_string(double value);
+
+#endif
diff --git a/CRT/kcrt.c b/CRT/kcrt.c
index fd57b29..7bc2637 100644
--- a/CRT/kcrt.c
+++ b/CRT/kcrt.c
@@ -304,3 +304,9 @@ void * __cdecl _AddressOfReturnAddress(void)
 {
     return __builtin_extract_return_addr(__builtin_return_address(0));
 }
+
+char __cdecl _putchar(char c)
+{
+    DbgPrint("%c", c);
+    return c;
+}
diff --git a/CRT/nanoprintf.h b/CRT/nanoprintf.h
new file mode 100644
index 0000000..290ddfe
--- /dev/null
+++ b/CRT/nanoprintf.h
@@ -0,0 +1,1104 @@
+/* nanoprintf: a tiny embeddable printf replacement written in C.
+   https://github.com/charlesnicholson/nanoprintf
+   charles.nicholson+nanoprintf@gmail.com
+   dual-licensed under 0bsd and unlicense, take your pick. see eof for details. */
+
+#ifndef NANOPRINTF_H_INCLUDED
+#define NANOPRINTF_H_INCLUDED
+
+#include <stdarg.h>
+#include <stddef.h>
+
+// Define this to fully sandbox nanoprintf inside of a translation unit.
+#ifdef NANOPRINTF_VISIBILITY_STATIC
+  #define NPF_VISIBILITY static
+#else
+  #define NPF_VISIBILITY extern
+#endif
+
+#if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
+  #define NPF_PRINTF_ATTR(FORMAT_INDEX, VARGS_INDEX) \
+    __attribute__((format(printf, FORMAT_INDEX, VARGS_INDEX)))
+#else
+  #define NPF_PRINTF_ATTR(FORMAT_INDEX, VARGS_INDEX)
+#endif
+
+// Public API
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// The npf_ functions all return the number of bytes required to express the
+// fully-formatted string, not including the null terminator character.
+// The npf_ functions do not return negative values, since the lack of 'l' length
+// modifier support makes encoding errors impossible.
+
+NPF_VISIBILITY int npf_snprintf(
+  char *buffer, size_t bufsz, const char *format, ...) NPF_PRINTF_ATTR(3, 4);
+
+NPF_VISIBILITY int npf_vsnprintf(
+  char *buffer, size_t bufsz, char const *format, va_list vlist) NPF_PRINTF_ATTR(3, 0);
+
+typedef void (*npf_putc)(int c, void *ctx);
+NPF_VISIBILITY int npf_pprintf(
+  npf_putc pc, void *pc_ctx, char const *format, ...) NPF_PRINTF_ATTR(3, 4);
+
+NPF_VISIBILITY int npf_vpprintf(
+  npf_putc pc, void *pc_ctx, char const *format, va_list vlist) NPF_PRINTF_ATTR(3, 0);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // NANOPRINTF_H_INCLUDED
+
+/* The implementation of nanoprintf begins here, to be compiled only if
+   NANOPRINTF_IMPLEMENTATION is defined. In a multi-file library what follows would
+   be nanoprintf.c. */
+
+#ifdef NANOPRINTF_IMPLEMENTATION
+
+#ifndef NANOPRINTF_IMPLEMENTATION_INCLUDED
+#define NANOPRINTF_IMPLEMENTATION_INCLUDED
+
+#include <inttypes.h>
+#include <stdint.h>
+
+// Pick reasonable defaults if nothing's been configured.
+#if !defined(NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS) && \
+    !defined(NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS) && \
+    !defined(NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS) && \
+    !defined(NANOPRINTF_USE_LARGE_FORMAT_SPECIFIERS) && \
+    !defined(NANOPRINTF_USE_BINARY_FORMAT_SPECIFIERS) && \
+    !defined(NANOPRINTF_USE_WRITEBACK_FORMAT_SPECIFIERS)
+  #define NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS 1
+  #define NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS 1
+  #define NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS 1
+  #define NANOPRINTF_USE_LARGE_FORMAT_SPECIFIERS 0
+  #define NANOPRINTF_USE_BINARY_FORMAT_SPECIFIERS 0
+  #define NANOPRINTF_USE_WRITEBACK_FORMAT_SPECIFIERS 0
+#endif
+
+// If anything's been configured, everything must be configured.
+#ifndef NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS
+  #error NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS must be #defined to 0 or 1
+#endif
+#ifndef NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS
+  #error NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS must be #defined to 0 or 1
+#endif
+#ifndef NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS
+  #error NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS must be #defined to 0 or 1
+#endif
+#ifndef NANOPRINTF_USE_LARGE_FORMAT_SPECIFIERS
+  #error NANOPRINTF_USE_LARGE_FORMAT_SPECIFIERS must be #defined to 0 or 1
+#endif
+#ifndef NANOPRINTF_USE_BINARY_FORMAT_SPECIFIERS
+  #error NANOPRINTF_USE_BINARY_FORMAT_SPECIFIERS must be #defined to 0 or 1
+#endif
+#ifndef NANOPRINTF_USE_WRITEBACK_FORMAT_SPECIFIERS
+  #error NANOPRINTF_USE_WRITEBACK_FORMAT_SPECIFIERS must be #defined to 0 or 1
+#endif
+
+// Ensure flags are compatible.
+#if (NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1) && \
+    (NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 0)
+  #error Precision format specifiers must be enabled if float support is enabled.
+#endif
+
+#if defined(NANOPRINTF_SNPRINTF_SAFE_EMPTY_STRING_ON_OVERFLOW) && \
+    defined(NANOPRINTF_SNPRINTF_SAFE_TRIM_STRING_ON_OVERFLOW)
+  #error snprintf safety flags are mutually exclusive.
+#endif
+
+// intmax_t / uintmax_t require stdint from c99 / c++11
+#if NANOPRINTF_USE_LARGE_FORMAT_SPECIFIERS == 1
+  #ifndef _MSC_VER
+    #ifdef __cplusplus
+      #if __cplusplus < 201103L
+        #error large format specifier support requires C++11 or later.
+      #endif
+    #else
+      #if __STDC_VERSION__ < 199409L
+        #error nanoprintf requires C99 or later.
+      #endif
+    #endif
+  #endif
+#endif
+
+// Figure out if we can disable warnings with pragmas.
