shell: support floating point output with newlib

shell_fprintf requires that formatted output be emitted with a
putchar()-like output function.  Newlib does not provide such a
capability.  Zephyr provides two solutions: z_prf() which is part of
minimal libc and handles floating point formatting, and z_vprintk()
which is core and does not support floating point.

Move z_prf() out of minimal libc into the core lib area, and use it
unconditionally in the shell.

Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>

lib/libc/minimal/CMakeLists.txt

@@ -14,7 +14,6 @@ zephyr_library_sources(
   source/string/strstr.c
   source/string/string.c
   source/string/strspn.c
-  source/stdout/prf.c
   source/stdout/stdout_console.c
   source/stdout/sprintf.c
   source/stdout/fprintf.c

lib/os/CMakeLists.txt

@@ -23,6 +23,9 @@ zephyr_sources(
   heap-validate.c
   )
 
+zephyr_sources_ifdef(CONFIG_MINIMAL_LIBC prf.c)
+zephyr_sources_ifdef(CONFIG_SHELL prf.c)
+
 zephyr_sources_ifdef(CONFIG_JSON_LIBRARY json.c)
 
 zephyr_sources_ifdef(CONFIG_RING_BUFFER ring_buffer.c)

subsys/shell/shell_fprintf.c

@@ -7,12 +7,7 @@
 #include <shell/shell_fprintf.h>
 #include <shell/shell.h>
 
-#ifdef CONFIG_NEWLIB_LIBC
-typedef int (*out_func_t)(int c, void *ctx);
-extern void z_vprintk(out_func_t out, void *ctx, const char *fmt, va_list ap);
-#else
 extern int z_prf(int (*func)(), void *dest, char *format, va_list vargs);
-#endif
 
 static int out_func(int c, void *ctx)
 {
@@ -39,11 +34,7 @@ static int out_func(int c, void *ctx)
 void shell_fprintf_fmt(const struct shell_fprintf *sh_fprintf,
 		       const char *fmt, va_list args)
 {
-#if !defined(CONFIG_NEWLIB_LIBC) && !defined(CONFIG_ARCH_POSIX)
 	(void)z_prf(out_func, (void *)sh_fprintf, (char *)fmt, args);
-#else
-	z_vprintk(out_func, (void *)sh_fprintf, fmt, args);
-#endif
 
 	if (sh_fprintf->ctrl_blk->autoflush) {
 		shell_fprintf_buffer_flush(sh_fprintf);