Add option 'PRINTF_ONLY_FCTPRINTF' to compile the library without functions that depend on putchar_.

CMakeLists.txt

@@ -22,6 +22,7 @@ option(SUPPORT_WRITEBACK_SPECIFIER            "Support the length write-back spe
 option(SUPPORT_LONG_LONG                      "Support long long integral types (allows for the ll length modifier and affects %p)" ON)
 option(USE_DOUBLE_INTERNALLY                  "Use the C `double` type - typically 64-bit in size - for internal floating-point arithmetic " ON)
 option(CHECK_FOR_NUL_IN_FORMAT_SPECIFIER      "Be defensive in the undefined-behavior case of a format specifier not ending before the string ends" ON)
+option(PROVIDE_PLAIN_PRINTF                   "Provide the plain printf() and vprintf() functions, requiring a putchar_() primitive" ON)
 
 set(ALIASING_MODES NONE HARD SOFT)
 set(ALIAS_STANDARD_FUNCTION_NAMES NONE CACHE STRING "Alias the standard library function names (printf, sprintf etc.) to the library's functions - concretely, via a macro, or not at all")
@@ -43,6 +44,7 @@ foreach(opt
 	ALIAS_STANDARD_FUNCTION_NAMES_SOFT
 	ALIAS_STANDARD_FUNCTION_NAMES_HARD
 	CHECK_FOR_NUL_IN_FORMAT_SPECIFIER
+    PROVIDE_PLAIN_PRINTF
 )
 	if (${${opt}})
 		set("PRINTF_${opt}" 1)
@@ -83,7 +85,10 @@ add_library("printf::printf" ALIAS printf)
 
 set(GENERATED_INCLUDE_DIR "${CMAKE_CURRENT_BINARY_DIR}/include")
 configure_file("printf_config.h.in" "${GENERATED_INCLUDE_DIR}/printf_config.h" @ONLY)
-target_sources(printf PRIVATE src/printf/printf.c "${GENERATED_INCLUDE_DIR}/printf_config.h" src/printf/printf.h)
+target_sources(printf PRIVATE src/printf/printf_core.c "${GENERATED_INCLUDE_DIR}/printf_config.h" src/printf/internal.h src/printf/printf.h)
+if(PROVIDE_PLAIN_PRINTF)
+    target_sources(printf PRIVATE src/printf/printf.c)
+endif()
 target_compile_definitions(printf PRIVATE PRINTF_INCLUDE_CONFIG_H)
 target_include_directories(printf PRIVATE "$<BUILD_INTERFACE:${GENERATED_INCLUDE_DIR}>")
 
@@ -162,7 +167,7 @@ if (UNIX)
 		COMMAND objdump --disassemble --line-numbers -S "$<TARGET_FILE:printf>" > printf.list
 		DEPENDS printf
 		BYPRODUCTS printf.lst
-		COMMENT Dissassembles the compiled library into an .lst file)
+		COMMENT Disassembles the compiled library into an .lst file)
 
 endif()
 
@@ -186,6 +191,7 @@ install(
 
 install(
 	FILES "src/printf/printf.h"
+	FILES "${GENERATED_INCLUDE_DIR}/printf_config.h"
 	DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/printf"
 )
 

README.md

@@ -102,6 +102,7 @@ Options used both in CMake and in the library source code via a preprocessor def
 | PRINTF_SUPPORT_WRITEBACK_SPECIFIER     | YES     |  Support the length write-back specifier (%n) |
 | PRINTF_SUPPORT_LONG_LONG               | YES     |  Support long long integral types (allows for the ll length modifier and affects %p) |
 | PRINTF_USE_DOUBLE_INTERNALLY           | YES     |  Use the `double` for internal floating-point calculations (rather than using the single-precision `float` type |
+| PRINTF_PROVIDE_PLAIN_PRINTF            | YES     | Provide the plain printf() and vprintf() functions, requiring a putchar_() primitive |
 
 Within CMake, these options lack the `PRINTF_` prefix.
 