+#ifdef __clang__
+  #define NANOPRINTF_CLANG 1
+  #define NANOPRINTF_GCC_PAST_4_6 0
+#else
+  #define NANOPRINTF_CLANG 0
+  #if defined(__GNUC__) && ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 6)))
+    #define NANOPRINTF_GCC_PAST_4_6 1
+  #else
+    #define NANOPRINTF_GCC_PAST_4_6 0
+  #endif
+#endif
+
+#if NANOPRINTF_CLANG || NANOPRINTF_GCC_PAST_4_6
+  #define NANOPRINTF_HAVE_GCC_WARNING_PRAGMAS 1
+#else
+  #define NANOPRINTF_HAVE_GCC_WARNING_PRAGMAS 0
+#endif
+
+#if NANOPRINTF_HAVE_GCC_WARNING_PRAGMAS
+  #pragma GCC diagnostic push
+  #pragma GCC diagnostic ignored "-Wunused-function"
+  #pragma GCC diagnostic ignored "-Wimplicit-fallthrough"
+  #ifdef __cplusplus
+    #pragma GCC diagnostic ignored "-Wold-style-cast"
+  #endif
+  #pragma GCC diagnostic ignored "-Wpadded"
+  #pragma GCC diagnostic ignored "-Wfloat-equal"
+  #if NANOPRINTF_CLANG
+    #pragma GCC diagnostic ignored "-Wc++98-compat-pedantic"
+    #pragma GCC diagnostic ignored "-Wcovered-switch-default"
+    #pragma GCC diagnostic ignored "-Wdeclaration-after-statement"
+  #elif NANOPRINTF_GCC_PAST_4_6
+    #pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+  #endif
+#endif
+
+#ifdef _MSC_VER
+  #pragma warning(push)
+  #pragma warning(disable:4514) // unreferenced inline function removed
+  #pragma warning(disable:4505) // unreferenced function removed
+  #pragma warning(disable:4701) // possibly uninitialized
+  #pragma warning(disable:4706) // assignment in conditional
+  #pragma warning(disable:4710) // not inlined
+  #pragma warning(disable:4711) // selected for inline
+  #pragma warning(disable:4820) // padding after data member
+  #pragma warning(disable:5039) // extern "C" throw
+  #pragma warning(disable:5045) // spectre mitigation
+  #pragma warning(disable:5262) // implicit switch fall-through
+#endif
+
+#if (NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS == 1) || \
+    (NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1)
+typedef enum {
+  NPF_FMT_SPEC_OPT_NONE,
+  NPF_FMT_SPEC_OPT_LITERAL,
+  NPF_FMT_SPEC_OPT_STAR,
+} npf_fmt_spec_opt_t;
+#endif
+
+typedef enum {
+  NPF_FMT_SPEC_LEN_MOD_NONE,
+  NPF_FMT_SPEC_LEN_MOD_SHORT,       // 'h'
+  NPF_FMT_SPEC_LEN_MOD_LONG_DOUBLE, // 'L'
+  NPF_FMT_SPEC_LEN_MOD_CHAR,        // 'hh'
+  NPF_FMT_SPEC_LEN_MOD_LONG,        // 'l'
+#if NANOPRINTF_USE_LARGE_FORMAT_SPECIFIERS == 1
+  NPF_FMT_SPEC_LEN_MOD_LARGE_LONG_LONG, // 'll'
+  NPF_FMT_SPEC_LEN_MOD_LARGE_INTMAX,    // 'j'
+  NPF_FMT_SPEC_LEN_MOD_LARGE_SIZET,     // 'z'
+  NPF_FMT_SPEC_LEN_MOD_LARGE_PTRDIFFT,  // 't'
+#endif
+} npf_format_spec_length_modifier_t;
+
+typedef enum {
+  NPF_FMT_SPEC_CONV_PERCENT,      // '%'
+  NPF_FMT_SPEC_CONV_CHAR,         // 'c'
+  NPF_FMT_SPEC_CONV_STRING,       // 's'
+  NPF_FMT_SPEC_CONV_SIGNED_INT,   // 'i', 'd'
+#if NANOPRINTF_USE_BINARY_FORMAT_SPECIFIERS == 1
+  NPF_FMT_SPEC_CONV_BINARY,       // 'b'
+#endif
+  NPF_FMT_SPEC_CONV_OCTAL,        // 'o'
+  NPF_FMT_SPEC_CONV_HEX_INT,      // 'x', 'X'
+  NPF_FMT_SPEC_CONV_UNSIGNED_INT, // 'u'
+  NPF_FMT_SPEC_CONV_POINTER,      // 'p'
+#if NANOPRINTF_USE_WRITEBACK_FORMAT_SPECIFIERS == 1
+  NPF_FMT_SPEC_CONV_WRITEBACK,    // 'n'
+#endif
+#if NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1
+  NPF_FMT_SPEC_CONV_FLOAT_DEC,      // 'f', 'F'
+  NPF_FMT_SPEC_CONV_FLOAT_SCI,      // 'e', 'E'
+  NPF_FMT_SPEC_CONV_FLOAT_SHORTEST, // 'g', 'G'
+  NPF_FMT_SPEC_CONV_FLOAT_HEX,      // 'a', 'A'
+#endif
+} npf_format_spec_conversion_t;
+
+typedef struct npf_format_spec {
+  char prepend;          // ' ' or '+'
+  char alt_form;         // '#'
+
+#if NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS == 1
+  npf_fmt_spec_opt_t field_width_opt;
+  int field_width;
+  char left_justified;   // '-'
+  char leading_zero_pad; // '0'
+#endif
+
+#if NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1
+  npf_fmt_spec_opt_t prec_opt;
+  int prec;
+#endif
+
+  npf_format_spec_length_modifier_t length_modifier;
+  npf_format_spec_conversion_t conv_spec;
+  char case_adjust;
+} npf_format_spec_t;
+
+#if NANOPRINTF_USE_LARGE_FORMAT_SPECIFIERS == 0
+  typedef long npf_int_t;
+  typedef unsigned long npf_uint_t;
+#else
+  typedef intmax_t npf_int_t;
+  typedef uintmax_t npf_uint_t;
+#endif
+
+typedef struct npf_bufputc_ctx {
+  char *dst;
+  size_t len;
+  size_t cur;
+} npf_bufputc_ctx_t;
+
+static int npf_parse_format_spec(char const *format, npf_format_spec_t *out_spec);
+static void npf_bufputc(int c, void *ctx);
+static void npf_bufputc_nop(int c, void *ctx);
+static int npf_itoa_rev(char *buf, npf_int_t i);
+static int npf_utoa_rev(char *buf, npf_uint_t i, unsigned base, unsigned case_adjust);
+
+#if NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1
+static int npf_fsplit_abs(float f,
+                          uint64_t *out_int_part,
+                          uint64_t *out_frac_part,
+                          int *out_frac_base10_neg_e);
+static int npf_ftoa_rev(char *buf, float f, char case_adj, int *out_frac_chars);
+#endif
+
+#if NANOPRINTF_USE_BINARY_FORMAT_SPECIFIERS == 1
+static int npf_bin_len(npf_uint_t i);
+#endif
+
+#if NANOPRINTF_USE_LARGE_FORMAT_SPECIFIERS == 1
+  #ifdef _MSC_VER
+    #include <BaseTsd.h>
+    typedef SSIZE_T ssize_t;
+  #else
+    #include <sys/types.h>
+  #endif
+#endif
+
+#ifdef _MSC_VER
+  #include <intrin.h>
+#endif
+
+static int npf_max(int x, int y) { return (x > y) ? x : y; }
