// Copyright status: this file is in the public domain.

#include <stdlib.h>
#include <strings.h>

#include "lx.h"

#include "proto.h"
#include "internal.h"

void lx_ChangeProperty(LX_CONN *xc, LX_XID window, LX_ATOM property, LX_ATOM type, int format, LX_PROPERTYMODE mode, const void *data, int len)
{
 int reqlen;
 unsigned char *req;
 int ushift;
 int proto_mode;
 int i;

 lx__nochain(xc);
 do <"badcall">
  { // 65535*4 is a conservative maximum which also ensures no arithmetic overflow below.
    if ((xc->flags & XCF_FAIL) || (len < 0) || (len > 65535*4)) break <"badcall">;
    proto_mode = lx__propertymode_to_proto(mode);
    if (proto_mode < 0) break <"badcall">;
    switch (format)
     { case  8: ushift = 0; break;
       case 16: ushift = 1; break;
       case 32: ushift = 2; break;
       default: break <"badcall">;
     }
    reqlen = 6 + (((len << ushift) + 3) >> 2);
    if (reqlen > 65535) break <"badcall">;
    req = malloc(reqlen<<2);
    if (! req)
     { lx__nomem_fail(xc);
       return;
     }
    req[0] = XP_REQ_ChangeProperty;
    req[1] = proto_mode;
    w_card16(&req[2],reqlen);
    w_card32(&req[4],window);
    w_card32(&req[8],property);
    w_card32(&req[12],type);
    req[16] = format;
    req[17] = 0; // unused
    req[18] = 0; // unused
    req[19] = 0; // unused
    w_card32(&req[20],len);
    switch (format)
     { case 8:
	  bcopy(data,req+24,len);
	  if (len & 3) bzero(req+24+len,4-(len&3)); // padding
	  break;
       case 16:
	  for (i=len-1;i>=0;i--) w_card16(req+24+(2*i),((const CARD16 *)data)[i]);
	  if (len & 1) w_card16(req+24+(2*len),0); // padding
	  break;
       case 32:
	  for (i=len-1;i>=0;i--) w_card32(req+24+(4*i),((const CARD32 *)data)[i]);
	  break;
       default:
	  lx_abort();
	  break;
     }
    lx__send_req(xc,&req[0],reqlen<<2);
    return;
  } while (0);
 lx__bad_call(xc,"lx_ChangeProperty");
}