feldspar_array.h

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#ifndef FELDSPAR_ARRAY_H
#define FELDSPAR_ARRAY_H

#include <stdint.h>
#include <string.h>
#include <assert.h>
#include <stdlib.h>
//#define LOG
#include "log.h"

#include <stdio.h> /* to be removed */

/* Important: Always zero-initialize struct arrays in the definitions
 * and call initArray on them before use:
 * 
 * struct array my = {0};
 * initArray( &my, sizeof(elementType), numberOfElements );
 * 
 * Zero initialization certifies that initArray works correctly.
 * (There is a "magic number" check in initArray in case you forget to
 * zero-initialize, but it is not 100% safe.)
 */

/* TODO qualify the names to avoid clashes with Haskell names */

struct array
{
    void*    buffer;   /* pointer to the buffer of elements */
    int32_t  length;   /* number of elements in the array */
    int32_t  elemSize; /* size of elements in bytes; (- sizeof(struct array)) for nested arrays */
    uint32_t bytes;    /* The number of bytes the buffer can hold */
    uint32_t inited;   /* To decide between first initialization and reinitialization - This is to catch */
};

/* Magic number */
#define INITED 0x89abcdef

/* Indexing into an array: */
/* Result: element of type 'type' */
#define at(type,arr,idx) (((type*)((arr)->buffer))[idx])

/* Array (re)initialization */
static inline void initArray(struct array *arr, int32_t size, int32_t len)
{
    int newBytes;

    log_3("initArray %p %d %d - enter\n", arr, size, len);
    assert(arr);
    arr->elemSize = size;
    arr->length = len;
    if( size < 0 )
        size = sizeof(struct array);
    newBytes = size * len;
    if( arr->buffer && (arr->inited == INITED) )
    {
        // Re-initialization
        log_1("initArray %p - reinitialize\n",arr);
        if( arr->bytes < newBytes )
        {
            log_3("initArray %p - realloc since %d < %d\n"
                 , arr, arr->bytes, newBytes);
            // Not enough space: reallocation needed
            arr->bytes = newBytes;
            free(arr->buffer);
            arr->buffer = (void*)malloc( newBytes );
        }
        else
        {
            // Otherwise: space is enough, nothing to do
            log_3("initArray %p - large enough %d >= %d\n"
                 , arr, arr->bytes, newBytes);
        }
    }
    else
    {
        // First initialization
        arr->bytes = newBytes;
        arr->buffer = (void*)malloc( newBytes );        
        log_5("initArray %p - alloc %d * %d bytes %d at %p\n"
             , arr, arr->length, arr->elemSize, newBytes, arr->buffer);
        arr->inited = INITED;
    }
    assert( arr->buffer );
    log_3("initArray %p %d %d - leave\n", arr, size, len);
}

// Free array
// TODO: Think about arrays escaping from their scope.
static inline void freeArray(struct array *arr)
{
    log_1("freeArray %p - enter\n", arr);
    // assert(arr);
    // if( !arr->buffer || arr->inited != INITED )
    // {
        // return;
    // }
    // if( arr->elemSize < 0 )
    // {
        // int i;
        // for( i=0; i<arr->length; ++i )
            // freeArray( &at(struct array,arr,i) );
    // }
    // free(arr->buffer);
    // For the sake of extra safety:
    // arr->buffer = 0;
    // arr->length = 0;
    // arr->bytes = 0;
    // arr->inited = 0;
    log_1("freeArray %p - leave\n", arr);
}

/* Deep array copy */
static inline void copyArray(struct array *to, struct array *from)
{
    assert(to);
    assert(from);
    log_2("copyArray %p %p - enter\n", to, from);
    if( from->elemSize < 0 )
    {
        log_2("copyArray %p %p - nested enter\n", to, from);
        unsigned i;
        for( i = 0; i < from->length; ++i )
        {
            struct array *to_row = &at(struct array, to, i);
            struct array *from_row = &at(struct array, from, i);
            if( !to_row->buffer || to_row->inited != INITED )
                initArray( to_row, from_row->elemSize, from_row->length );
            copyArray( to_row, from_row );
        }
        log_2("copyArray %p %p - nested leave\n", to, from);
    }
    else
    {
        assert(to->buffer);
        assert(from->buffer);
        log_3("copyArray %p %p - memcpy %d bytes\n", to, from
            , from->length * from->elemSize);
        memcpy( to->buffer, from->buffer, from->length * from->elemSize );
    }
    log_2("copyArray %p %p - leave\n", to, from);
}

/* Deep array copy to a given position */
static inline void copyArrayPos(struct array *to, unsigned pos, struct array *from)
{
    assert(to);
    assert(from);
    log_3("copyArrayPos %p %d %p - enter\n", to, pos, from);
    if( from->elemSize < 0 )
    {
        unsigned i;
        for( i = 0; i < from->length; ++i )
            copyArray( &at(struct array, to, i + pos), &at(struct array, from, i) );
    }
    else
    {
        assert(to->buffer);
        assert(from->buffer);
        memcpy( (char*)(to->buffer) + pos * to->elemSize, from->buffer, from->length * from->elemSize );
    }
    log_3("copyArrayPos %p %d %p - leave\n", to, pos, from);
}


/* Deep array copy with a given length */
void copyArrayLen(struct array *to, struct array *from, int32_t len);

/* Array length */
static inline int32_t getLength(struct array *arr)
{
  assert(arr);
  return arr->length;
}

/* Reset array length */
static inline void setLength(struct array *arr, int32_t len)
{
    assert(arr);
    log_2("setLength %p %d - enter\n", arr, len);
    int newBytes = arr->elemSize * len;
    if( arr->bytes >= newBytes )
    {
        arr->length = len;
    }
    else
    {
        log_3("setLength %p %d - realloc %d bytes\n", arr, len, newBytes);
        // TODO: copy
        arr->bytes = newBytes;
        free( arr->buffer );
        arr->buffer = malloc( newBytes );
        assert( arr->buffer );
    }
    log_2("setLength %p %d - leave\n", arr, len);
}

#endif