+
+int npf_parse_format_spec(char const *format, npf_format_spec_t *out_spec) {
+  char const *cur = format;
+
+#if NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS == 1
+  out_spec->left_justified = 0;
+  out_spec->leading_zero_pad = 0;
+#endif
+  out_spec->case_adjust = 'a'-'A'; // lowercase
+  out_spec->prepend = 0;
+  out_spec->alt_form = 0;
+
+  while (*++cur) { // cur points at the leading '%' character
+    switch (*cur) { // Optional flags
+#if NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS == 1
+      case '-': out_spec->left_justified = '-'; out_spec->leading_zero_pad = 0; continue;
+      case '0': out_spec->leading_zero_pad = !out_spec->left_justified; continue;
+#endif
+      case '+': out_spec->prepend = '+'; continue;
+      case ' ': if (out_spec->prepend == 0) { out_spec->prepend = ' '; } continue;
+      case '#': out_spec->alt_form = '#'; continue;
+      default: break;
+    }
+    break;
+  }
+
+#if NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS == 1
+  out_spec->field_width_opt = NPF_FMT_SPEC_OPT_NONE;
+  if (*cur == '*') {
+    out_spec->field_width_opt = NPF_FMT_SPEC_OPT_STAR;
+    ++cur;
+  } else {
+    out_spec->field_width = 0;
+    while ((*cur >= '0') && (*cur <= '9')) {
+      out_spec->field_width_opt = NPF_FMT_SPEC_OPT_LITERAL;
+      out_spec->field_width = (out_spec->field_width * 10) + (*cur++ - '0');
+    }
+  }
+#endif
+
+#if NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1
+  out_spec->prec = 0;
+  out_spec->prec_opt = NPF_FMT_SPEC_OPT_NONE;
+  if (*cur == '.') {
+    ++cur;
+    if (*cur == '*') {
+      out_spec->prec_opt = NPF_FMT_SPEC_OPT_STAR;
+      ++cur;
+    } else {
+      if (*cur == '-') {
+        ++cur;
+        out_spec->prec_opt = NPF_FMT_SPEC_OPT_NONE;
+      } else {
+        out_spec->prec_opt = NPF_FMT_SPEC_OPT_LITERAL;
+      }
+      while ((*cur >= '0') && (*cur <= '9')) {
+        out_spec->prec = (out_spec->prec * 10) + (*cur++ - '0');
+      }
+    }
+  }
+#endif
+
+  int tmp_conv = -1;
+  out_spec->length_modifier = NPF_FMT_SPEC_LEN_MOD_NONE;
+  switch (*cur++) { // Length modifier
+    case 'h':
+      out_spec->length_modifier = NPF_FMT_SPEC_LEN_MOD_SHORT;
+      if (*cur == 'h') {
+        out_spec->length_modifier = NPF_FMT_SPEC_LEN_MOD_CHAR;
+        ++cur;
+      }
+      break;
+    case 'l':
+      out_spec->length_modifier = NPF_FMT_SPEC_LEN_MOD_LONG;
+#if NANOPRINTF_USE_LARGE_FORMAT_SPECIFIERS == 1
+      if (*cur == 'l') {
+        out_spec->length_modifier = NPF_FMT_SPEC_LEN_MOD_LARGE_LONG_LONG;
+        ++cur;
+      }
+#endif
+      break;
+#if NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1
+    case 'L': out_spec->length_modifier = NPF_FMT_SPEC_LEN_MOD_LONG_DOUBLE; break;
+#endif
+#if NANOPRINTF_USE_LARGE_FORMAT_SPECIFIERS == 1
+    case 'j': out_spec->length_modifier = NPF_FMT_SPEC_LEN_MOD_LARGE_INTMAX; break;
+    case 'z': out_spec->length_modifier = NPF_FMT_SPEC_LEN_MOD_LARGE_SIZET; break;
+    case 't': out_spec->length_modifier = NPF_FMT_SPEC_LEN_MOD_LARGE_PTRDIFFT; break;
+#endif
+    default: --cur; break;
+  }
+
+  switch (*cur++) { // Conversion specifier
+    case '%': out_spec->conv_spec = NPF_FMT_SPEC_CONV_PERCENT;
+#if NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1
+      out_spec->prec_opt = NPF_FMT_SPEC_OPT_NONE;
+#endif
+      break;
+
+    case 'c': out_spec->conv_spec = NPF_FMT_SPEC_CONV_CHAR;
+#if NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1
+      out_spec->prec_opt = NPF_FMT_SPEC_OPT_NONE;
+#endif
+      break;
+
+    case 's': out_spec->conv_spec = NPF_FMT_SPEC_CONV_STRING;
+#if NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS == 1
+      out_spec->leading_zero_pad = 0;
+#endif
+      break;
+
+    case 'i':
+    case 'd': tmp_conv = NPF_FMT_SPEC_CONV_SIGNED_INT;
+    case 'o': if (tmp_conv == -1) { tmp_conv = NPF_FMT_SPEC_CONV_OCTAL; }
+    case 'u': if (tmp_conv == -1) { tmp_conv = NPF_FMT_SPEC_CONV_UNSIGNED_INT; }
+    case 'X': if (tmp_conv == -1) { out_spec->case_adjust = 0; }
+    case 'x': if (tmp_conv == -1) { tmp_conv = NPF_FMT_SPEC_CONV_HEX_INT; }
+      out_spec->conv_spec = (npf_format_spec_conversion_t)tmp_conv;
+#if (NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS == 1) && \
+    (NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1)
+      if (out_spec->prec_opt != NPF_FMT_SPEC_OPT_NONE) { out_spec->leading_zero_pad = 0; }
+#endif
+      break;
+
+#if NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1
+    case 'F': out_spec->case_adjust = 0;
+    case 'f':
+      out_spec->conv_spec = NPF_FMT_SPEC_CONV_FLOAT_DEC;
+      if (out_spec->prec_opt == NPF_FMT_SPEC_OPT_NONE) { out_spec->prec = 6; }
+      break;
+
+    case 'E': out_spec->case_adjust = 0;
+    case 'e':
+      out_spec->conv_spec = NPF_FMT_SPEC_CONV_FLOAT_SCI;
+      if (out_spec->prec_opt == NPF_FMT_SPEC_OPT_NONE) { out_spec->prec = 6; }
+      break;
+
+    case 'G': out_spec->case_adjust = 0;
+    case 'g':
+      out_spec->conv_spec = NPF_FMT_SPEC_CONV_FLOAT_SHORTEST;
+      if (out_spec->prec_opt == NPF_FMT_SPEC_OPT_NONE) { out_spec->prec = 6; }
+      break;
+
+    case 'A': out_spec->case_adjust = 0;
+    case 'a':
+      out_spec->conv_spec = NPF_FMT_SPEC_CONV_FLOAT_HEX;
+      if (out_spec->prec_opt == NPF_FMT_SPEC_OPT_NONE) { out_spec->prec = 6; }
+      break;
+#endif
+
+#if NANOPRINTF_USE_WRITEBACK_FORMAT_SPECIFIERS == 1
