asm {
  PUT_DEC_U64::
//RAX is number to print in decimal.
//Preserves all regs.
  PUSH  RBP
  MOV   RBP,RSP
  SUB   RSP,24          //24 char buffer on stack

//Save regs which C code is free to clobber.  We don't have to for C callers,
//but this function will be nice for ASM callers if it saves all regs.
  PUSH_C_REGS

  PUSH  RSI           //See REGG_LOCAL_VARS&REGG_LOCAL_NON_PTR_VARS
  LEA   RSI,-1[RBP]     //Load addr of end of buffer.
  //We picked RSI because of PUT_STR
  //We'll move bwd
  MOV   U8 [RSI],0      //Terminator

  TEST  RAX,RAX         //Special case -- zero
  JNZ   @@05
  DEC   RSI
  MOV   U8 [RSI],'0'
  JMP   @@15

@@05:   MOV     RBX,10          //Divides by 10

@@10:   XOR     RDX,RDX
  DIV   RBX             //RAX=(RDX:RAX)/RBX with remainder in RDX
  ADD   RDX,'0'
  DEC   RSI
  MOV   U8 [RSI],DL
  TEST  RAX,RAX
  JNZ   @@10

@@15:   CALL    PUT_STR
  POP   RSI
  POP_C_REGS
  LEAVE
  RET

  _DO_IT::      //The convention is C-callable routines have underscores.
  MOV   RAX,122333221
  CALL  PUT_DEC_U64
  MOV   RAX,'\n'
  CALL  PUT_CHARS
  RET
}

Call(_DO_IT);