ucx: ucx/stack.c@b7d1317b138e

     1 /*

     2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

     3  *

     4  * Copyright 2017 Olaf Wintermann. All rights reserved.

     5  *

     6  * Redistribution and use in source and binary forms, with or without

     7  * modification, are permitted provided that the following conditions are met:

     8  *

     9  *   1. Redistributions of source code must retain the above copyright

    10  *      notice, this list of conditions and the following disclaimer.

    11  *

    12  *   2. Redistributions in binary form must reproduce the above copyright

    13  *      notice, this list of conditions and the following disclaimer in the

    14  *      documentation and/or other materials provided with the distribution.

    15  *

    16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

    17  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

    18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

    19  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE

    20  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

    21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

    22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

    23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

    24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

    25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

    26  * POSSIBILITY OF SUCH DAMAGE.

    27  */

    29 #include "stack.h"

    30 #include <string.h>

    32 static size_t ucx_stack_align(size_t n) {

    33     int align = n % sizeof(void*);

    34     if (align) {

    35         n += sizeof(void*) - align;

    36     }

    37     return n;

    38 }

    40 void ucx_stack_init(UcxStack *stack, char* space, size_t size) {

    41     stack->size = size - size % sizeof(void*);

    42     stack->space = space;

    43     stack->top = NULL;

    45     stack->allocator.pool = stack;

    46     stack->allocator.malloc = (ucx_allocator_malloc) ucx_stack_malloc;

    47     stack->allocator.calloc = (ucx_allocator_calloc) ucx_stack_calloc;

    48     stack->allocator.realloc = (ucx_allocator_realloc) ucx_stack_realloc;

    49     stack->allocator.free = (ucx_allocator_free) ucx_stack_free;

    50 }

    52 void *ucx_stack_malloc(UcxStack *stack, size_t n) {

    54     if (ucx_stack_avail(stack) < ucx_stack_align(n)) {

    55         return NULL;

    56     } else {

    57         char *prev = stack->top;

    58         if (stack->top) {

    59             stack->top += ucx_stack_align(ucx_stack_topsize(stack));

    60         } else {

    61             stack->top = stack->space;

    62         }

    64         ((struct ucx_stack_metadata*)stack->top)->prev = prev;

    65         ((struct ucx_stack_metadata*)stack->top)->size = n;

    66         stack->top += sizeof(struct ucx_stack_metadata);

    68         return stack->top;

    69     }

    70 }

    72 void *ucx_stack_calloc(UcxStack *stack, size_t nelem, size_t elsize) {

    73     void *mem = ucx_stack_malloc(stack, nelem*elsize);

    74     memset(mem, 0, nelem*elsize);

    75     return mem;

    76 }

    78 void *ucx_stack_realloc(UcxStack *stack, void *ptr, size_t n) {

    79     if (ptr == stack->top) {

    80         if (stack->size - (stack->top - stack->space) < ucx_stack_align(n)) {

    81             return NULL;

    82         } else {

    83             ((struct ucx_stack_metadata*)stack->top - 1)->size = n;

    84             return ptr;

    85         }

    86     } else {

    87         if (ucx_stack_align(((struct ucx_stack_metadata*)ptr - 1)->size) <

    88                 ucx_stack_align(n)) {

    89             void *nptr = ucx_stack_malloc(stack, n);

    90             if (nptr) {

    91                 memcpy(nptr, ptr, n);

    92                 ucx_stack_free(stack, ptr);

    94                 return nptr;

    95             } else {

    96                 return NULL;

    97             }

    98         } else {

    99             ((struct ucx_stack_metadata*)ptr - 1)->size = n;

   100             return ptr;

   101         }

   102     }

   103 }

   105 void ucx_stack_free(UcxStack *stack, void *ptr) {

   106     if (ptr == stack->top) {

   107         stack->top = ((struct ucx_stack_metadata*) stack->top - 1)->prev;

   108     } else {

   109         struct ucx_stack_metadata *next = (struct ucx_stack_metadata*)(

   110             (char*)ptr +

   111             ucx_stack_align(((struct ucx_stack_metadata*) ptr - 1)->size)

   112         );

   113         next->prev = ((struct ucx_stack_metadata*) ptr - 1)->prev;

   114     }

   115 }

   117 void ucx_stack_popn(UcxStack *stack, void *dest, size_t n) {

   118     if (ucx_stack_empty(stack)) {

   119         return;

   120     }

   122     size_t len = ucx_stack_topsize(stack);

   123     if (len > n) {

   124         len = n;

   125     }

   127     memcpy(dest, stack->top, len);

   129     ucx_stack_free(stack, stack->top);

   130 }

   132 size_t ucx_stack_avail(UcxStack *stack) {

   133     size_t avail = ((stack->top ? (stack->size

   134                     - (stack->top - stack->space)

   135                     - ucx_stack_align(ucx_stack_topsize(stack)))

   136                     : stack->size));

   138     if (avail > sizeof(struct ucx_stack_metadata)) {

   139         return avail - sizeof(struct ucx_stack_metadata);

   140     } else {

   141         return 0;

   142     }

   143 }

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