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/*---------------------------------------------------------------------------+

 |  errors.c                                                                 |

 |                                                                           |

 |  The error handling functions for wm-FPU-emu                              |

 |                                                                           |

 | Copyright (C) 1992,1993,1994,1996                                         |

 |                  W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |

 |                  E-mail   billm@jacobi.maths.monash.edu.au                |

 |                                                                           |

 |                                                                           |

 +---------------------------------------------------------------------------*/

/*---------------------------------------------------------------------------+

 | Note:                                                                     |

 |    The file contains code which accesses user memory.                     |

 |    Emulator static data may change when user memory is accessed, due to   |

 |    other processes using the emulator while swapping is in progress.      |

 +---------------------------------------------------------------------------*/

#include <linux/signal.h>

#include <asm/segment.h>

#include "fpu_system.h"

#include "exception.h"

#include "fpu_emu.h"

#include "status_w.h"

#include "control_w.h"

#include "reg_constant.h"

#include "version.h"

/* */

#undef PRINT_MESSAGES

/* */

void Un_impl(void)

{

  unsigned char byte1, FPU_modrm;

  unsigned long address = FPU_ORIG_EIP;

  RE_ENTRANT_CHECK_OFF;

  /* No need to verify_area(), we have previously fetched these bytes. */

  printk("Unimplemented FPU Opcode at eip=%p : ", (void *) address);

  if ( FPU_CS == USER_CS )

    {

      while ( 1 )

        {

          byte1 = get_fs_byte((unsigned char *) address);

          if ( (byte1 & 0xf8) == 0xd8 ) break;

          printk("[%02x]", byte1);

          address++;

        }

      printk("%02x ", byte1);

      FPU_modrm = get_fs_byte(1 + (unsigned char *) address);

      if (FPU_modrm >= 0300)

        printk("%02x (%02x+%d)\n", FPU_modrm, FPU_modrm & 0xf8, FPU_modrm & 7);

      else

        printk("/%d\n", (FPU_modrm >> 3) & 7);

    }

  else

    {

      printk("cs selector = %04x\n", FPU_CS);

    }

  RE_ENTRANT_CHECK_ON;

  EXCEPTION(EX_Invalid);

}

/*

   Called for opcodes which are illegal and which are known to result in a

   SIGILL with a real 80486.

   */

void FPU_illegal(void)

{

  math_abort(FPU_info,SIGILL);

}

void emu_printall(void)

{

  int i;

  static const char *tag_desc[] = { "Valid", "Zero", "ERROR", "ERROR",

                              "DeNorm", "Inf", "NaN", "Empty" };

  unsigned char byte1, FPU_modrm;

  unsigned long address = FPU_ORIG_EIP;

  RE_ENTRANT_CHECK_OFF;

  /* No need to verify_area(), we have previously fetched these bytes. */

  printk("At %p:", (void *) address);

  if ( FPU_CS == USER_CS )

    {

#define MAX_PRINTED_BYTES 20

      for ( i = 0; i < MAX_PRINTED_BYTES; i++ )

        {

          byte1 = get_fs_byte((unsigned char *) address);

          if ( (byte1 & 0xf8) == 0xd8 )

            {

              printk(" %02x", byte1);

              break;

            }

          printk(" [%02x]", byte1);

          address++;

        }

      if ( i == MAX_PRINTED_BYTES )

        printk(" [more..]\n");

      else

        {

          FPU_modrm = get_fs_byte(1 + (unsigned char *) address);

          if (FPU_modrm >= 0300)

            printk(" %02x (%02x+%d)\n", FPU_modrm, FPU_modrm & 0xf8, FPU_modrm & 7);

          else

            printk(" /%d, mod=%d rm=%d\n",

                   (FPU_modrm >> 3) & 7, (FPU_modrm >> 6) & 3, FPU_modrm & 7);

        }

    }

  else

    {

      printk("%04x\n", FPU_CS);

