diff options
| -rw-r--r-- | c/bit_array.c | 105 | ||||
| -rw-r--r-- | c/bit_compose.c | 32 | ||||
| -rwxr-xr-x | c/do | 6 | ||||
| -rw-r--r-- | c/malloc_hook.c | 37 |
4 files changed, 180 insertions, 0 deletions
diff --git a/c/bit_array.c b/c/bit_array.c new file mode 100644 index 0000000..26c05f6 --- /dev/null +++ b/c/bit_array.c @@ -0,0 +1,105 @@ +#include <stdint.h> +#include <stdlib.h> +#include <string.h> +#include <stdio.h> + +typedef uint32_t bitfield_t; +enum { BITFIELD_BITS = sizeof(bitfield_t) * 8 }; + +static inline int bindex(int b) { return b / BITFIELD_BITS; } +static inline int boffset(int b) { return b % BITFIELD_BITS; } +#define bptr(st) (&((st)->bits)) + +struct _Bits +{ + uint32_t nw; + bitfield_t bits; +}; + +typedef struct _Bits * Bits; + +static inline Bits bits_alloc(int n) +{ + uint32_t nw = (n / BITFIELD_BITS); + if (nw * BITFIELD_BITS < n) nw += 1; + int sz = sizeof(int) + (nw * sizeof(bitfield_t)); + /* printf("wants %d bits : alloc %d bytes (1 uint32_t[%lu] + %d bitfields[%lu])\n", n, sz, sizeof(uint32_t), nw, (nw * sizeof(bitfield_t))); */ + Bits b = calloc(1, sz); + /* memset(b, 0, sz); */ + b->nw = nw; + return b; +} + +static inline void bits_free(Bits bits) +{ + free(bits); +} + +static inline void set_bit(Bits bits, int b) +{ + bptr(bits)[bindex(b)] |= (bitfield_t)(1 << boffset(b)); +} + +static inline void reset_bit(Bits bits, int b) +{ + bptr(bits)[bindex(b)] &= ~(1 << boffset(b)); +} + +static inline int get_bit(Bits bits, int b) +{ + int of = boffset(b); + return (bptr(bits)[bindex(b)] & (1 << of)) >> of; +} + +static inline Bits bits_copy(Bits dst, Bits src) +{ + if (dst->nw != src->nw) return 0; + return memcpy(&dst->bits, &src->bits, (sizeof(bitfield_t) * src->nw)); +} + +static void assert(int value, int expected, char*msg) +{ + if (value != expected) { + fprintf(stderr, "Error %s\n", msg); + exit(1); + } +} + +int main(int argc, char **argv, char **env) +{ + printf("bits in an bitfield_t : %d\n", BITFIELD_BITS); + Bits a = bits_alloc(33); + Bits b = bits_alloc(33); + set_bit(a, 31); + set_bit(a, 32); + set_bit(a, 33); + assert(get_bit(a, 30), 0, "bit 30 is not 0"); + assert(get_bit(a, 31), 1, "bit 31 is not 1"); + assert(get_bit(a, 32), 1, "bit 32 is not 1"); + assert(get_bit(a, 33), 1, "bit 33 is not 1"); + assert(get_bit(a, 34), 0, "bit 34 is not 0"); + reset_bit(a, 32); + assert(get_bit(a, 30), 0, "bit 30 is not 0"); + assert(get_bit(a, 31), 1, "bit 31 is not 1"); + assert(get_bit(a, 32), 0, "bit 32 is not 0"); + assert(get_bit(a, 33), 1, "bit 33 is not 1"); + assert(get_bit(a, 34), 0, "bit 34 is not 0"); + set_bit(a, 32); + reset_bit(a, 33); + reset_bit(a, 31); + assert(get_bit(a, 30), 0, "bit 30 is not 0"); + assert(get_bit(a, 31), 0, "bit 31 is not 0"); + assert(get_bit(a, 32), 1, "bit 32 is not 1"); + assert(get_bit(a, 33), 0, "bit 33 is not 0"); + assert(get_bit(a, 34), 0, "bit 34 is not 0"); + bits_copy(b, a); + assert(get_bit(b, 30), 0, "bit 30 is not 0"); + assert(get_bit(b, 31), 0, "bit 31 is not 0"); + assert(get_bit(b, 32), 1, "bit 32 is not 1"); + assert(get_bit(b, 33), 0, "bit 33 is not 0"); + assert(get_bit(b, 34), 0, "bit 34 is not 0"); + bits_free(a); + bits_free(b); + printf("Success\n"); + return 0; +} diff --git a/c/bit_compose.c b/c/bit_compose.c new file mode 100644 index 0000000..bd250db --- /dev/null +++ b/c/bit_compose.c @@ -0,0 +1,32 @@ +#include <stdint.h> +#include <stdio.h> + +typedef union __attribute__ ((__packed__)) +{ + struct __attribute__ ((__packed__)) + { + unsigned int table_id : 11; + unsigned int int_table_id : 11; + unsigned int entry_id : 12; + unsigned int generation : 30; + }; + uintptr_t i; +} BITS; + +uintptr_t compose(uintptr_t a, uintptr_t b, uintptr_t c, uintptr_t d) +{ + BITS i; + i.table_id = a; + i.int_table_id = b; + i.entry_id = c; + i.generation = d; + return i.i; +} + +int main(int argc, char **argv, char **env) +{ + uintptr_t t = compose(666,777,888,999); + printf("%d %d %d %d -> 0x%lu\n", 666, 777, 888, 999, t); + + return 0; +} @@ -0,0 +1,6 @@ +#! /bin/sh +for c in *.c +do + echo "############" && clang -pedantic -Wall -ldl $c -o ./bin && ./bin +done +rm ./bin diff --git a/c/malloc_hook.c b/c/malloc_hook.c new file mode 100644 index 0000000..aa22379 --- /dev/null +++ b/c/malloc_hook.c @@ -0,0 +1,37 @@ +#include <stdlib.h> +#include <stdio.h> + +#define __USE_GNU +#include <dlfcn.h> + +typedef void* (*real_malloc_t) (size_t); + +static real_malloc_t real_malloc = NULL; + +static void __mtrace_init(void) +{ + real_malloc = (real_malloc_t) dlsym(RTLD_NEXT, "malloc"); + if (NULL == real_malloc) { + fprintf(stderr, "Error in `dlsym`: %s\n", dlerror()); + return; + } +} + +void *malloc(size_t size) +{ + if(real_malloc == NULL) + __mtrace_init(); + + void *p = NULL; + fprintf(stderr, "malloc(%zu) = ", size); + p = real_malloc(size); + fprintf(stderr, "%p\n", p); + return p; +} + + +int main(int argc, char **argv, char **env) +{ + void * nothing = malloc(666); + free(nothing); +} |