Newbie - getting started

Question

Hi,
Hopefully someone can help me here.  I'm looking to place either simulated or camera raw output (and here I mean a matrix of 8 or 10 bit values without debayering) into a RAW format so that I can experiment with the debayering, white balance, colour profiles, linearization or LUTs that I need to shift my camera output into a useable image.  I was thinking about using the Adobe DNG format - but I'm struggling to understand where to start with this.
What I'd like to do to start with is simply create a DNG file with, say, a 10x10 image size, 8 bit data with a ramp profile: e.g.
0 20 40 60 80 100 120 140 160 180
0 20 40 60 80 100 120 140 160 180
0 20 40 60 80 100 120 140 160 180
I've been looking at using the dng_validate example and creating a new function:
static 
dng_error_code dng_createsim (const char *filenameOut){
After several attempts at this, I've sort of guessed that I need to access the data buffer in negative->Stage1Image(), but I've not succeeded in this.
Thanks for any help.
Simon

Answer 1

Following is the code I put together based on Sandy's comments.  I'm a bit sketchy on most of it, but it 'almost' compiles.  I'm a bit stuck with the raw_ifd part - I don't think I'm getting the idea about the dng_image.  I'm also unclear about defining the thumbnail - blank is fine with me.
Thanks,
Simon
static 
dng_error_code dng_createsim (const char *filename){
int sz=10;    // size of image 
dng_memory_allocator alloc(gDefaultDNGMemoryAllocator);
dng_host host;
dng_memory_block * mem_block = host.Allocate(sz*sz);
alloc=host.Allocator();
dng_memory_stream mem_stream(alloc);
mem_stream.SetWritePosition(0);
for (int i=0;i<sz;i++) 
  for (int j=0;j<sz;j++)    mem_stream.Put_uint8(j*sz);
//dng_rect rect(sz,sz);
dng_image Rimage();
dng_ifd rawifd;
rawifd.ReadImage(host,mem_stream,Rimage);
dng_negative *negative=host.Make_dng_negative();
dng_image_preview thumbnail;
dng_file_stream streamout(
"out.dng",true);dng_image_writer writer;
writer.WriteDNG(host,streamout,*negative,thumbnail);
return dng_error_none;}