arch/x86/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 static void fnop(void)
  20 {
  21 }
  22
  23 static void fclex(void)
  24 {
  25         partial_status &=
  26             ~(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_soft_fpu(struct i387_soft_struct *soft)
  34 {
  35         struct address *oaddr, *iaddr;
  36         memset(soft, 0, sizeof(*soft));
  37         soft->cwd = 0x037f;
  38         soft->swd = 0;
  39         soft->ftop = 0; /* We don't keep top in the status word internally. */
  40         soft->twd = 0xffff;
  41         /* The behaviour is different from that detailed in
  42            Section 15.1.6 of the Intel manual */
  43         oaddr = (struct address *)&soft->foo;
  44         oaddr->offset = 0;
  45         oaddr->selector = 0;
  46         iaddr = (struct address *)&soft->fip;
  47         iaddr->offset = 0;
  48         iaddr->selector = 0;
  49         iaddr->opcode = 0;
  50         soft->no_update = 1;
  51 }
  52
  53 void finit(void)
  54 {
  55         finit_soft_fpu(&current->thread.fpu.state->soft);
  56 }
  57
  58 /*
  59  * These are nops on the i387..
  60  */
  61 #define feni fnop
  62 #define fdisi fnop
  63 #define fsetpm fnop
  64
  65 static FUNC const finit_table[] = {
  66         feni, fdisi, fclex, finit,
  67         fsetpm, FPU_illegal, FPU_illegal, FPU_illegal
  68 };
  69
  70 void finit_(void)
  71 {
  72         (finit_table[FPU_rm]) ();
  73 }
  74
  75 static void fstsw_ax(void)
  76 {
  77         *(short *)&FPU_EAX = status_word();
  78         no_ip_update = 1;
  79 }
  80
  81 static FUNC const fstsw_table[] = {
  82         fstsw_ax, FPU_illegal, FPU_illegal, FPU_illegal,
  83         FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal
  84 };
  85
  86 void fstsw_(void)
  87 {
  88         (fstsw_table[FPU_rm]) ();
  89 }
  90
  91 static FUNC const fp_nop_table[] = {
  92         fnop, FPU_illegal, FPU_illegal, FPU_illegal,
  93         FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal
  94 };
  95
  96 void fp_nop(void)
  97 {
  98         (fp_nop_table[FPU_rm]) ();
  99 }
 100
 101 void fld_i_(void)
 102 {
 103         FPU_REG *st_new_ptr;
 104         int i;
 105         u_char tag;
 106
 107         if (STACK_OVERFLOW) {
 108                 FPU_stack_overflow();
 109                 return;
 110         }
 111
 112         /* fld st(i) */
 113         i = FPU_rm;
 114         if (NOT_EMPTY(i)) {
 115                 reg_copy(&st(i), st_new_ptr);
 116                 tag = FPU_gettagi(i);
 117                 push();
 118                 FPU_settag0(tag);
 119         } else {
 120                 if (control_word & CW_Invalid) {
 121                         /* The masked response */
 122                         FPU_stack_underflow();
 123                 } else
 124                         EXCEPTION(EX_StackUnder);
 125         }
 126
 127 }
 128
 129 void fxch_i(void)
 130 {
 131         /* fxch st(i) */
 132         FPU_REG t;
 133         int i = FPU_rm;
 134         FPU_REG *st0_ptr = &st(0), *sti_ptr = &st(i);
 135         long tag_word = fpu_tag_word;
 136         int regnr = top & 7, regnri = ((regnr + i) & 7);
 137         u_char st0_tag = (tag_word >> (regnr * 2)) & 3;
 138         u_char sti_tag = (tag_word >> (regnri * 2)) & 3;
 139
 140         if (st0_tag == TAG_Empty) {
 141                 if (sti_tag == TAG_Empty) {
 142                         FPU_stack_underflow();
 143                         FPU_stack_underflow_i(i);
 144                         return;
 145                 }
 146                 if (control_word & CW_Invalid) {
 147                         /* Masked response */
 148                         FPU_copy_to_reg0(sti_ptr, sti_tag);
 149                 }
 150                 FPU_stack_underflow_i(i);
 151                 return;
 152         }
 153         if (sti_tag == TAG_Empty) {
 154                 if (control_word & CW_Invalid) {
 155                         /* Masked response */
 156                         FPU_copy_to_regi(st0_ptr, st0_tag, i);
 157                 }
 158                 FPU_stack_underflow();
 159                 return;
 160         }
 161         clear_C1();
 162
 163         reg_copy(st0_ptr, &t);
 164         reg_copy(sti_ptr, st0_ptr);
 165         reg_copy(&t, sti_ptr);
 166
 167         tag_word &= ~(3 << (regnr * 2)) & ~(3 << (regnri * 2));
 168         tag_word |= (sti_tag << (regnr * 2)) | (st0_tag << (regnri * 2));
 169         fpu_tag_word = tag_word;
 170 }
 171
 172 void ffree_(void)
 173 {
 174         /* ffree st(i) */
 175         FPU_settagi(FPU_rm, TAG_Empty);
 176 }
 177
 178 void ffreep(void)
 179 {
 180         /* ffree st(i) + pop - unofficial code */
 181         FPU_settagi(FPU_rm, TAG_Empty);
 182         FPU_pop();
 183 }
 184
 185 void fst_i_(void)
 186 {
 187         /* fst st(i) */
 188         FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);
 189 }
 190
 191 void fstp_i(void)
 192 {
 193         /* fstp st(i) */
 194         FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);
 195         FPU_pop();
 196 }