DWIOBUFF *DwioBuffWrite( // WRITE A RECORD
DWIOBUFF *ctl, // - buffer control
void *record, // - record to be written
size_t size ) // - record size
{
DWIOBUFF *next; // - next buffer control
size_t len; // - amount to write
for(;;) {
len = DWBLOCK_BSIZE - ctl->current_offset;
if( len > size ) {
len = size;
}
memcpy( pointXfer( ctl ), record, len );
ctl->written = false;
ctl->current_offset += len;
record = (void *)((char *)record + len);
size -= len;
if( size == 0 )
break;
if( ctl->next_addr == 0 ) {
next = findWrBuffer();
ctl->next_addr = next->disk_addr;
next->prev_addr = ctl->disk_addr;
next->block_num = ctl->block_num + 1;
} else {
next = findReWrBuffer( ctl->next_addr );
}
next->current_offset = 0;
finishWrBuffer( ctl );
ctl = next;
}
return ctl;
}
DWIOBUFF *DwioBuffSeek( // POSITION TO SPECIFIED OFFSET FROM START
DWIOBUFF *ctl, // - current buffer control
DISK_ADDR block, // - starting disk address
size_t offset ) // - where to position to
{
DWIOBUFF *next; // - next buffer control
size_t required_block;
size_t required_offset;
required_block = offset / DWBLOCK_BSIZE;
required_offset = offset % DWBLOCK_BSIZE;
while( ctl->block_num != required_block ) {
if( ctl->block_num < required_block ) {
if( ctl->next_addr == 0 ) {
next = findWrBuffer();
ctl->next_addr = next->disk_addr;
next->prev_addr = ctl->disk_addr;
next->block_num = ctl->block_num + 1;
} else {
next = findReWrBuffer( ctl->next_addr );
}
} else {
if( (ctl->block_num - required_block) > required_block ) {
next = findReWrBuffer( block );
} else {
if( ctl->prev_addr == 0 ) {
#ifndef NDEBUG
CFatal( "dwiobuff: attempt to seek off start of file" );
#endif
} else {
next = findReWrBuffer( ctl->prev_addr );
}
}
}
finishWrBuffer( ctl );
ctl = next;
}
ctl->current_offset = required_offset;
return( ctl );
}
