arch/i386/math-emu/fpu_aux.c

   1 /*---------------------------------------------------------------------------+
   2  |  fpu_aux.c                                                                |
   3  |                                                                           |
   4  | Code to implement some of the FPU auxiliary instructions.                 |
   5  |                                                                           |
   6  | Copyright (C) 1992,1993,1994,1997                                         |
   7  |                  W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
   8  |                  E-mail   billm@suburbia.net                              |
   9  |                                                                           |
  10  |                                                                           |
  11  +---------------------------------------------------------------------------*/
  12
  13 #include "fpu_system.h"
  14 #include "exception.h"
  15 #include "fpu_emu.h"
  16 #include "status_w.h"
  17 #include "control_w.h"
  18
  19
  20 static void fnop(void)
  21 {
  22 }
  23
  24 static void fclex(void)
  25 {
  26   partial_status &= ~(SW_Backward|SW_Summary|SW_Stack_Fault|SW_Precision|
  27                    SW_Underflow|SW_Overflow|SW_Zero_Div|SW_Denorm_Op|
  28                    SW_Invalid);
  29   no_ip_update = 1;
  30 }
  31
  32 /* Needs to be externally visible */
  33 void finit(void)
  34 {
  35   control_word = 0x037f;
  36   partial_status = 0;
  37   top = 0;            /* We don't keep top in the status word internally. */
  38   fpu_tag_word = 0xffff;
  39   /* The behaviour is different from that detailed in
  40      Section 15.1.6 of the Intel manual */
  41   operand_address.offset = 0;
  42   operand_address.selector = 0;
  43   instruction_address.offset = 0;
  44   instruction_address.selector = 0;
  45   instruction_address.opcode = 0;
  46   no_ip_update = 1;
  47 }
  48
  49 /*
  50  * These are nops on the i387..
  51  */
  52 #define feni fnop
  53 #define fdisi fnop
  54 #define fsetpm fnop
  55
  56 static FUNC const finit_table[] = {
  57   feni, fdisi, fclex, finit,
  58   fsetpm, FPU_illegal, FPU_illegal, FPU_illegal
  59 };
  60
  61 void finit_(void)
  62 {
  63   (finit_table[FPU_rm])();
  64 }
  65
  66
  67 static void fstsw_ax(void)
  68 {
  69   *(short *) &FPU_EAX = status_word();
  70   no_ip_update = 1;
  71 }
  72
  73 static FUNC const fstsw_table[] = {
  74   fstsw_ax, FPU_illegal, FPU_illegal, FPU_illegal,
  75   FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal
  76 };
  77
  78 void fstsw_(void)
  79 {
  80   (fstsw_table[FPU_rm])();
  81 }
  82
  83
  84 static FUNC const fp_nop_table[] = {
  85   fnop, FPU_illegal, FPU_illegal, FPU_illegal,
  86   FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal
  87 };
  88
  89 void fp_nop(void)
  90 {
  91   (fp_nop_table[FPU_rm])();
  92 }
  93
  94
  95 void fld_i_(void)
  96 {
  97   FPU_REG *st_new_ptr;
  98   int i;
  99   u_char tag;
 100
 101   if ( STACK_OVERFLOW )
 102     { FPU_stack_overflow(); return; }
 103
 104   /* fld st(i) */
 105   i = FPU_rm;
 106   if ( NOT_EMPTY(i) )
 107     {
 108       reg_copy(&st(i), st_new_ptr);
 109       tag = FPU_gettagi(i);
 110       push();
 111       FPU_settag0(tag);
 112     }
 113   else
 114     {
 115       if ( control_word & CW_Invalid )
 116         {
 117           /* The masked response */
 118           FPU_stack_underflow();
 119         }
 120       else
 121         EXCEPTION(EX_StackUnder);
 122     }
 123
 124 }
 125
 126
 127 void fxch_i(void)
 128 {
 129   /* fxch st(i) */
 130   FPU_REG t;
 131   int i = FPU_rm;
 132   FPU_REG *st0_ptr = &st(0), *sti_ptr = &st(i);
 133   long tag_word = fpu_tag_word;
 134   int regnr = top & 7, regnri = ((regnr + i) & 7);
 135   u_char st0_tag = (tag_word >> (regnr*2)) & 3;
 136   u_char sti_tag = (tag_word >> (regnri*2)) & 3;
 137
 138   if ( st0_tag == TAG_Empty )
 139     {
 140       if ( sti_tag == TAG_Empty )
 141         {
 142           FPU_stack_underflow();
 143           FPU_stack_underflow_i(i);
 144           return;
 145         }
 146       if ( control_word & CW_Invalid )
 147         {
 148           /* Masked response */
 149           FPU_copy_to_reg0(sti_ptr, sti_tag);
 150         }
 151       FPU_stack_underflow_i(i);
 152       return;
 153     }
 154   if ( sti_tag == TAG_Empty )
 155     {
 156       if ( control_word & CW_Invalid )
 157         {
 158           /* Masked response */
 159           FPU_copy_to_regi(st0_ptr, st0_tag, i);
 160         }
 161       FPU_stack_underflow();
 162       return;
 163     }
 164   clear_C1();
 165
 166   reg_copy(st0_ptr, &t);
 167   reg_copy(sti_ptr, st0_ptr);
 168   reg_copy(&t, sti_ptr);
 169
 170   tag_word &= ~(3 << (regnr*2)) & ~(3 << (regnri*2));
 171   tag_word |= (sti_tag << (regnr*2)) | (st0_tag << (regnri*2));
 172   fpu_tag_word = tag_word;
 173 }
 174
 175
 176 void ffree_(void)
 177 {
 178   /* ffree st(i) */
 179   FPU_settagi(FPU_rm, TAG_Empty);
 180 }
 181
 182
 183 void ffreep(void)
 184 {
 185   /* ffree st(i) + pop - unofficial code */
 186   FPU_settagi(FPU_rm, TAG_Empty);
 187   FPU_pop();
 188 }
 189
 190
 191 void fst_i_(void)
 192 {
 193   /* fst st(i) */
 194   FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);
 195 }
 196
 197
 198 void fstp_i(void)
 199 {
 200   /* fstp st(i) */
 201   FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);
 202   FPU_pop();
 203 }
 204