+    case 'n':
+      // todo: reject string if flags or width or precision exist
+      out_spec->conv_spec = NPF_FMT_SPEC_CONV_WRITEBACK;
+#if NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1
+      out_spec->prec_opt = NPF_FMT_SPEC_OPT_NONE;
+#endif
+      break;
+#endif
+
+    case 'p':
+      out_spec->conv_spec = NPF_FMT_SPEC_CONV_POINTER;
+#if NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1
+      out_spec->prec_opt = NPF_FMT_SPEC_OPT_NONE;
+#endif
+      break;
+
+#if NANOPRINTF_USE_BINARY_FORMAT_SPECIFIERS == 1
+    case 'B':
+      out_spec->case_adjust = 0;
+    case 'b':
+      out_spec->conv_spec = NPF_FMT_SPEC_CONV_BINARY;
+      break;
+#endif
+
+    default: return 0;
+  }
+
+  return (int)(cur - format);
+}
+
+int npf_itoa_rev(char *buf, npf_int_t i) {
+  int n = 0;
+  int const sign = (i >= 0) ? 1 : -1;
+  do { *buf++ = (char)('0' + (sign * (i % 10))); i /= 10; ++n; } while (i);
+  return n;
+}
+
+int npf_utoa_rev(char *buf, npf_uint_t i, unsigned base, unsigned case_adj) {
+  int n = 0;
+  do {
+    unsigned const d = (unsigned)(i % base);
+    *buf++ = (char)((d < 10) ? ('0' + d) : ('A' + case_adj + (d - 10)));
+    i /= base;
+    ++n;
+  } while (i);
+  return n;
+}
+
+#if NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1
+enum {
+  NPF_MANTISSA_BITS = 23,
+  NPF_EXPONENT_BITS = 8,
+  NPF_EXPONENT_BIAS = 127,
+  NPF_FRACTION_BIN_DIGITS = 64,
+  NPF_MAX_FRACTION_DEC_DIGITS = 8
+};
+
+int npf_fsplit_abs(float f, uint64_t *out_int_part, uint64_t *out_frac_part,
+                   int *out_frac_base10_neg_exp) {
+  /* conversion algorithm by Wojciech Muła (zdjęcia@garnek.pl)
+     http://0x80.pl/notesen/2015-12-29-float-to-string.html
+     grisu2 (https://bit.ly/2JgMggX) and ryu (https://bit.ly/2RLXSg0)
+     are fast + precise + round, but require large lookup tables. */
+
+  uint32_t f_bits; { // union-cast is UB, let compiler optimize byte-copy loop.
+    char const *src = (char const *)&f;
+    char *dst = (char *)&f_bits;
+    for (unsigned i = 0; i < sizeof(f_bits); ++i) { dst[i] = src[i]; }
+  }
+
+  int const exponent =
+    ((int)((f_bits >> NPF_MANTISSA_BITS) & ((1u << NPF_EXPONENT_BITS) - 1u)) -
+      NPF_EXPONENT_BIAS) - NPF_MANTISSA_BITS;
+
+  if (exponent >= (64 - NPF_MANTISSA_BITS)) { return 0; } // value is out of range
+
+  uint32_t const implicit_one = ((uint32_t)1) << NPF_MANTISSA_BITS;
+  uint32_t const mantissa = f_bits & (implicit_one - 1);
+  uint32_t const mantissa_norm = mantissa | implicit_one;
+
+  if (exponent > 0) {
+    *out_int_part = (uint64_t)mantissa_norm << exponent;
+  } else if (exponent < 0) {
+    if (-exponent > NPF_MANTISSA_BITS) {
+      *out_int_part = 0;
+    } else {
+      *out_int_part = mantissa_norm >> -exponent;
+    }
+  } else {
+    *out_int_part = mantissa_norm;
+  }
+
+  uint64_t frac; {
+    int const shift = NPF_FRACTION_BIN_DIGITS + exponent - 4;
+    if ((shift >= (NPF_FRACTION_BIN_DIGITS - 4)) || (shift < 0)) {
+      frac = 0;
+    } else {
+      frac = ((uint64_t)mantissa_norm) << shift;
+    }
+    // multiply off the leading one's digit
+    frac &= 0x0fffffffffffffffllu;
+    frac *= 10;
+  }
+
+  { // Count the number of 0s at the beginning of the fractional part.
+    int frac_base10_neg_exp = 0;
+    while (frac && ((frac >> (NPF_FRACTION_BIN_DIGITS - 4))) == 0) {
+      ++frac_base10_neg_exp;
+      frac &= 0x0fffffffffffffffllu;
+      frac *= 10;
+    }
+    *out_frac_base10_neg_exp = frac_base10_neg_exp;
+  }
+
+  { // Convert the fractional part to base 10.
+    uint64_t frac_part = 0;
+    for (int i = 0; frac && (i < NPF_MAX_FRACTION_DEC_DIGITS); ++i) {
+      frac_part *= 10;
+      frac_part += (uint64_t)(frac >> (NPF_FRACTION_BIN_DIGITS - 4));
+      frac &= 0x0fffffffffffffffllu;
+      frac *= 10;
+    }
+    *out_frac_part = frac_part;
+  }
+  return 1;
+}
+
+int npf_ftoa_rev(char *buf, float f, char case_adj, int *out_frac_chars) {
+  uint32_t f_bits; { // union-cast is UB, let compiler optimize byte-copy loop.
+    char const *src = (char const *)&f;
+    char *dst = (char *)&f_bits;
+    for (unsigned i = 0; i < sizeof(f_bits); ++i) { dst[i] = src[i]; }
+  }
+
+  if ((uint8_t)(f_bits >> 23) == 0xFF) {
+    if (f_bits & 0x7fffff) {
+      for (int i = 0; i < 3; ++i) { *buf++ = (char)("NAN"[i] + case_adj); }
+    } else {
+      for (int i = 0; i < 3; ++i) { *buf++ = (char)("FNI"[i] + case_adj); }
+    }
+    return -3;
+  }
+
+  uint64_t int_part, frac_part;
+  int frac_base10_neg_exp;
+  if (npf_fsplit_abs(f, &int_part, &frac_part, &frac_base10_neg_exp) == 0) {
+    for (int i = 0; i < 3; ++i) { *buf++ = (char)("ROO"[i] + case_adj); }
+    return -3;
+  }
+
+  char *dst = buf;
+
+  while (frac_part) { // write the fractional digits
+    *dst++ = (char)('0' + (frac_part % 10));
+    frac_part /= 10;
+  }
+
+  // write the 0 digits between the . and the first fractional digit
+  while (frac_base10_neg_exp-- > 0) { *dst++ = '0'; }
+  *out_frac_chars = (int)(dst - buf);
+  *dst++ = '.';
+
+  // write the integer digits
+  do { *dst++ = (char)('0' + (int_part % 10)); int_part /= 10; } while (int_part);
+  return (int)(dst - buf);
+}
+
+#endif // NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS
+
+#if NANOPRINTF_USE_BINARY_FORMAT_SPECIFIERS == 1
+int npf_bin_len(npf_uint_t u) {
+  // Return the length of the binary string format of 'u', preferring intrinsics.
