feat(ctype): classification and case-mapping tables

include/ctype.h

@@ -0,0 +1,164 @@
+#ifndef VLIBC_CTYPE_H
+#define VLIBC_CTYPE_H
+
+/*
+ * vlibc — <ctype.h>.
+ *
+ * Character classification and case mapping. Every function takes an int
+ * that represents an unsigned char value or EOF (-1). The implementation
+ * always casts the argument to unsigned char before any table lookup, so a
+ * negative char value can never index out of bounds; EOF classifies false
+ * in every is* function, and tolower/toupper pass it (and every non-letter)
+ * through unchanged. All results are for the "C" locale.
+ *
+ * Levels are cumulative (see include/vlibc/features.h):
+ *   Level 1 (onlyposix): ISO C — the classification and case-mapping
+ *                        functions.
+ *   Level 2 (muslmimic): XSI — isascii, toascii.
+ *
+ * This header includes <vlibc/features.h> itself, so the gates below always
+ * see the configured VLIBC_LEVEL even when the caller included no vlibc
+ * header first. The classification functions return exactly 1 when the
+ * character is in the class and 0 otherwise, never any other nonzero value.
+ */
+
+#include <vlibc/features.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Level 1: ISO C (always present). */
+
+/*
+ * Nonzero when c is alphanumeric: a letter or a decimal digit.
+ * pure: reads the classification table, no side effects.
+ */
+__attribute__((pure)) int
+isalnum(int c);
+
+/*
+ * Nonzero when c is a letter.
+ * pure: reads the classification table, no side effects.
+ */
+__attribute__((pure)) int
+isalpha(int c);
+
+/*
+ * Nonzero when c is blank: space or horizontal tab.
+ * pure: reads the classification table, no side effects.
+ */
+__attribute__((pure)) int
+isblank(int c);
+
+/*
+ * Nonzero when c is a control character (0x00..0x1f or 0x7f).
+ * pure: reads the classification table, no side effects.
+ */
+__attribute__((pure)) int
+iscntrl(int c);
+
+/*
+ * Nonzero when c is a decimal digit.
+ * const: bit arithmetic on the argument alone (also matches GCC's const
+ * builtin declaration for isdigit).
+ */
+__attribute__((const)) int
+isdigit(int c);
+
+/*
+ * Nonzero when c has a visible representation (printable, except space).
+ * pure: reads the classification table, no side effects.
+ */
+__attribute__((pure)) int
+isgraph(int c);
+
+/*
+ * Nonzero when c is a lowercase letter.
+ * pure: reads the classification table, no side effects.
+ */
+__attribute__((pure)) int
+islower(int c);
+
+/*
+ * Nonzero when c is printable (0x20..0x7e).
+ * pure: the implementation is bit arithmetic on the argument alone, but
+ * GCC's isprint builtin is declared pure, and a const redeclaration would
+ * conflict with it.
+ */
+__attribute__((pure)) int
+isprint(int c);
+
+/*
+ * Nonzero when c is a punctuation character: printable and not alphanumeric
+ * and not space.
+ * pure: reads the classification table, no side effects.
+ */
+__attribute__((pure)) int
+ispunct(int c);
+
+/*
+ * Nonzero when c is white space (space, form feed, newline, carriage
+ * return, horizontal or vertical tab).
+ * pure: reads the classification table, no side effects.
+ */
+__attribute__((pure)) int
+isspace(int c);
+
+/*
+ * Nonzero when c is an uppercase letter.
+ * pure: reads the classification table, no side effects.
+ */
+__attribute__((pure)) int
+isupper(int c);
+
+/*
+ * Nonzero when c is a hexadecimal digit (0-9, a-f, A-F).
+ * const: bit arithmetic on the argument alone (also matches GCC's const
+ * builtin declaration for isxdigit).
+ */
+__attribute__((const)) int
+isxdigit(int c);
+
+/*
+ * Return the lowercase counterpart of c when c is an uppercase letter
+ * ('A'..'Z' in the "C" locale); otherwise return c unchanged, including
+ * EOF.
+ * pure: reads the classification table, no side effects.
+ */
+__attribute__((pure)) int
+tolower(int c);
+
+/*
+ * Return the uppercase counterpart of c when c is a lowercase letter
+ * ('a'..'z' in the "C" locale); otherwise return c unchanged, including
+ * EOF.
+ * pure: reads the classification table, no side effects.
+ */
+__attribute__((pure)) int
+toupper(int c);
+
+#if VLIBC_LEVEL_GE(2)
+/* Level 2 (muslmimic): XSI. */
+
+/*
+ * Nonzero when c is a 7-bit ASCII value (0..127). EOF and negative values
+ * are outside the range.
+ * const: depends only on its argument.
+ */
+__attribute__((const)) int
+isascii(int c);
+
+/*
+ * Clear every bit above the low 7 of c (c & 0x7f).
+ * const: depends only on its argument.
+ */
+__attribute__((const)) int
+toascii(int c);
+#endif /* VLIBC_LEVEL_GE(2) */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* VLIBC_CTYPE_H */