include: create the basics of a libc

Create the most basic files for a POSIX-conformant standard C library
implementation. These basic files should be enough to get the bootloader
and kernel off the ground and not much else. Additional testing should
be done on these files.

Signed-off-by: Danny Holman <dholman@gymli.org>

1 files changed, 83 insertions, 0 deletions

diff --git a/include/limits.h b/include/limits.h
new file mode 100644
index 0000000..6ee065d
--- /dev/null
+++ b/include/limits.h
@@ -0,0 +1,83 @@
+/*
+ * Copyright (C) 2025 Danny Holman <dholman@gymli.org>
+ *
+ * This file is part of BoxOS, a free and open-source Unix-like operating
+ * system.
+ *
+ * BoxOS is free software; you can redistribute it and/or modify under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 2 of the License, or (at your option) any later
+ * version.
+ *
+ * BoxOS is distributed in the hope it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE. See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * BoxOS; if not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef LIMITS_H
+#define LIMITS_H
+
+#define CHAR_BIT        8
+#define SCHAR_MIN       (-128)
+#define SCHAR_MAX       127
+#define UCHAR_MAX       255
+
+#define CHAR_MIN        SCHAR_MIN
+#define CHAR_MAX        SCHAR_MAX
+
+#define SHRT_MIN        (-32768)
+#define SHRT_MAX        32767
+#define USHRT_MAX       65535
+
+#define INT_MIN         (-2147483648)
+#define INT_MAX         2147483647
+#define UINT_MAX        4294967295U
+
+#define LONG_MIN        (-9223372036854775808L)
+#define LONG_MAX        9223372036854775807L
+#define ULONG_MAX       18446744073709551615UL
+
+#define FLT_RADIX       2
+#define FLT_MANT_DIG    24
+#define FLT_DIG         6
+#define FLT_MIN         1.175494351e-38F
+#define FLT_MAX         3.402823466e+38F
+
+#define DBL_MANT_DIG    53
+#define DBL_DIG         15
+#define DBL_MIN         2.2250738585072014e-308
+#define DBL_MAX         1.7976931348623157e+308
+
+#define INT8_MIN        (-1-0x7F)
+#define INT16_MIN       (-1-0x7FFF)
+#define INT32_MIN       (-1-0x7FFFFFFF)
+#define INT64_MIN       (-1-0x7FFFFFFFFFFFFFFF)
+
+#define INT8_MAX        (0x7F)
+#define INT16_MAX       (0x7FFF)
+#define INT32_MAX       (0x7FFFFFFF)
+#define INT64_MAX       (0x7FFFFFFFFFFFFFFF)
+
+#define UINT8_MAX       (0xFF)
+#define UINT16_MAX      (0xFFFF)
+#define UINT32_MAX      (0xFFFFFFFF)
+#define UINT64_MAX      (0xFFFFFFFFFFFFFFFF)
+
+#define INTPTR_MAX      INT64_MAX
+#define UINTPTR_MAX     UINT64_MAX
+
+#define INT_FAST8_MIN   INT8_MIN
+#define INT_FAST64_MIN  INT64_MIN
+
+#define INT_FAST8_MAX   INT8_MAX
+#define INT_FAST64_MAX  INT64_MAX
+
+#define INT_LEAST8_MIN  INT8_MIN
+#define INT_LEAST16_MIN INT16_MIN
+#define INT_LEAST32_MIN INT32_MIN
+#define INT_LEAST64_MIN INT64_MIN
+
+#endif