+  if (!u) { return 1; }
+
+#ifdef _MSC_VER // Win64, use _BSR64 for everything. If x86, use _BSR when non-large.
+  #ifdef _M_X64
+    #define NPF_HAVE_BUILTIN_CLZ
+    #define NPF_CLZ _BitScanReverse64
+  #elif NANOPRINTF_USE_LARGE_FORMAT_SPECIFIERS == 0
+    #define NPF_HAVE_BUILTIN_CLZ
+    #define NPF_CLZ _BitScanReverse
+  #endif
+  #ifdef NPF_HAVE_BUILTIN_CLZ
+    unsigned long idx;
+    NPF_CLZ(&idx, u);
+    return (int)(idx + 1);
+  #endif
+#elif defined(NANOPRINTF_CLANG) || defined(NANOPRINTF_GCC_PAST_4_6)
+  #define NPF_HAVE_BUILTIN_CLZ
+  #if NANOPRINTF_USE_LARGE_FORMAT_SPECIFIERS == 1
+    #define NPF_CLZ(X) ((sizeof(long long) * 8) - (size_t)__builtin_clzll(X))
+  #else
+    #define NPF_CLZ(X) ((sizeof(long) * 8) - (size_t)__builtin_clzl(X))
+  #endif
+  return (int)NPF_CLZ(u);
+#endif
+
+#ifndef NPF_HAVE_BUILTIN_CLZ
+  int n;
+  for (n = 0; u; ++n, u >>= 1); // slow but small software fallback
+  return n;
+#else
+  #undef NPF_HAVE_BUILTIN_CLZ
+  #undef NPF_CLZ
+#endif
+}
+#endif
+
+void npf_bufputc(int c, void *ctx) {
+  npf_bufputc_ctx_t *bpc = (npf_bufputc_ctx_t *)ctx;
+  if (bpc->cur < bpc->len) { bpc->dst[bpc->cur++] = (char)c; }
+}
+
+void npf_bufputc_nop(int c, void *ctx) { (void)c; (void)ctx; }
+
+typedef struct npf_cnt_putc_ctx {
+  npf_putc pc;
+  void *ctx;
+  int n;
+} npf_cnt_putc_ctx_t;
+
+static void npf_putc_cnt(int c, void *ctx) {
+  npf_cnt_putc_ctx_t *pc_cnt = (npf_cnt_putc_ctx_t *)ctx;
+  ++pc_cnt->n;
+  pc_cnt->pc(c, pc_cnt->ctx); // sibling-call optimization
+}
+
+#define NPF_PUTC(VAL) do { npf_putc_cnt((int)(VAL), &pc_cnt); } while (0)
+
+#define NPF_EXTRACT(MOD, CAST_TO, EXTRACT_AS) \
+  case NPF_FMT_SPEC_LEN_MOD_##MOD: val = (CAST_TO)va_arg(args, EXTRACT_AS); break
+
+#define NPF_WRITEBACK(MOD, TYPE) \
+  case NPF_FMT_SPEC_LEN_MOD_##MOD: *(va_arg(args, TYPE *)) = (TYPE)pc_cnt.n; break
+
+int npf_vpprintf(npf_putc pc, void *pc_ctx, char const *format, va_list args) {
+  npf_format_spec_t fs;
+  char const *cur = format;
+  npf_cnt_putc_ctx_t pc_cnt;
+  pc_cnt.pc = pc;
+  pc_cnt.ctx = pc_ctx;
+  pc_cnt.n = 0;
+
+  while (*cur) {
+    int const fs_len = (*cur != '%') ? 0 : npf_parse_format_spec(cur, &fs);
+    if (!fs_len) { NPF_PUTC(*cur++); continue; }
+    cur += fs_len;
+
+    // Extract star-args immediately
+#if NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS == 1
+    if (fs.field_width_opt == NPF_FMT_SPEC_OPT_STAR) {
+      fs.field_width_opt = NPF_FMT_SPEC_OPT_LITERAL;
+      fs.field_width = va_arg(args, int);
+      if (fs.field_width < 0) {
+        fs.field_width = -fs.field_width;
+        fs.left_justified = 1;
+      }
+    }
+#endif
+#if NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1
+    if (fs.prec_opt == NPF_FMT_SPEC_OPT_STAR) {
+      fs.prec_opt = NPF_FMT_SPEC_OPT_NONE;
+      fs.prec = va_arg(args, int);
+      if (fs.prec >= 0) { fs.prec_opt = NPF_FMT_SPEC_OPT_LITERAL; }
+    }
+#endif
+
+    union { char cbuf_mem[32]; npf_uint_t binval; } u;
+    char *cbuf = u.cbuf_mem, sign_c = 0;
+    int cbuf_len = 0, need_0x = 0;
+#if NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS == 1
+    int field_pad = 0;
+    char pad_c = 0;
+#endif
+#if NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1
+    int prec_pad = 0;
+#if NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS == 1
+    int zero = 0;
+#endif
+#endif
+#if NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1
+    int frac_chars = 0, inf_or_nan = 0;
+#endif
+
+    // Extract and convert the argument to string, point cbuf at the text.
