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(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 static void fstsw_ax(void)
  67 {
  68         *(short *)&FPU_EAX = status_word();
  69         no_ip_update = 1;
  70 }
  71
  72 static FUNC const fstsw_table[] = {
  73         fstsw_ax, FPU_illegal, FPU_illegal, FPU_illegal,
  74         FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal
  75 };
  76
  77 void fstsw_(void)
  78 {
  79         (fstsw_table[FPU_rm]) ();
  80 }
  81
  82 static FUNC const fp_nop_table[] = {
  83         fnop, FPU_illegal, FPU_illegal, FPU_illegal,
  84         FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal
  85 };
  86
  87 void fp_nop(void)
  88 {
  89         (fp_nop_table[FPU_rm]) ();
  90 }
  91
  92 void fld_i_(void)
  93 {
  94         FPU_REG *st_new_ptr;
  95         int i;
  96         u_char tag;
  97
  98         if (STACK_OVERFLOW) {
  99                 FPU_stack_overflow();
 100                 return;
 101         }
 102
 103         /* fld st(i) */
 104         i = FPU_rm;
 105         if (NOT_EMPTY(i)) {
 106                 reg_copy(&st(i), st_new_ptr);
 107                 tag = FPU_gettagi(i);
 108                 push();
 109                 FPU_settag0(tag);
 110         } else {
 111                 if (control_word & CW_Invalid) {
 112                         /* The masked response */
 113                         FPU_stack_underflow();
 114                 } else
 115                         EXCEPTION(EX_StackUnder);
 116         }
 117
 118 }
 119
 120 void fxch_i(void)
 121 {
 122         /* fxch st(i) */
 123         FPU_REG t;
 124         int i = FPU_rm;
 125         FPU_REG *st0_ptr = &st(0), *sti_ptr = &st(i);
 126         long tag_word = fpu_tag_word;
 127         int regnr = top & 7, regnri = ((regnr + i) & 7);
 128         u_char st0_tag = (tag_word >> (regnr * 2)) & 3;
 129         u_char sti_tag = (tag_word >> (regnri * 2)) & 3;
 130
 131         if (st0_tag == TAG_Empty) {
 132                 if (sti_tag == TAG_Empty) {
 133                         FPU_stack_underflow();
 134                         FPU_stack_underflow_i(i);
 135                         return;
 136                 }
 137                 if (control_word & CW_Invalid) {
 138                         /* Masked response */
 139                         FPU_copy_to_reg0(sti_ptr, sti_tag);
 140                 }
 141                 FPU_stack_underflow_i(i);
 142                 return;
 143         }
 144         if (sti_tag == TAG_Empty) {
 145                 if (control_word & CW_Invalid) {
 146                         /* Masked response */
 147                         FPU_copy_to_regi(st0_ptr, st0_tag, i);
 148                 }
 149                 FPU_stack_underflow();
 150                 return;
 151         }
 152         clear_C1();
 153
 154         reg_copy(st0_ptr, &t);
 155         reg_copy(sti_ptr, st0_ptr);
 156         reg_copy(&t, sti_ptr);
 157
 158         tag_word &= ~(3 << (regnr * 2)) & ~(3 << (regnri * 2));
 159         tag_word |= (sti_tag << (regnr * 2)) | (st0_tag << (regnri * 2));
 160         fpu_tag_word = tag_word;
 161 }
 162
 163 void ffree_(void)
 164 {
 165         /* ffree st(i) */
 166         FPU_settagi(FPU_rm, TAG_Empty);
 167 }
 168
 169 void ffreep(void)
 170 {
 171         /* ffree st(i) + pop - unofficial code */
 172         FPU_settagi(FPU_rm, TAG_Empty);
 173         FPU_pop();
 174 }
 175
 176 void fst_i_(void)
 177 {
 178         /* fst st(i) */
 179         FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);
 180 }
 181
 182 void fstp_i(void)
 183 {
 184         /* fstp st(i) */
 185         FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);
 186         FPU_pop();
 187 }