refactor: libc - share printf, split the float path, fix relink deps

2026-08-04 17:29:24 +02:00
parent edc3452d61
commit 75d92d560c
39 changed files with 388 additions and 586 deletions
@@ -0,0 +1,39 @@
+/*
+    * printf_internal.h
+    * Shared state between the integer printf core (libc.c) and the optional
+    * floating-point conversion module (printf_float.c).
+    * Copyright (c) 2026 Daniel Hammer
+*/
+
+#ifndef _LIBC_PRINTF_INTERNAL_H
+#define _LIBC_PRINTF_INTERNAL_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+/* Output cursor shared by every conversion. `pos` counts the characters a
+   conversion WOULD have written, so it may run past `max`; only writes below
+   `max` land in `buf`. That is what gives snprintf its C99 return value. */
+struct _pf_state {
+    char  *buf;
+    size_t pos;
+    size_t max;
+};
+
+/* Defined in libc.c. External rather than static so the float module can
+   reach it; it is the only core helper the float conversions need. */
+void _pf_putc(struct _pf_state *st, char c);
+
+/* Union for double bit manipulation (used by float formatting and math). */
+typedef union { double d; uint64_t u; } _dbl_bits;
+
+/* Defined in printf_float.c, which is a SEPARATE archive member so that
+   --gc-sections can drop the decimal-conversion and pow/exp/log code from
+   programs that never format a float. vsnprintf calls this through a WEAK
+   reference: link with -Wl,-u,_pf_putfloat to pull the module in. Without
+   that flag %e/%f/%g echo their conversion spec instead of a number. */
+void _pf_putfloat(struct _pf_state *st, double v, char conv,
+                  int precision, int width, char pad,
+                  int left_align, int plus, int space, int alt);
+
+#endif /* _LIBC_PRINTF_INTERNAL_H */