VEX/useful/show_fp_state.c

   1
   2 #include <stdio.h>
   3 #include <assert.h>
   4
   5
   6 /* ------------------------------------------------- */
   7
   8 typedef unsigned char          UChar;
   9 typedef unsigned short         UShort;
  10 typedef unsigned int           UInt;
  11 typedef unsigned long long int ULong;
  12
  13 typedef signed char     Char;
  14 typedef short           Short;
  15 typedef int             Int;
  16 typedef long long int   Long;
  17
  18 typedef
  19    struct {
  20       UShort env[14];
  21       UChar  reg[80];
  22    }
  23    Fpu_State;
  24
  25 /* Offsets, in 16-bit ints, into the FPU environment (env) area. */
  26 #define FP_ENV_CTRL   0
  27 #define FP_ENV_STAT   2
  28 #define FP_ENV_TAG    4
  29 #define FP_ENV_IP     6 /* and 7 */
  30 #define FP_ENV_CS     8
  31 #define FP_ENV_OPOFF  10 /* and 11 */
  32 #define FP_ENV_OPSEL  12
  33 #define FP_REG(ii)    (10*(7-(ii)))
  34
  35 /* Bitfield offsets for exceptions in the FPU status and control words. */
  36 #define FP_E_INVAL    0
  37 #define FP_E_DENOR    1
  38 #define FP_E_DIVZ     2
  39 #define FP_E_OVERF    3
  40 #define FP_E_UNDER    4
  41 #define FP_E_LOS      5
  42
  43 /* More bitfield offsets, but for the status word only. */
  44 #define FP_E_STACKF   6
  45 #define FP_E_SUMMARY  7
  46 #define FP_F_C0       8
  47 #define FP_F_C1       9
  48 #define FP_F_C2      10
  49 #define FP_F_C3      14
  50 /* top-of-stack ptr is bits 13,12,11 of the word */
  51 #define FP_F_TOS_LO  11
  52 #define FP_F_TOS_HI  13
  53
  54 /* Register tags. */
  55 #define FP_TAG_VALID 0
  56 #define FP_TAG_ZERO  1
  57 #define FP_TAG_SPEC  2
  58 #define FP_TAG_EMPTY 3
  59
  60 char* fp_tag_names[4]
  61    = { "Valid", "Zero", "Spec", "Empty" };
  62
  63 char* fp_exception_names[6]
  64    = { "INVAL", "DENOR", "DIVZ", "OVERF", "UNDERF", "LOS" };
  65
  66 Fpu_State m_fpu_state;
  67
  68
  69
  70 UInt fp_get_tos ( void )
  71 {
  72    return (m_fpu_state.env[FP_ENV_STAT] >> FP_F_TOS_LO) & 7;
  73 }
  74
  75 UInt fp_get_tag ( UInt regno )
  76 {
  77    assert(!(regno < 0 || regno > 7));
  78    return (m_fpu_state.env[FP_ENV_TAG] >> (2*regno)) & 3;
  79 }
  80
  81 UInt fp_get_statusword_flag ( UInt flagno )
  82 {
  83    assert(!(flagno < 0 || flagno > 15));
  84    return (m_fpu_state.env[FP_ENV_STAT] >> flagno) & 0x1;
  85 }
  86
  87 UInt fp_get_controlword_flag ( UInt flagno )
  88 {
  89    assert(!(flagno < 0 || flagno > 15));
  90    return (m_fpu_state.env[FP_ENV_CTRL] >> flagno) & 0x1;
  91 }
  92
  93 static
  94 void printFpuState ( void )
  95 {
  96    Int i, j, k;
  97    assert(sizeof(Fpu_State)==108);
  98    for (i = 7; i >= 0; i--) {
  99       printf ( " %s fpreg%d: 0x",
 100                (UInt)i == fp_get_tos() ? "**" : "  ", i );
 101       for (k = 0, j = FP_REG(i)+9; k < 10; k++,j--)
