bytebuffer.c

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/**********************************************************************
 *
 * PostGIS - Spatial Types for PostgreSQL
 * http://postgis.net
 *
 * PostGIS is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * PostGIS is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with PostGIS.  If not, see <http://www.gnu.org/licenses/>.
 *
 **********************************************************************
 *
 * Copyright 2015 Nicklas Avén <nicklas.aven@jordogskog.no>
 *
 **********************************************************************/



#include "liblwgeom_internal.h"
#include "bytebuffer.h"

bytebuffer_t*
bytebuffer_create(void)
{
        LWDEBUG(2,"Entered bytebuffer_create");
        return bytebuffer_create_with_size(BYTEBUFFER_STARTSIZE);
}

bytebuffer_t*
bytebuffer_create_with_size(size_t size)
{
        LWDEBUGF(2,"Entered bytebuffer_create_with_size %d", size);
        bytebuffer_t *s;

        s = lwalloc(sizeof(bytebuffer_t));
        if ( size < BYTEBUFFER_STATICSIZE )
        {
                s->capacity = BYTEBUFFER_STATICSIZE;
                s->buf_start = s->buf_static;
        }
        else
        {
                s->buf_start = lwalloc(size);
                s->capacity = size;
        }
        s->readcursor = s->writecursor = s->buf_start;
        memset(s->buf_start,0,s->capacity);
        LWDEBUGF(4,"We create a buffer on %p of %d bytes", s->buf_start, s->capacity);
        return s;
}

void
bytebuffer_init_with_size(bytebuffer_t *s, size_t size)
{
        if ( size < BYTEBUFFER_STATICSIZE )
        {
                s->capacity = BYTEBUFFER_STATICSIZE;
                s->buf_start = s->buf_static;
        }
        else
        {
                s->buf_start = lwalloc(size);
                s->capacity = size;
        }
        s->readcursor = s->writecursor = s->buf_start;
        memset(s->buf_start, 0, s->capacity);
}

void
bytebuffer_destroy(bytebuffer_t *s)
{
        bytebuffer_destroy_buffer(s);
        if ( s )
                lwfree(s);

        return;
}

void
bytebuffer_destroy_buffer(bytebuffer_t *s)
{
        if ( s->buf_start != s->buf_static )
        {
                lwfree(s->buf_start);
                s->buf_start = NULL;
        }

        return;
}

void
bytebuffer_reset_reading(bytebuffer_t *s)
{
        s->readcursor = s->buf_start;
}

void
bytebuffer_clear(bytebuffer_t *s)
{
        s->readcursor = s->writecursor = s->buf_start;
}

static inline void
bytebuffer_makeroom(bytebuffer_t *s, size_t size_to_add)
{
        LWDEBUGF(2,"Entered bytebuffer_makeroom with space need of %d", size_to_add);
        size_t current_write_size = (s->writecursor - s->buf_start);
        size_t current_read_size = (s->readcursor - s->buf_start);
        size_t capacity = s->capacity;
        size_t required_size = current_write_size + size_to_add;

        LWDEBUGF(2,"capacity = %d and required size = %d",capacity ,required_size);
        while (capacity < required_size)
                capacity *= 2;

        if ( capacity > s->capacity )
        {
                LWDEBUGF(4,"We need to realloc more memory. New capacity is %d", capacity);
                if ( s->buf_start == s->buf_static )
                {
                        s->buf_start = lwalloc(capacity);
                        memcpy(s->buf_start, s->buf_static, s->capacity);
                }
                else
                {
                        s->buf_start = lwrealloc(s->buf_start, capacity);
                }
                s->capacity = capacity;
                s->writecursor = s->buf_start + current_write_size;
                s->readcursor = s->buf_start + current_read_size;
        }
        return;
}

uint8_t*
bytebuffer_get_buffer_copy(const bytebuffer_t *s, size_t *buffer_length)
{
        size_t bufsz = bytebuffer_getlength(s);
        uint8_t *buf = lwalloc(bufsz);
        memcpy(buf, s->buf_start, bufsz);
        if ( buffer_length )
                *buffer_length = bufsz;
        return buf;
}

const uint8_t*
bytebuffer_get_buffer(const bytebuffer_t *s, size_t *buffer_length)
{
        if ( buffer_length )
                *buffer_length = bytebuffer_getlength(s);
        return s->buf_start;
}


void
bytebuffer_append_byte(bytebuffer_t *s, const uint8_t val)
{
        LWDEBUGF(2,"Entered bytebuffer_append_byte with value %d", val);
        bytebuffer_makeroom(s, 1);
        *(s->writecursor)=val;
        s->writecursor += 1;
        return;
}


void
bytebuffer_append_bulk(bytebuffer_t *s, void * start, size_t size)
{
        LWDEBUGF(2,"bytebuffer_append_bulk with size %d",size);
        bytebuffer_makeroom(s, size);
        memcpy(s->writecursor, start, size);
        s->writecursor += size;
        return;
}