    }

  partial_status = status_word();

#ifdef DEBUGGING

if ( partial_status & SW_Backward )    printk("SW: backward compatibility\n");

if ( partial_status & SW_C3 )          printk("SW: condition bit 3\n");

if ( partial_status & SW_C2 )          printk("SW: condition bit 2\n");

if ( partial_status & SW_C1 )          printk("SW: condition bit 1\n");

if ( partial_status & SW_C0 )          printk("SW: condition bit 0\n");

if ( partial_status & SW_Summary )     printk("SW: exception summary\n");

if ( partial_status & SW_Stack_Fault ) printk("SW: stack fault\n");

if ( partial_status & SW_Precision )   printk("SW: loss of precision\n");

if ( partial_status & SW_Underflow )   printk("SW: underflow\n");

if ( partial_status & SW_Overflow )    printk("SW: overflow\n");

if ( partial_status & SW_Zero_Div )    printk("SW: divide by zero\n");

if ( partial_status & SW_Denorm_Op )   printk("SW: denormalized operand\n");

if ( partial_status & SW_Invalid )     printk("SW: invalid operation\n");

#endif DEBUGGING

  printk(" SW: b=%d st=%ld es=%d sf=%d cc=%d%d%d%d ef=%d%d%d%d%d%d\n",

         partial_status & 0x8000 ? 1 : 0,   /* busy */

         (partial_status & 0x3800) >> 11,   /* stack top pointer */

         partial_status & 0x80 ? 1 : 0,     /* Error summary status */

         partial_status & 0x40 ? 1 : 0,     /* Stack flag */

         partial_status & SW_C3?1:0, partial_status & SW_C2?1:0, /* cc */

         partial_status & SW_C1?1:0, partial_status & SW_C0?1:0, /* cc */

         partial_status & SW_Precision?1:0, partial_status & SW_Underflow?1:0,

         partial_status & SW_Overflow?1:0, partial_status & SW_Zero_Div?1:0,

         partial_status & SW_Denorm_Op?1:0, partial_status & SW_Invalid?1:0);

printk(" CW: ic=%d rc=%ld%ld pc=%ld%ld iem=%d     ef=%d%d%d%d%d%d\n",

         control_word & 0x1000 ? 1 : 0,

         (control_word & 0x800) >> 11, (control_word & 0x400) >> 10,

         (control_word & 0x200) >> 9, (control_word & 0x100) >> 8,

         control_word & 0x80 ? 1 : 0,

         control_word & SW_Precision?1:0, control_word & SW_Underflow?1:0,

         control_word & SW_Overflow?1:0, control_word & SW_Zero_Div?1:0,

         control_word & SW_Denorm_Op?1:0, control_word & SW_Invalid?1:0);

  for ( i = 0; i < 8; i++ )

    {

      FPU_REG *r = &st(i);

      char tagi = r->tag;

      switch (tagi)

        {

        case TW_Empty:

          continue;

          break;

        case TW_Zero:

#if 0

          printk("st(%d)  %c .0000 0000 0000 0000         ",

                 i, r->sign ? '-' : '+');

          break;

#endif

        case TW_Valid:

        case TW_NaN:

/*      case TW_Denormal: */

        case TW_Infinity:

          printk("st(%d)  %c .%04lx %04lx %04lx %04lx e%+-6ld ", i,

                 r->sign ? '-' : '+',

                 (long)(r->sigh >> 16),

                 (long)(r->sigh & 0xFFFF),

                 (long)(r->sigl >> 16),

                 (long)(r->sigl & 0xFFFF),

                 r->exp - EXP_BIAS + 1);

          break;

        default:

          printk("Whoops! Error in errors.c: tag%d is %d ", i, tagi);

          continue;

          break;

        }

      printk("%s\n", tag_desc[(int) (unsigned) tagi]);

    }

  RE_ENTRANT_CHECK_ON;

}

static struct {

  int type;

  const char *name;

