root/include/asm-m68k/system.h

/* */

INCLUDED FROM

DEFINITIONS

1. rdusp
2. wrusp
3. __xchg
4. __xchg

   1 #ifndef _M68K_SYSTEM_H
   2 #define _M68K_SYSTEM_H
   3 
   4 #include <linux/config.h> /* get configuration macros */
   5 #include <linux/linkage.h>
   6 #include <asm/segment.h>
   7 
   8 extern inline unsigned long rdusp(void) {
     /*  */
   9         unsigned long usp;
  10 
  11         __asm__ __volatile__("movec %/usp,%0"
  12                              : "=d" (usp));
  13         return usp;
  14 }
  15 
  16 extern inline void wrusp(unsigned long usp) {
     /*  */
  17         __asm__ __volatile__("movec %0,%/usp"
  18                              :
  19                              : "d" (usp));
  20 }
  21 
  22 /*
  23  * switch_to(n) should switch tasks to task ptr, first checking that
  24  * ptr isn't the current task, in which case it does nothing.  This
  25  * also clears the TS-flag if the task we switched to has used the
  26  * math co-processor latest.
  27  */
  28 /*
  29  * switch_to() saves the extra registers, that are not saved
  30  * automatically by SAVE_SWITCH_STACK in resume(), ie. d0-d5 and
  31  * a0-a1. Some of these are used by schedule() and its predecessors
  32  * and so we might get see unexpected behaviors when a task returns
  33  * with unexpected register values.
  34  *
  35  * syscall stores these regsiters itself and none of them are used
  36  * by syscall after the function in the syscall has been called.
  37  *
  38  * Beware that resume now expects *next to be in d1 and the offset of
  39  * tss to be in a1. This saves a few instructions as we no longer have
  40  * to push them onto the stack and read them back right after.
  41  *
  42  * 02/17/96 - Jes Sorensen (jds@kom.auc.dk)
  43  */
  44 asmlinkage void resume(void);
  45 #define switch_to(prev,next) { \
  46   register int k __asm__ ("a1") = (int)&((struct task_struct *)0)->tss; \
  47   register int n __asm__ ("d1") = (int)next; \
  48   __asm__ __volatile__("jbsr " SYMBOL_NAME_STR(resume) "\n\t" \
  49                        : : "a" (k), "d" (n) \
  50                        : "d0", "d1", "d2", "d3", "d4", "d5", "a0", "a1"); \
  51 }
  52 
  53 #define xchg(ptr,x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
  54 #define tas(ptr) (xchg((ptr),1))
  55 
  56 struct __xchg_dummy { unsigned long a[100]; };
  57 #define __xg(x) ((volatile struct __xchg_dummy *)(x))
  58 
  59 #if defined(CONFIG_ATARI) && !defined(CONFIG_AMIGA) && !defined(CONFIG_MAC)
  60 /* block out HSYNC on the atari */
  61 #define sti() __asm__ __volatile__ ("andiw #0xfbff,%/sr": : : "memory")
  62 #else /* portable version */
  63 #define sti() __asm__ __volatile__ ("andiw #0xf8ff,%/sr": : : "memory")
  64 #endif /* machine compilation types */ 
  65 #define cli() __asm__ __volatile__ ("oriw  #0x0700,%/sr": : : "memory")
  66 #define nop() __asm__ __volatile__ ("nop"::)
  67 
  68 #define save_flags(x) \
  69 __asm__ __volatile__("movew %/sr,%0":"=d" (x) : /* no input */ :"memory")
  70 
  71 #define restore_flags(x) \
  72 __asm__ __volatile__("movew %0,%/sr": /* no outputs */ :"d" (x) : "memory")
  73 
  74 #define iret() __asm__ __volatile__ ("rte": : :"memory", "sp", "cc")
  75 
  76 #if 1
  77 static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
     /*  */
  78 {
  79   unsigned long tmp, flags;
  80 
  81   save_flags(flags);
  82   cli();
  83 
  84   switch (size) {
  85   case 1:
  86     __asm__ __volatile__
  87     ("moveb %2,%0\n\t"
  88      "moveb %1,%2"
  89     : "=&d" (tmp) : "d" (x), "m" (*__xg(ptr)) : "memory");
  90     break;
  91   case 2:
  92     __asm__ __volatile__
  93     ("movew %2,%0\n\t"
  94      "movew %1,%2"
  95     : "=&d" (tmp) : "d" (x), "m" (*__xg(ptr)) : "memory");
  96     break;
  97   case 4:
  98     __asm__ __volatile__
  99     ("movel %2,%0\n\t"
 100      "movel %1,%2"
 101     : "=&d" (tmp) : "d" (x), "m" (*__xg(ptr)) : "memory");
 102     break;
 103   }
 104   restore_flags(flags);
 105   return tmp;
 106 }
 107 #else
 108 static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
     /*  */
 109 {
 110         switch (size) {
 111             case 1:
 112                 __asm__ __volatile__
 113                         ("moveb %2,%0\n\t"
 114                          "1:\n\t"
 115                          "casb %0,%1,%2\n\t"
 116                          "jne 1b"
 117                          : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
 118                 break;
 119             case 2:
 120                 __asm__ __volatile__
 121                         ("movew %2,%0\n\t"
 122                          "1:\n\t"
 123                          "casw %0,%1,%2\n\t"
 124                          "jne 1b"
 125                          : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
 126                 break;
 127             case 4:
 128                 __asm__ __volatile__
 129                         ("movel %2,%0\n\t"
 130                          "1:\n\t"
 131                          "casl %0,%1,%2\n\t"
 132                          "jne 1b"
 133                          : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
 134                 break;
 135         }
 136         return x;
 137 }
 138 #endif
 139 
 140 #endif /* _M68K_SYSTEM_H */

/* */