@@ -115,7 +116,7 @@ Source-only options:
 
 | Option name                            | Default | Description  |
 |----------------------------------------|---------|--------------|
-| PRINTF_INCLUDE_CONFIG_H                | NO      |  Triggers inclusing by `printf.c` of a "printf_config.h" file, which in turn contains the values of all of the CMake-and-preprocessor options above. A CMake build of the library uses this mechanism to apply the user's choice of options, so it can't have the mechanism itself as an option. |
+| PRINTF_INCLUDE_CONFIG_H                | NO      |  Triggers including by `printf.c` of a "printf_config.h" file, which in turn contains the values of all of the CMake-and-preprocessor options above. A CMake build of the library uses this mechanism to apply the user's choice of options, so it can't have the mechanism itself as an option. |
 
 Note: The preprocessor definitions are taken into account mostly when compiling `printf.c`.
 

printf_config.h.in

@@ -17,6 +17,7 @@
 #define PRINTF_MAX_INTEGRAL_DIGITS_FOR_DECIMAL  @MAX_INTEGRAL_DIGITS_FOR_DECIMAL@
 #define PRINTF_LOG10_TAYLOR_TERMS               @LOG10_TAYLOR_TERMS@
 #define PRINTF_CHECK_FOR_NUL_IN_FORMAT_SPECIFIER @PRINTF_CHECK_FOR_NUL_IN_FORMAT_SPECIFIER@
+#define PRINTF_PROVIDE_PLAIN_PRINTF             @PRINTF_PROVIDE_PLAIN_PRINTF@
 
 #endif /* PRINTF_CONFIG_H_ */
 

src/printf/internal.h

@@ -0,0 +1,71 @@
+#ifndef PRINTF_INTERNAL_H_
+#define PRINTF_INTERNAL_H_
+
+#include <printf/printf.h>
+#include <limits.h>
+
+#if !(defined(__cplusplus) || (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L))
+/* C90 */
+#if defined(_MSC_VER)
+#define inline __inline
+#else
+#define inline __inline__
+#endif /* defined(_MSC_VER) */
+#endif /* !(defined(__cplusplus) || (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L)) */
+
+/*
+ * The printf()-family functions return an `int`; it is therefore
+ * unnecessary/inappropriate to use size_t - often larger than int
+ * in practice - for non-negative related values, such as widths,
+ * precisions, offsets into buffers used for printing and the sizes
+ * of these buffers. instead, we use:
+ */
+typedef unsigned int printf_size_t;
+#define PRINTF_MAX_POSSIBLE_BUFFER_SIZE INT_MAX
+  /*
+   * If we were to nitpick, this would actually be INT_MAX + 1,
+   * since INT_MAX is the maximum return value, which excludes the
+   * trailing '\0'.
+   */
+
+/*
+ * wrapper (used as buffer) for output function type
+ *
+ * One of the following must hold:
+ * 1. max_chars is 0
+ * 2. buffer is non-null
+ * 3. function is non-null
+ *
+ * ... otherwise bad things will happen.
+ */
+typedef struct {
+  void (*function)(char c, void* extra_arg);
+  void* extra_function_arg;
+  char* buffer;
+  printf_size_t pos;
+  printf_size_t max_chars;
+} output_gadget_t;
+
+static inline output_gadget_t discarding_gadget(void)
+{
+  output_gadget_t gadget;
+  gadget.function = NULL;
+  gadget.extra_function_arg = NULL;
+  gadget.buffer = NULL;
+  gadget.pos = 0;
+  gadget.max_chars = 0;
+  return gadget;
+}
+
+static inline output_gadget_t function_gadget(void (*function)(char, void*), void* extra_arg)
+{
+  output_gadget_t result = discarding_gadget();
+  result.function = function;
+  result.extra_function_arg = extra_arg;
+  result.max_chars = PRINTF_MAX_POSSIBLE_BUFFER_SIZE;
+  return result;
+}
+
+int eyalroz_vsnprintf_impl(output_gadget_t* output, const char* format, va_list args);
+
+#endif /* PRINTF_INTERNAL_H_ */