} exception_names[] = {

  { EX_StackOver, "stack overflow" },

  { EX_StackUnder, "stack underflow" },

  { EX_Precision, "loss of precision" },

  { EX_Underflow, "underflow" },

  { EX_Overflow, "overflow" },

  { EX_ZeroDiv, "divide by zero" },

  { EX_Denormal, "denormalized operand" },

  { EX_Invalid, "invalid operation" },

  { EX_INTERNAL, "INTERNAL BUG in "FPU_VERSION },

  { 0, NULL }

};

/*

 EX_INTERNAL is always given with a code which indicates where the

 error was detected.

 Internal error types:

       0x14   in fpu_etc.c

       0x1nn  in a *.c file:

              0x101  in reg_add_sub.c

              0x102  in reg_mul.c

              0x104  in poly_atan.c

              0x105  in reg_mul.c

              0x107  in fpu_trig.c

              0x108  in reg_compare.c

              0x109  in reg_compare.c

              0x110  in reg_add_sub.c

              0x111  in fpe_entry.c

              0x112  in fpu_trig.c

              0x113  in errors.c

              0x115  in fpu_trig.c

              0x116  in fpu_trig.c

              0x117  in fpu_trig.c

              0x118  in fpu_trig.c

              0x119  in fpu_trig.c

              0x120  in poly_atan.c

              0x121  in reg_compare.c

              0x122  in reg_compare.c

              0x123  in reg_compare.c

              0x125  in fpu_trig.c

              0x126  in fpu_entry.c

              0x127  in poly_2xm1.c

              0x128  in fpu_entry.c

              0x129  in fpu_entry.c

              0x130  in get_address.c

              0x131  in get_address.c

              0x132  in get_address.c

              0x133  in get_address.c

              0x140  in load_store.c

              0x141  in load_store.c

              0x150  in poly_sin.c

              0x151  in poly_sin.c

              0x160  in reg_ld_str.c

              0x161  in reg_ld_str.c

              0x162  in reg_ld_str.c

              0x163  in reg_ld_str.c

       0x2nn  in an *.S file:

              0x201  in reg_u_add.S

              0x202  in reg_u_div.S

              0x203  in reg_u_div.S

              0x204  in reg_u_div.S

              0x205  in reg_u_mul.S

              0x206  in reg_u_sub.S

              0x207  in wm_sqrt.S

              0x208  in reg_div.S

              0x209  in reg_u_sub.S

              0x210  in reg_u_sub.S

              0x211  in reg_u_sub.S

              0x212  in reg_u_sub.S

              0x213  in wm_sqrt.S

              0x214  in wm_sqrt.S

              0x215  in wm_sqrt.S

              0x220  in reg_norm.S

              0x221  in reg_norm.S

              0x230  in reg_round.S

              0x231  in reg_round.S

              0x232  in reg_round.S

              0x233  in reg_round.S

              0x234  in reg_round.S

              0x235  in reg_round.S

              0x236  in reg_round.S

              0x240  in div_Xsig.S

              0x241  in div_Xsig.S

              0x242  in div_Xsig.S

 */

void exception(int n)

{

  int i, int_type;

  int_type = 0;         /* Needed only to stop compiler warnings */

  if ( n & EX_INTERNAL )

    {

      int_type = n - EX_INTERNAL;

      n = EX_INTERNAL;

      /* Set lots of exception bits! */

      partial_status |= (SW_Exc_Mask | SW_Summary | SW_Backward);

    }

  else

    {

      /* Extract only the bits which we use to set the status word */

      n &= (SW_Exc_Mask);

      /* Set the corresponding exception bit */

      partial_status |= n;

      /* Set summary bits iff exception isn't masked */

      if ( partial_status & ~control_word & CW_Exceptions )

        partial_status |= (SW_Summary | SW_Backward);

      if ( n & (SW_Stack_Fault | EX_Precision) )