+    switch (fs.conv_spec) {
+      case NPF_FMT_SPEC_CONV_PERCENT:
+        *cbuf = '%';
+        cbuf_len = 1;
+        break;
+
+      case NPF_FMT_SPEC_CONV_CHAR:
+        *cbuf = (char)va_arg(args, int);
+        cbuf_len = 1;
+        break;
+
+      case NPF_FMT_SPEC_CONV_STRING: {
+        cbuf = va_arg(args, char *);
+#if NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1
+        for (char const *s = cbuf;
+             *s && ((fs.prec_opt == NPF_FMT_SPEC_OPT_NONE) || (cbuf_len < fs.prec));
+             ++s, ++cbuf_len);
+#else
+        for (char const *s = cbuf; *s; ++s, ++cbuf_len); // strlen
+#endif
+      } break;
+
+      case NPF_FMT_SPEC_CONV_SIGNED_INT: {
+        npf_int_t val = 0;
+        switch (fs.length_modifier) {
+          NPF_EXTRACT(NONE, int, int);
+          NPF_EXTRACT(SHORT, short, int);
+          NPF_EXTRACT(LONG_DOUBLE, int, int);
+          NPF_EXTRACT(CHAR, char, int);
+          NPF_EXTRACT(LONG, long, long);
+#if NANOPRINTF_USE_LARGE_FORMAT_SPECIFIERS == 1
+          NPF_EXTRACT(LARGE_LONG_LONG, long long, long long);
+          NPF_EXTRACT(LARGE_INTMAX, intmax_t, intmax_t);
+          NPF_EXTRACT(LARGE_SIZET, ssize_t, ssize_t);
+          NPF_EXTRACT(LARGE_PTRDIFFT, ptrdiff_t, ptrdiff_t);
+#endif
+          default: break;
+        }
+
+        sign_c = (val < 0) ? '-' : fs.prepend;
+
+#if NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1
+#if NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS == 1
+        zero = !val;
+#endif
+        // special case, if prec and value are 0, skip
+        if (!val && (fs.prec_opt == NPF_FMT_SPEC_OPT_LITERAL) && !fs.prec) {
+          cbuf_len = 0;
+        } else
+#endif
+        { cbuf_len = npf_itoa_rev(cbuf, val); }
+      } break;
+
+#if NANOPRINTF_USE_BINARY_FORMAT_SPECIFIERS == 1
+      case NPF_FMT_SPEC_CONV_BINARY:
+#endif
+      case NPF_FMT_SPEC_CONV_OCTAL:
+      case NPF_FMT_SPEC_CONV_HEX_INT:
+      case NPF_FMT_SPEC_CONV_UNSIGNED_INT: {
+        npf_uint_t val = 0;
+
+        switch (fs.length_modifier) {
+          NPF_EXTRACT(NONE, unsigned, unsigned);
+          NPF_EXTRACT(SHORT, unsigned short, unsigned);
+          NPF_EXTRACT(LONG_DOUBLE, unsigned, unsigned);
+          NPF_EXTRACT(CHAR, unsigned char, unsigned);
+          NPF_EXTRACT(LONG, unsigned long, unsigned long);
+#if NANOPRINTF_USE_LARGE_FORMAT_SPECIFIERS == 1
+          NPF_EXTRACT(LARGE_LONG_LONG, unsigned long long, unsigned long long);
+          NPF_EXTRACT(LARGE_INTMAX, uintmax_t, uintmax_t);
+          NPF_EXTRACT(LARGE_SIZET, size_t, size_t);
+          NPF_EXTRACT(LARGE_PTRDIFFT, size_t, size_t);
+#endif
+          default: break;
+        }
+
+#if NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1
+#if NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS == 1
+        zero = !val;
+#endif
+        if (!val && (fs.prec_opt == NPF_FMT_SPEC_OPT_LITERAL) && !fs.prec) {
+          // Zero value and explicitly-requested zero precision means "print nothing".
+          if ((fs.conv_spec == NPF_FMT_SPEC_CONV_OCTAL) && fs.alt_form) {
+            fs.prec = 1; // octal special case, print a single '0'
+          }
+        } else
+#endif
+#if NANOPRINTF_USE_BINARY_FORMAT_SPECIFIERS == 1
+        if (fs.conv_spec == NPF_FMT_SPEC_CONV_BINARY) {
+          cbuf_len = npf_bin_len(val); u.binval = val;
+        } else
+#endif
+        {
+          unsigned const base = (fs.conv_spec == NPF_FMT_SPEC_CONV_OCTAL) ?
+            8u : ((fs.conv_spec == NPF_FMT_SPEC_CONV_HEX_INT) ? 16u : 10u);
+          cbuf_len = npf_utoa_rev(cbuf, val, base, (unsigned)fs.case_adjust);
+        }
+
+        if (val && fs.alt_form && (fs.conv_spec == NPF_FMT_SPEC_CONV_OCTAL)) {
+          cbuf[cbuf_len++] = '0'; // OK to add leading octal '0' immediately.
+        }
+
+        if (val && fs.alt_form) { // 0x or 0b but can't write it yet.
+          if (fs.conv_spec == NPF_FMT_SPEC_CONV_HEX_INT) { need_0x = 'X'; }
+#if NANOPRINTF_USE_BINARY_FORMAT_SPECIFIERS == 1
+          else if (fs.conv_spec == NPF_FMT_SPEC_CONV_BINARY) { need_0x = 'B'; }
+#endif
+          if (need_0x) { need_0x += fs.case_adjust; }
+        }
+      } break;
+
+      case NPF_FMT_SPEC_CONV_POINTER: {
+        cbuf_len =
+          npf_utoa_rev(cbuf, (npf_uint_t)(uintptr_t)va_arg(args, void *), 16, 'a'-'A');
+        need_0x = 'x';
+      } break;
+
+#if NANOPRINTF_USE_WRITEBACK_FORMAT_SPECIFIERS == 1
+      case NPF_FMT_SPEC_CONV_WRITEBACK:
+        switch (fs.length_modifier) {
+          NPF_WRITEBACK(NONE, int);
+          NPF_WRITEBACK(SHORT, short);
+          NPF_WRITEBACK(LONG, long);
+          NPF_WRITEBACK(LONG_DOUBLE, double);
+          NPF_WRITEBACK(CHAR, signed char);
+#if NANOPRINTF_USE_LARGE_FORMAT_SPECIFIERS == 1
+          NPF_WRITEBACK(LARGE_LONG_LONG, long long);
+          NPF_WRITEBACK(LARGE_INTMAX, intmax_t);
+          NPF_WRITEBACK(LARGE_SIZET, size_t);
+          NPF_WRITEBACK(LARGE_PTRDIFFT, ptrdiff_t);
+#endif
+          default: break;
+        } break;
+#endif
+
+#if NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1
+      case NPF_FMT_SPEC_CONV_FLOAT_DEC:
+      case NPF_FMT_SPEC_CONV_FLOAT_SCI:
+      case NPF_FMT_SPEC_CONV_FLOAT_SHORTEST:
+      case NPF_FMT_SPEC_CONV_FLOAT_HEX: {
+        float val;
+        if (fs.length_modifier == NPF_FMT_SPEC_LEN_MOD_LONG_DOUBLE) {
+          val = (float)va_arg(args, long double);
+        } else {
+          val = (float)va_arg(args, double);
+        }
+
+        sign_c = (val < 0.f) ? '-' : fs.prepend;
+#if NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS == 1
+        zero = (val == 0.f);
+#endif
+        cbuf_len = npf_ftoa_rev(cbuf, val, fs.case_adjust, &frac_chars);
+
+        if (cbuf_len < 0) {
+          cbuf_len = -cbuf_len;
+          inf_or_nan = 1;
+        } else {
+          int const prec_adj = npf_max(0, frac_chars - fs.prec);
+          cbuf += prec_adj;
+          cbuf_len -= prec_adj;
+        }
+      } break;
+#endif
+      default: break;
+    }
+
+#if NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS == 1
+    // Compute the field width pad character
+    if (fs.field_width_opt == NPF_FMT_SPEC_OPT_LITERAL) {
+      if (fs.leading_zero_pad) { // '0' flag is only legal with numeric types
+        if ((fs.conv_spec != NPF_FMT_SPEC_CONV_STRING) &&
+            (fs.conv_spec != NPF_FMT_SPEC_CONV_CHAR) &&
+            (fs.conv_spec != NPF_FMT_SPEC_CONV_PERCENT)) {
+#if NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1
+          if ((fs.prec_opt == NPF_FMT_SPEC_OPT_LITERAL) && !fs.prec && zero) {
+            pad_c = ' ';
+          } else
+#endif
+          { pad_c = '0'; }
+        }
+      } else { pad_c = ' '; }
+    }
+#endif
+
+    // Compute the number of bytes to truncate or '0'-pad.
