File : g-io-put-leon3.adb


   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --                          G N A T . I O . P U T                           --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --                       Copyright (C) 2012, AdaCore                        --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  17 --                                                                          --
  18 --                                                                          --
  19 --                                                                          --
  20 --                                                                          --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNAT was originally developed  by the GNAT team at  New York University. --
  28 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31 
  32 --  LEON3 version of text output routine
  33 
  34 with System;
  35 
  36 separate (GNAT.IO)
  37 procedure Put (C : Character) is
  38 
  39    --  Minimal version of output routine to output to a APBUART device. A
  40    --  description of the UART is in the GRLIB IP Core User’s Manual. The
  41    --  address is hardcoded based on default template designs and the default
  42    --  configuration of various simulators.
  43 
  44    type Register is mod 2**32;
  45 
  46    UART_Address : constant := 16#8000_0100#;
  47 
  48    UART_Data    : Register; --  Write this register to transmit data
  49    UART_Status  : Register; --  Check this register for transmitter status
  50 
  51    for UART_Data'Address   use System'To_Address (UART_Address + 0);
  52    for UART_Status'Address use System'To_Address (UART_Address + 4);
  53 
  54    pragma Volatile (UART_Data);
  55    pragma Volatile (UART_Status);
  56 
  57    Transmitter_Empty_Bit : constant Register := 2**2;
  58    --  When this bit is set, another character can be queued for transmission
  59 
  60 begin
  61    --  Busy-wait while the transmitter register is not empty
  62 
  63    while (UART_Status and Transmitter_Empty_Bit) = 0 loop
  64       null;
  65    end loop;
  66 
  67    UART_Data := Character'Pos (C);
  68 end Put;