memory_pad.c

#include <stdlib.h>

#   define sys_malloc  malloc
#   define sys_realloc realloc
#   define sys_free    free

#   define sys_memset  memset
#   define sys_memmove memmove

#   define sys_scope_begin do {
#   define sys_scope_end   } while (0)

#   define sys_cast(_Tp, __var) (_Tp)__var

#   define sys_bsize(__n_item, __s_item) \
   ((sys_cast(const size_t, (__n_item))) * (sys_cast(const size_t, (__s_item))))

#   define sys_cksize(__n) \
   ((__n) > 0 && sys_cast(const size_t, (__n)) <  sys_cast(const size_t, (1024 * 16)))

#   define sys_ckaddr(__addr_ptr) \
   (((__addr_ptr) != NULL) ? 1 : 0)

#   define sys_cknull(__addr_ptr) \
   (((__addr_ptr) == NULL) ? 1 : 0)

#   define sys_dealloc(__addr_ptr)  \
   sys_scope_begin                  \
      if (sys_ckaddr(__addr_ptr)) { \
         sys_free(__addr_ptr);      \
         (__addr_ptr) = NULL;       \
      }                             \
   sys_scope_end

#   define sys_realloc_type(_Tp, __addr_ptr, __n_item)                              \
      sys_scope_begin                                                               \
         size_t __n_size    = sys_bsize(__n_item, sizeof(_Tp));                     \
         _Tp * __addr       = NULL;                                                 \
         if (sys_cknull(__addr_ptr) && sys_cksize(__n_size)) {                      \
            __addr          = sys_cast(_Tp *, sys_malloc(__n_size));                \
            (__addr_ptr)    = __addr;                                               \
         } else if (sys_ckaddr(__addr_ptr)) && sys_cksize(__n_size)) {              \
            __addr          = sys_cast(_Tp *, sys_realloc((__addr_ptr), __n_size)); \
            if (sys_cknull(__addr)) {                                               \
               sys_dealloc((__addr_ptr));                                           \
            } else {                                                                \
               (__addr_ptr) = __addr;                                               \
            }                                                                       \
         } else {                                                                   \
            sys_dealloc(__addr_ptr);                                                \
         }                                                                          \
      sys_scope_end

#   define sys_pad_left_type(_Tp, __addr_ptr, __n_item, __n_pad, __v_pad)                            \
      sys_scope_begin                                                                                \
         sys_realloc_type(_Tp, (__addr_ptr), sys_bsize((__n_item) + (__n_pad), sizeof(_Tp)));        \
         if (sys_ckaddr(__addr_ptr)) {                                                               \
            sys_memmove((__addr_ptr) + (__n_pad), (__addr_ptr), sys_bsize((__n_item), sizeof(_Tp))); \
            sys_memset((__addr_ptr), (__v_pad), sys_bsize((__n_pad), sizeof(_Tp)));                  \
         }                                                                                           \
      sys_scope_end

#   define sys_pad_right_type(_Tp, __addr_ptr, __n_item, __n_pad, __v_pad)                           \
      sys_scope_begin                                                                                \
         sys_realloc_type(_Tp, (__addr_ptr), sys_bsize((__n_item) + (__n_pad), sizeof(_Tp)));        \
         if (sys_ckaddr(__addr_ptr)) {                                                               \
            sys_memset((__addr_ptr) + (__n_item), (__v_pad), sys_bsize((__n_pad), sizeof(_Tp)));     \
         }                                                                                           \
      sys_scope_end

/* EOF */