        {

          if ( !(n & SW_C1) )

            /* This bit distinguishes over- from underflow for a stack fault,

               and roundup from round-down for precision loss. */

            partial_status &= ~SW_C1;

        }

    }

  RE_ENTRANT_CHECK_OFF;

  if ( (~control_word & n & CW_Exceptions) || (n == EX_INTERNAL) )

    {

#ifdef PRINT_MESSAGES

      /* My message from the sponsor */

      printk(FPU_VERSION" "__DATE__" (C) W. Metzenthen.\n");

#endif PRINT_MESSAGES

      /* Get a name string for error reporting */

      for (i=0; exception_names[i].type; i++)

        if ( (exception_names[i].type & n) == exception_names[i].type )

          break;

      if (exception_names[i].type)

        {

#ifdef PRINT_MESSAGES

          printk("FP Exception: %s!\n", exception_names[i].name);

#endif PRINT_MESSAGES

        }

      else

        printk("FPU emulator: Unknown Exception: 0x%04x!\n", n);

      if ( n == EX_INTERNAL )

        {

          printk("FPU emulator: Internal error type 0x%04x\n", int_type);

          emu_printall();

        }

#ifdef PRINT_MESSAGES

      else

        emu_printall();

#endif PRINT_MESSAGES

      /*

       * The 80486 generates an interrupt on the next non-control FPU

       * instruction. So we need some means of flagging it.

       * We use the ES (Error Summary) bit for this.

       */

    }

  RE_ENTRANT_CHECK_ON;

#ifdef __DEBUG__

  math_abort(FPU_info,SIGFPE);

#endif __DEBUG__

}

/* Real operation attempted on two operands, one a NaN. */

/* Returns nz if the exception is unmasked */

asmlinkage int real_2op_NaN(FPU_REG const *a, FPU_REG const *b, FPU_REG *dest)

{

  FPU_REG const *x;

  int signalling;

  /* The default result for the case of two "equal" NaNs (signs may

     differ) is chosen to reproduce 80486 behaviour */

  x = a;

  if (a->tag == TW_NaN)

    {

      if (b->tag == TW_NaN)

        {

          signalling = !(a->sigh & b->sigh & 0x40000000);

          /* find the "larger" */

          if ( significand(a) < significand(b) )

            x = b;

        }

      else

        {

          /* return the quiet version of the NaN in a */

          signalling = !(a->sigh & 0x40000000);

        }

    }

  else

#ifdef PARANOID

    if (b->tag == TW_NaN)

#endif PARANOID

    {

      signalling = !(b->sigh & 0x40000000);

      x = b;

    }

#ifdef PARANOID

  else

    {

      signalling = 0;

      EXCEPTION(EX_INTERNAL|0x113);

      x = &CONST_QNaN;

    }

#endif PARANOID

  if ( !signalling )

    {

      if ( !(x->sigh & 0x80000000) )  /* pseudo-NaN ? */

        x = &CONST_QNaN;

      reg_move(x, dest);

      return 0;

    }

  if ( control_word & CW_Invalid )

    {

      /* The masked response */

      if ( !(x->sigh & 0x80000000) )  /* pseudo-NaN ? */

        x = &CONST_QNaN;

      reg_move(x, dest);

      /* ensure a Quiet NaN */

      dest->sigh |= 0x40000000;

    }

  EXCEPTION(EX_Invalid);

  return !(control_word & CW_Invalid);

}

/* Invalid arith operation on Valid registers */

/* Returns nz if the exception is unmasked */

asmlinkage int arith_invalid(FPU_REG *dest)

{

  EXCEPTION(EX_Invalid);

  if ( control_word & CW_Invalid )

    {

      /* The masked response */

      reg_move(&CONST_QNaN, dest);

    }

  return !(control_word & CW_Invalid);

}

/* Divide a finite number by zero */

asmlinkage int divide_by_zero(int sign, FPU_REG *dest)