+    if (fs.conv_spec != NPF_FMT_SPEC_CONV_STRING) {
+#if NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1
+      if (!inf_or_nan) { // float precision is after the decimal point
+        int const prec_start =
+          (fs.conv_spec == NPF_FMT_SPEC_CONV_FLOAT_DEC) ? frac_chars : cbuf_len;
+        prec_pad = npf_max(0, fs.prec - prec_start);
+      }
+#elif NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1
+      prec_pad = npf_max(0, fs.prec - cbuf_len);
+#endif
+    }
+
+#if NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS == 1
+    // Given the full converted length, how many pad bytes?
+    field_pad = fs.field_width - cbuf_len - !!sign_c;
+    if (need_0x) { field_pad -= 2; }
+
+#if NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1
+    if ((fs.conv_spec == NPF_FMT_SPEC_CONV_FLOAT_DEC) && !fs.prec && !fs.alt_form) {
+      ++field_pad; // 0-pad, no decimal point.
+    }
+#endif
+#if NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1
+    field_pad -= prec_pad;
+#endif
+    field_pad = npf_max(0, field_pad);
+#endif // NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS
+
+#if NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS == 1
+    // Apply right-justified field width if requested
+    if (!fs.left_justified && pad_c) { // If leading zeros pad, sign goes first.
+      if (pad_c == '0') {
+        if (sign_c) { NPF_PUTC(sign_c); sign_c = 0; }
+        // Pad byte is '0', write '0x' before '0' pad chars.
+        if (need_0x) { NPF_PUTC('0'); NPF_PUTC(need_0x); }
+      }
+      while (field_pad-- > 0) { NPF_PUTC(pad_c); }
+      // Pad byte is ' ', write '0x' after ' ' pad chars but before number.
+      if ((pad_c != '0') && need_0x) { NPF_PUTC('0'); NPF_PUTC(need_0x); }
+    } else
+#endif
+    { if (need_0x) { NPF_PUTC('0'); NPF_PUTC(need_0x); } } // no pad, '0x' requested.
+
+    // Write the converted payload
+    if (fs.conv_spec == NPF_FMT_SPEC_CONV_STRING) {
+      for (int i = 0; i < cbuf_len; ++i) { NPF_PUTC(cbuf[i]); }
+    } else {
+      if (sign_c) { NPF_PUTC(sign_c); }
+#if NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1
+      if (fs.conv_spec != NPF_FMT_SPEC_CONV_FLOAT_DEC) {
+#endif
+
+#if NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1
+        while (prec_pad-- > 0) { NPF_PUTC('0'); } // int precision leads.
+#endif
+
+#if NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1
+      } else {
+        // if 0 precision, skip the fractional part and '.'
+        // if 0 prec + alternative form, keep the '.'
+        if (!fs.prec && !fs.alt_form) { ++cbuf; --cbuf_len; }
+      }
+#endif
+
+#if NANOPRINTF_USE_BINARY_FORMAT_SPECIFIERS == 1
+      if (fs.conv_spec == NPF_FMT_SPEC_CONV_BINARY) {
+        while (cbuf_len) { NPF_PUTC('0' + ((u.binval >> --cbuf_len) & 1)); }
+      } else
+#endif
+      { while (cbuf_len-- > 0) { NPF_PUTC(cbuf[cbuf_len]); } } // payload is reversed
+
+#if NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1
+      // real precision comes after the number.
+      if ((fs.conv_spec == NPF_FMT_SPEC_CONV_FLOAT_DEC) && !inf_or_nan) {
+        while (prec_pad-- > 0) { NPF_PUTC('0'); }
+      }
+#endif
+    }
+
+#if NANOPRINTF_USE_FIELD_WIDTH_FORMAT_SPECIFIERS == 1
+    if (fs.left_justified && pad_c) { // Apply left-justified field width
+      while (field_pad-- > 0) { NPF_PUTC(pad_c); }
+    }
+#endif
+  }
+
+  return pc_cnt.n;
+}
+
+#undef NPF_PUTC
+#undef NPF_EXTRACT
+#undef NPF_WRITEBACK
+
+int npf_pprintf(npf_putc pc, void *pc_ctx, char const *format, ...) {
+  va_list val;
+  va_start(val, format);
+  int const rv = npf_vpprintf(pc, pc_ctx, format, val);
+  va_end(val);
+  return rv;
+}
+
+int npf_snprintf(char *buffer, size_t bufsz, const char *format, ...) {
+  va_list val;
+  va_start(val, format);
+  int const rv = npf_vsnprintf(buffer, bufsz, format, val);
+  va_end(val);
+  return rv;
+}
+
+int npf_vsnprintf(char *buffer, size_t bufsz, char const *format, va_list vlist) {
+  npf_bufputc_ctx_t bufputc_ctx;
+  bufputc_ctx.dst = buffer;
+  bufputc_ctx.len = bufsz;
+  bufputc_ctx.cur = 0;
+
+  npf_putc const pc = buffer ? npf_bufputc : npf_bufputc_nop;
+  int const n = npf_vpprintf(pc, &bufputc_ctx, format, vlist);
+  pc('\0', &bufputc_ctx);
+
+#ifdef NANOPRINTF_SNPRINTF_SAFE_EMPTY_STRING_ON_OVERFLOW
+  if (bufsz && (n >= (int)bufsz)) { buffer[0] = '\0'; }
+#elif defined(NANOPRINTF_SNPRINTF_SAFE_TRIM_STRING_ON_OVERFLOW)
+  if (bufsz && (n >= (int)bufsz)) { buffer[bufsz - 1] = '\0'; }
+#endif
+
+  return n;
+}
+
+#if NANOPRINTF_HAVE_GCC_WARNING_PRAGMAS
+  #pragma GCC diagnostic pop
+#endif
+
+#ifdef _MSC_VER
+  #pragma warning(pop)
+#endif
+
+#endif // NANOPRINTF_IMPLEMENTATION_INCLUDED
+#endif // NANOPRINTF_IMPLEMENTATION
+
+/*
+  nanoprintf is dual-licensed under both the "Unlicense" and the
+  "Zero-Clause BSD" (0BSD) licenses. The intent of this dual-licensing
+  structure is to make nanoprintf as consumable as possible in as many
+  environments / countries / companies as possible without any
+  encumberances.
+
+  The text of the two licenses follows below:
+
+  ============================== UNLICENSE ==============================
+
+  This is free and unencumbered software released into the public domain.
+
+  Anyone is free to copy, modify, publish, use, compile, sell, or
+  distribute this software, either in source code form or as a compiled
+  binary, for any purpose, commercial or non-commercial, and by any
+  means.
+
+  In jurisdictions that recognize copyright laws, the author or authors
+  of this software dedicate any and all copyright interest in the
+  software to the public domain. We make this dedication for the benefit
+  of the public at large and to the detriment of our heirs and
+  successors. We intend this dedication to be an overt act of
+  relinquishment in perpetuity of all present and future rights to this
+  software under copyright law.
