core/legacynet/portnum.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2010 Intel Corporation; author: H. Peter Anvin
   4  *
   5  *   This program is free software; you can redistribute it and/or modify
   6  *   it under the terms of the GNU General Public License as published by
   7  *   the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
   8  *   Boston MA 02110-1301, USA; either version 2 of the License, or
   9  *   (at your option) any later version; incorporated herein by reference.
  10  *
  11  * ----------------------------------------------------------------------- */
  12
  13 #include <stdint.h>
  14 #include <stdbool.h>
  15 #include <netinet/in.h>
  16 #include "pxe.h"
  17
  18 /* Port number bitmap - port numbers 49152 (0xc000) to 57343 (0xefff) */
  19 #define PORT_NUMBER_BASE        49152
  20 #define PORT_NUMBER_COUNT       8192 /* Power of 2, please */
  21 static uint32_t port_number_bitmap[PORT_NUMBER_COUNT/32];
  22 static uint16_t first_port_number /* = 0 */;
  23
  24 /*
  25  * Bitmap functions
  26  */
  27 static bool test_bit(const uint32_t *bitmap, int32_t index)
  28 {
  29     uint8_t st;
  30     asm("btl %2,%1 ; setc %0" : "=qm" (st) : "m" (*bitmap), "r" (index));
  31     return st;
  32 }
  33
  34 static void set_bit(uint32_t *bitmap, int32_t index)
  35 {
  36     asm volatile("btsl %1,%0" : "+m" (*bitmap) : "r" (index) : "memory");
  37 }
  38
  39 static void clr_bit(uint32_t *bitmap, int32_t index)
  40 {
  41     asm volatile("btcl %1,%0" : "+m" (*bitmap) : "r" (index) : "memory");
  42 }
  43
  44 /*
  45  * Get and free a port number (host byte order)
  46  */
  47 uint16_t get_port(void)
  48 {
  49     uint16_t port;
  50
  51     do {
  52         port = first_port_number++;
  53         first_port_number &= PORT_NUMBER_COUNT - 1;
  54     } while (test_bit(port_number_bitmap, port));
  55
  56     set_bit(port_number_bitmap, port);
  57     return htons(port + PORT_NUMBER_BASE);
  58 }
  59
  60 void free_port(uint16_t port)
  61 {
  62     port = ntohs(port) - PORT_NUMBER_BASE;
  63
  64     if (port >= PORT_NUMBER_COUNT)
  65         return;
  66
  67     clr_bit(port_number_bitmap, port);
  68 }