{

  if ( control_word & CW_ZeroDiv )

    {

      /* The masked response */

      reg_move(&CONST_INF, dest);

      dest->sign = (unsigned char)sign;

    }

  EXCEPTION(EX_ZeroDiv);

  return !(control_word & CW_ZeroDiv);

}

/* This may be called often, so keep it lean */

int set_precision_flag(int flags)

{

  if ( control_word & CW_Precision )

    {

      partial_status &= ~(SW_C1 & flags);

      partial_status |= flags;   /* The masked response */

      return 0;

    }

  else

    {

      exception(flags);

      return 1;

    }

}

/* This may be called often, so keep it lean */

asmlinkage void set_precision_flag_up(void)

{

  if ( control_word & CW_Precision )

    partial_status |= (SW_Precision | SW_C1);   /* The masked response */

  else

    exception(EX_Precision | SW_C1);

}

/* This may be called often, so keep it lean */

asmlinkage void set_precision_flag_down(void)

{

  if ( control_word & CW_Precision )

    {   /* The masked response */

      partial_status &= ~SW_C1;

      partial_status |= SW_Precision;

    }

  else

    exception(EX_Precision);

}

asmlinkage int denormal_operand(void)

{

  if ( control_word & CW_Denormal )

    {   /* The masked response */

      partial_status |= SW_Denorm_Op;

      return 0;

    }

  else

    {

      exception(EX_Denormal);

      return 1;

    }

}

asmlinkage int arith_overflow(FPU_REG *dest)

{

  if ( control_word & CW_Overflow )

    {

      char sign;

      /* The masked response */

/* ###### The response here depends upon the rounding mode */

      sign = dest->sign;

      reg_move(&CONST_INF, dest);

      dest->sign = sign;

    }

  else

    {

      /* Subtract the magic number from the exponent */

      dest->exp -= (3 * (1 << 13));

    }

  EXCEPTION(EX_Overflow);

  if ( control_word & CW_Overflow )

    {

      /* The overflow exception is masked. */

      /* By definition, precision is lost.

         The roundup bit (C1) is also set because we have

         "rounded" upwards to Infinity. */

      EXCEPTION(EX_Precision | SW_C1);

      return !(control_word & CW_Precision);

    }

  return 0;

}

asmlinkage int arith_underflow(FPU_REG *dest)

{

  if ( control_word & CW_Underflow )

    {

      /* The masked response */

      if ( dest->exp <= EXP_UNDER - 63 )

        {

          reg_move(&CONST_Z, dest);

          partial_status &= ~SW_C1;       /* Round down. */

        }

    }

  else

    {

      /* Add the magic number to the exponent. */

      dest->exp += (3 * (1 << 13));

    }

  EXCEPTION(EX_Underflow);

  if ( control_word & CW_Underflow )

    {

      /* The underflow exception is masked. */

      EXCEPTION(EX_Precision);

      return !(control_word & CW_Precision);

    }

  return 0;

}

void stack_overflow(void)

{

 if ( control_word & CW_Invalid )

    {

      /* The masked response */

      top--;

      reg_move(&CONST_QNaN, &st(0));

    }

  EXCEPTION(EX_StackOver);

  return;

}

void stack_underflow(void)

{

 if ( control_word & CW_Invalid )

    {

      /* The masked response */

      reg_move(&CONST_QNaN, &st(0));

    }

  EXCEPTION(EX_StackUnder);

  return;

}

void stack_underflow_i(int i)

{

 if ( control_word & CW_Invalid )

    {

      /* The masked response */

      reg_move(&CONST_QNaN, &(st(i)));

    }

  EXCEPTION(EX_StackUnder);

  return;

}

void stack_underflow_pop(int i)

{

 if ( control_word & CW_Invalid )

    {

      /* The masked response */

      reg_move(&CONST_QNaN, &(st(i)));

      pop();

    }

  EXCEPTION(EX_StackUnder);

  return;

}