+
+  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 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.
+
+  For more information, please refer to <http://unlicense.org>
+
+  ================================ 0BSD =================================
+
+  Copyright (C) 2019- by Charles Nicholson <charles.nicholson+nanoprintf@gmail.com>
+
+  Permission to use, copy, modify, and/or distribute this software for
+  any purpose with or without fee is hereby granted.
+
+  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
diff --git a/Makefile.deps b/Makefile.deps
index c5dfd19..9694671 100644
--- a/Makefile.deps
+++ b/Makefile.deps
@@ -57,6 +57,11 @@ $(LIBCRT_BUILD_DIR)/ntdll_zw_functions$(NAME_SUFFIX).o: $(CC) $(DPP_ROOT)/CRT/nt
 	$(Q)$(CC) -std=c99 $(CFLAGS) -c CRT/ntdll_zw_functions.c -o $@
 	@echo 'CC  $@'
 
+$(LIBCRT_BUILD_DIR)/eastl_compat$(NAME_SUFFIX).opp: $(CXX) $(DPP_ROOT)/CRT/eastl_compat.cpp
+	$(Q)test -d '$(LIBCRT_BUILD_DIR)' || mkdir -p '$(LIBCRT_BUILD_DIR)'
+	$(Q)$(CXX) $(CFLAGS) $(CXXFLAGS) $(EASTL_CXXFLAGS) -c CRT/eastl_compat.cpp -o $@
+	@echo 'CXX $@'
+
 $(LIBCRT_BUILD_DIR)/kcrt$(NAME_SUFFIX).opp: $(CXX) $(DPP_ROOT)/CRT/kcrt.cpp
 	$(Q)test -d '$(LIBCRT_BUILD_DIR)' || mkdir -p '$(LIBCRT_BUILD_DIR)'
 	$(Q)$(CXX) $(CFLAGS) $(CXXFLAGS) $(EASTL_CXXFLAGS) -c CRT/kcrt.cpp -o $@
diff --git a/Makefile.inc b/Makefile.inc
index 24c907b..0b23309 100644
--- a/Makefile.inc
+++ b/Makefile.inc
@@ -65,6 +65,7 @@ EASTL_CXXFLAGS := -I$(DPP_ROOT)/EASTL/include -I$(DPP_ROOT)/EASTL/test/packages/
 	-DEASTL_THREAD_SUPPORT_AVAILABLE=0 \
 	-DEASTL_EXCEPTIONS_ENABLED=0 \
 	-DEASTL_ASSERT_ENABLED=0 \
+	-DEASTL_EASTDC_VSNPRINTF=0 \
 	-DEA_COMPILER_NO_EXCEPTIONS=1 \
 	-DEA_COMPILER_MANAGED_CPP=1 \
 	-Wno-unknown-pragmas \
@@ -92,6 +93,7 @@ LIBCRT_OBJECTS := \
 	$(LIBCRT_BUILD_DIR)/kcrt$(NAME_SUFFIX).o \
 	$(LIBCRT_BUILD_DIR)/ntdll_zw_functions$(NAME_SUFFIX).o
 LIBCXXRT_OBJECTS := \
+	$(LIBCRT_BUILD_DIR)/eastl_compat$(NAME_SUFFIX).opp \
 	$(LIBCRT_BUILD_DIR)/kcrt$(NAME_SUFFIX).opp \
 	$(LIBCRT_BUILD_DIR)/DriverThread$(NAME_SUFFIX).opp
 LIBUSERCRT_OBJECTS := $(LIBCRT_BUILD_DIR)/ucrt$(NAME_SUFFIX).opp
diff --git a/README.md b/README.md
index 6c6526c..7889cb5 100644
--- a/README.md
+++ b/README.md
@@ -195,6 +195,11 @@ You may reach a point where system functions, intrinsics or built-ins are requir
 For system functions that can be retrieved via `MmGetSystemRoutineAddress`, you may use `CRT/gen_wrapper.sh` to create wrapper modules. These modules retrieve the desired functions during run-time, but will be available during link-time. An example is `ZwTraceControl`, which gets exported by `ntdll.dll`.
 Eventually missing intrinsics/built-ins should be placed in `CRT/kcrt.c`.
 
+## Known Issues
+
+Unfortunately, `eastl::to_string` does not work. See `CRT/eastl_compat.cpp` for more details.
+Instead, `#include <eastl_compat.hpp>` and use `::to_string` globals.
+
 ## Thanks goes to:
 
 - [Zeranoe](https://github.com/Zeranoe/mingw-w64-build) for the Mingw64 build script
diff --git a/examples/dpp-example-cplusplus.cpp b/examples/dpp-example-cplusplus.cpp
index 980922d..736fb32 100644
--- a/examples/dpp-example-cplusplus.cpp
+++ b/examples/dpp-example-cplusplus.cpp
@@ -1,5 +1,7 @@
 #include <ntddk.h>
 
+#include <EASTL/string.h>
+#include <eastl_compat.hpp>
 #include <DriverThread.hpp>
 
 class TestSmth
@@ -16,6 +18,23 @@ public:
     void doSmth(void)
     {
         DbgPrint("%s\n", "Hello Class!");
+
+        const auto & number_ud = ::to_string(1337u);
+        DbgPrint("Value 1337u to String: %s\n", number_ud.c_str());
+        const auto & number_d = ::to_string(1337);
+        DbgPrint("Value 1337 to String: %s\n", number_d.c_str());
+        const auto & number_l = ::to_string(1337l);
+        DbgPrint("Value 1337l to String: %s\n", number_l.c_str());
+        const auto & number_lu = ::to_string(1337lu);
+        DbgPrint("Value 1337lu to String: %s\n", number_lu.c_str());
+        const auto & number_ll = ::to_string(1337ll);
+        DbgPrint("Value 1337ll to String: %s\n", number_ll.c_str());
+        const auto & number_llu = ::to_string(1337llu);
+        DbgPrint("Value 1337llu to String: %s\n", number_llu.c_str());
+        const auto & number_f = ::to_string(1337.1337f);
+        DbgPrint("Value 1337f to String: %s\n", number_f.c_str());
+        const auto & number_lf = ::to_string(1337.1337);
+        DbgPrint("Value 1337lf to String: %s\n", number_lf.c_str());
     }
 };
 static TestSmth * cdtor_test;
diff --git a/update_nanoprintf.sh b/update_nanoprintf.sh
new file mode 100755
index 0000000..fba3e7a
--- /dev/null
+++ b/update_nanoprintf.sh
@@ -0,0 +1,6 @@
+#!/usr/bin/env sh
+
+MYDIR="$(dirname ${0})"
+cd "${MYDIR}"
+
+wget 'https://raw.githubusercontent.com/charlesnicholson/nanoprintf/main/nanoprintf.h' -O 'CRT/nanoprintf.h'