void
bytebuffer_append_bytebuffer(bytebuffer_t *write_to,bytebuffer_t *write_from )
{
        LWDEBUG(2,"bytebuffer_append_bytebuffer");
        size_t size = bytebuffer_getlength(write_from);
        bytebuffer_makeroom(write_to, size);
        memcpy(write_to->writecursor, write_from->buf_start, size);
        write_to->writecursor += size;
        return;
}


void
bytebuffer_append_varint(bytebuffer_t *b, const int64_t val)
{
        size_t size;
        bytebuffer_makeroom(b, 16);
        size = varint_s64_encode_buf(val, b->writecursor);
        b->writecursor += size;
        return;
}

void
bytebuffer_append_uvarint(bytebuffer_t *b, const uint64_t val)
{
        size_t size;
        bytebuffer_makeroom(b, 16);
        size = varint_u64_encode_buf(val, b->writecursor);
        b->writecursor += size;
        return;
}


/*
* Writes Integer to the buffer
*/
void
bytebuffer_append_int(bytebuffer_t *buf, const int val, int swap)
{
        LWDEBUGF(2,"Entered bytebuffer_append_int with value %d, swap = %d", val, swap);

        LWDEBUGF(4,"buf_start = %p and write_cursor=%p", buf->buf_start,buf->writecursor);
        char *iptr = (char*)(&val);
        int i = 0;

        if ( sizeof(int) != WKB_INT_SIZE )
        {
                lwerror("Machine int size is not %d bytes!", WKB_INT_SIZE);
        }

        bytebuffer_makeroom(buf, WKB_INT_SIZE);
        /* Machine/request arch mismatch, so flip byte order */
        if ( swap)
        {
                LWDEBUG(4,"Ok, let's do the swaping thing");
                for ( i = 0; i < WKB_INT_SIZE; i++ )
                {
                        *(buf->writecursor) = iptr[WKB_INT_SIZE - 1 - i];
                        buf->writecursor += 1;
                }
        }
        /* If machine arch and requested arch match, don't flip byte order */
        else
        {
                LWDEBUG(4,"Ok, let's do the memcopying thing");
                memcpy(buf->writecursor, iptr, WKB_INT_SIZE);
                buf->writecursor += WKB_INT_SIZE;
        }

        LWDEBUGF(4,"buf_start = %p and write_cursor=%p", buf->buf_start,buf->writecursor);
        return;

}





void
bytebuffer_append_double(bytebuffer_t *buf, const double val, int swap)
{
        LWDEBUGF(2,"Entered bytebuffer_append_double with value %lf swap = %d", val, swap);

        LWDEBUGF(4,"buf_start = %p and write_cursor=%p", buf->buf_start,buf->writecursor);
        char *dptr = (char*)(&val);
        int i = 0;

        if ( sizeof(double) != WKB_DOUBLE_SIZE )
        {
                lwerror("Machine double size is not %d bytes!", WKB_DOUBLE_SIZE);
        }

        bytebuffer_makeroom(buf, WKB_DOUBLE_SIZE);

        /* Machine/request arch mismatch, so flip byte order */
        if ( swap )
        {
                LWDEBUG(4,"Ok, let's do the swapping thing");
                for ( i = 0; i < WKB_DOUBLE_SIZE; i++ )
                {
                        *(buf->writecursor) = dptr[WKB_DOUBLE_SIZE - 1 - i];
                        buf->writecursor += 1;
                }
        }
        /* If machine arch and requested arch match, don't flip byte order */
        else
        {
                LWDEBUG(4,"Ok, let's do the memcopying thing");
                memcpy(buf->writecursor, dptr, WKB_DOUBLE_SIZE);
                buf->writecursor += WKB_DOUBLE_SIZE;
        }

        LWDEBUG(4,"Return from bytebuffer_append_double");
        return;

}

int64_t
bytebuffer_read_varint(bytebuffer_t *b)
{
        size_t size;
        int64_t val = varint_s64_decode(b->readcursor, b->buf_start + b->capacity, &size);
        b->readcursor += size;
        return val;
}

uint64_t
bytebuffer_read_uvarint(bytebuffer_t *b)
{
        size_t size;
        uint64_t val = varint_u64_decode(b->readcursor, b->buf_start + b->capacity, &size);
        b->readcursor += size;
        return val;
}

size_t
bytebuffer_getlength(const bytebuffer_t *s)
{
        return (size_t) (s->writecursor - s->buf_start);
}


bytebuffer_t*
bytebuffer_merge(bytebuffer_t **buff_array, int nbuffers)
{
        size_t total_size = 0, current_size, acc_size = 0;
        int i;
        for ( i = 0; i < nbuffers; i++ )
        {
                total_size += bytebuffer_getlength(buff_array[i]);
        }

        bytebuffer_t *res = bytebuffer_create_with_size(total_size);
        for ( i = 0; i < nbuffers; i++)
        {
                current_size = bytebuffer_getlength(buff_array[i]);
                memcpy(res->buf_start+acc_size, buff_array[i]->buf_start, current_size);
                acc_size += current_size;
        }
        res->writecursor = res->buf_start + total_size;
        res->readcursor = res->buf_start;
        return res;
}