libgloss/mips/cygmon.c

   1 /* cygmon.c -- Glue code for linking apps to run on top of Cygmon.
   2  *
   3  * Copyright (c) 1998, 1999, 2000 Red Hat, Inc.
   4  *
   5  * The authors hereby grant permission to use, copy, modify, distribute,
   6  * and license this software and its documentation for any purpose, provided
   7  * that existing copyright notices are retained in all copies and that this
   8  * notice is included verbatim in any distributions. No written agreement,
   9  * license, or royalty fee is required for any of the authorized uses.
  10  * Modifications to this software may be copyrighted by their authors
  11  * and need not follow the licensing terms described here, provided that
  12  * the new terms are clearly indicated on the first page of each file where
  13  * they apply.
  14  */
  15
  16 #include "syscall.h"
  17
  18 int
  19 write ( int file,
  20         char *buf,
  21         int nbytes)
  22 {
  23   return sysCall(SYS_write, file, (unsigned long)buf, nbytes);
  24 }
  25
  26 int
  27 read (int file,
  28       char *buf,
  29       int nbytes)
  30 {
  31   return sysCall(SYS_read, file, (unsigned long)buf, nbytes);
  32 }
  33
  34 int
  35 outbyte (unsigned char c)
  36 {
  37   return sysCall(SYS_write, 0, (unsigned long)&c, 1);
  38 }
  39
  40 unsigned char
  41 inbyte (void)
  42 {
  43   char c;
  44   sysCall(SYS_read, 0, (unsigned long)&c, 1);
  45   return c;
  46 }
  47
  48
  49 /* Structure filled in by get_mem_info.  Only the size field is
  50    actually used (by sbrk), so the others aren't even filled in.  */
  51 struct s_mem
  52 {
  53   unsigned int size;
  54   unsigned int icsize;
  55   unsigned int dcsize;
  56 };
  57
  58 // Perform a system call.
  59 // Unused parameters should be set to 0.
  60 int sysCall(unsigned long func, unsigned long p1, unsigned long p2, unsigned long p3)
  61 {
  62   int ret = 0;
  63   asm volatile ( "              \n\
  64           move $4, %1           \n\
  65           move $5, %2           \n\
  66           move $6, %3           \n\
  67           move $7, %4           \n\
  68           syscall               \n\
  69           nop                   \n\
  70           move %0, $2" : "=r"(ret) : "r"(func), "r"(p1), "r"(p2), "r"(p3));
  71   return ret;
  72 }
  73
  74 // These need to be kept in sync with the definitions in Cygmon.
  75 #define SYS_meminfo     1001
  76
  77 void *
  78 get_mem_info (mem)
  79      struct s_mem *mem;
  80 {
  81   unsigned long totmem = 0, topmem = 0;
  82   int numbanks;
  83
  84   numbanks = sysCall(SYS_meminfo, (unsigned long)&totmem, (unsigned long)&topmem, 0);
  85   mem->size = totmem;
  86   return (void*)topmem;
  87 }