 102          printf ( "%02x", (UInt)m_fpu_state.reg[j]);
 103       printf ( "  %5s  ", fp_tag_names[fp_get_tag(i)] );
 104       printf("\n");
 105       //printf ( "%20.16e\n", fp_get_reg(i) );
 106    }
 107    printf("     fctrl:     0x%04x  masked: ",
 108           (UInt)m_fpu_state.env[FP_ENV_CTRL] );
 109    for (i = FP_E_INVAL; i <= FP_E_LOS; i++)
 110       if (fp_get_controlword_flag(i))
 111          printf ( "%s ", fp_exception_names[i] );
 112    printf ( "\n" );
 113
 114    printf("     fstat:     0x%04x  except:",
 115           (UInt)m_fpu_state.env[FP_ENV_STAT] );
 116    for (i = FP_E_INVAL; i <= FP_E_LOS; i++)
 117       if (fp_get_statusword_flag(i))
 118          printf ( "%s ", fp_exception_names[i] );
 119    printf ( "  top: %d  ", fp_get_tos() );
 120    printf ( "c3210: %d%d%d%d",
 121             fp_get_statusword_flag(FP_F_C3),
 122             fp_get_statusword_flag(FP_F_C2),
 123             fp_get_statusword_flag(FP_F_C1),
 124             fp_get_statusword_flag(FP_F_C0) );
 125    printf ( "  STACKF: %d\n", fp_get_statusword_flag(FP_E_STACKF) );
 126
 127    printf("      ftag:     0x%04x  ", (UInt)m_fpu_state.env[FP_ENV_TAG] );
 128    for (i = 7; i >= 0; i--)
 129       printf ( "%d:%s ", i, fp_tag_names[fp_get_tag(i)] );
 130    printf("\n");
 131
 132    printf("       fip: 0x%08x\n",
 133            (((UInt)m_fpu_state.env[FP_ENV_IP+1]) << 16) |
 134             ((UInt)m_fpu_state.env[FP_ENV_IP]) );
 135    printf("       fcs:     0x%04x\n",
 136            ((UInt)m_fpu_state.env[FP_ENV_CS]) );
 137    printf("    fopoff: 0x%08x\n",
 138            (((UInt)m_fpu_state.env[FP_ENV_OPOFF+1]) << 16) |
 139             ((UInt)m_fpu_state.env[FP_ENV_OPOFF]) );
 140    printf("    fopsel:     0x%04x\n",
 141            ((UInt)m_fpu_state.env[FP_ENV_OPSEL]) );
 142 }
 143
 144
 145 /* ------------------------------------------------- */
 146
 147
 148 /* Initialise the FPU, dump its state, and print it. */
 149
 150
 151 void show ( unsigned char* st )
 152 {
 153   int i;
 154   for (i = 0; i < 28; i++) {
 155     printf("%02x ", st[i]);
 156     if (i > 0 && ((i & 3) == 3)) printf("\n");
 157   }
 158   for (i = 0; i < 80; i++) {
 159     printf("%02x ", st[i+28]);
 160     if (i > 0 && ((i % 10) == 9)) printf("\n");
 161   }
 162   printf("\n");
 163 }
 164
 165 int main ( void )
 166 {
 167   Fpu_State* st = &m_fpu_state;
 168   assert(sizeof(m_fpu_state) == 108);
 169   asm volatile ("finit ; fnsave %0"
 170                 : "=m" (m_fpu_state)
 171                 :
 172                 : "memory" );
 173   printFpuState();
 174   printf("\n\n");
 175
 176   asm volatile ("fildl 0(%%esp) ; pushl $17 ; fildl 0(%%esp) ; addl $4, %%esp ;  fnsave %0"
 177                 : "=m" (m_fpu_state)
 178                 :
 179                 : "memory" );
 180   printFpuState();
 181   printf("\n");
 182   show(st);
 183   return 0;
 184 }