xlib (klib)

Freestanding C library for programs built by xam and run on xemu. Modelled after NEMU's abstract-machine klib — minimal, deterministic, platform-independent.

See ../../spec/klib/SPEC.md for the design.

What's included

<string.h> — string.c

void  *memset(void *s, int c, size_t n);
void  *memcpy(void *dst, const void *src, size_t n);
void  *memmove(void *dst, const void *src, size_t n);
int    memcmp(const void *s1, const void *s2, size_t n);

size_t strlen(const char *s);
char  *strcpy(char *dst, const char *src);
char  *strncpy(char *dst, const char *src, size_t n);
char  *strcat(char *dst, const char *src);
int    strcmp(const char *s1, const char *s2);
int    strncmp(const char *s1, const char *s2, size_t n);
char  *strchr(const char *s, int c);
char  *strrchr(const char *s, int c);

<stdio.h> — stdio.c + format.c

int printf(const char *fmt, ...);
int sprintf(char *buf, const char *fmt, ...);
int snprintf(char *buf, size_t size, const char *fmt, ...);
int vsprintf(char *buf, const char *fmt, va_list ap);
int vsnprintf(char *buf, size_t size, const char *fmt, va_list ap);
int puts(const char *s);
int putch(char ch);

Format specifiers: %d %i %u %x %X %s %c %p %o %%, with l / ll length modifiers, field width, 0-padding, left-alignment. No floating-point printf.

<assert.h>

#define assert(x) ...

C- and C++-compatible (carries extern "C" guards).

<stdlib.h> — stdlib.c

int     atoi(const char *s);
int     abs(int x);
void    srand(unsigned seed);
int     rand(void);

No malloc / free — cpu-tests don't need them, benchmarks use local allocators.

<ctype.h> — ctype.c

isspace, isdigit, isalpha, isalnum, toupper, tolower, etc. Standard shapes.

What's not included

• POSIX APIs, FILE * streams.
• Floating-point printf.
• Locale support.
• Thread-safe allocation.

This is intentional — xlib targets bare-metal test and benchmark kernels, not a hosted C environment.

Using from your kernel

#include <klib.h>          /* umbrella header */

This pulls in <stddef.h>, <stdint.h>, <stdbool.h>, <stdarg.h>, <string.h>, <stdio.h>, <stdlib.h>, <ctype.h>. The xam build system prepends -I$(XLIB_HOME)/include before system includes.

klib-macros.h

Convenience macros used by benchmarks:

#define LENGTH(arr)        (sizeof(arr) / sizeof((arr)[0]))
#define ROUNDUP(x, n)      (((x) + (n) - 1) & ~((n) - 1))
#define ROUNDDOWN(x, n)    ((x) & ~((n) - 1))
#define MIN(a, b)          ((a) < (b) ? (a) : (b))
#define MAX(a, b)          ((a) > (b) ? (a) : (b))