| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /*---------------------------------------------------------------------------+ |
| 2 | | fpu_etc.c | |
| 3 | | | |
| 4 | | Implement a few FPU instructions. | |
| 5 | | | |
| 6 | | Copyright (C) 1992,1993,1994,1997 | |
| 7 | | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, | |
| 8 | | Australia. 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 "reg_constant.h" |
| 18 | |
| 19 | |
| 20 | static void fchs(FPU_REG *st0_ptr, u_char st0tag) |
| 21 | { |
| 22 | if ( st0tag ^ TAG_Empty ) |
| 23 | { |
| 24 | signbyte(st0_ptr) ^= SIGN_NEG; |
| 25 | clear_C1(); |
| 26 | } |
| 27 | else |
| 28 | FPU_stack_underflow(); |
| 29 | } |
| 30 | |
| 31 | |
| 32 | static void fabs(FPU_REG *st0_ptr, u_char st0tag) |
| 33 | { |
| 34 | if ( st0tag ^ TAG_Empty ) |
| 35 | { |
| 36 | setpositive(st0_ptr); |
| 37 | clear_C1(); |
| 38 | } |
| 39 | else |
| 40 | FPU_stack_underflow(); |
| 41 | } |
| 42 | |
| 43 | |
| 44 | static void ftst_(FPU_REG *st0_ptr, u_char st0tag) |
| 45 | { |
| 46 | switch (st0tag) |
| 47 | { |
| 48 | case TAG_Zero: |
| 49 | setcc(SW_C3); |
| 50 | break; |
| 51 | case TAG_Valid: |
| 52 | if (getsign(st0_ptr) == SIGN_POS) |
| 53 | setcc(0); |
| 54 | else |
| 55 | setcc(SW_C0); |
| 56 | break; |
| 57 | case TAG_Special: |
| 58 | switch ( FPU_Special(st0_ptr) ) |
| 59 | { |
| 60 | case TW_Denormal: |
| 61 | if (getsign(st0_ptr) == SIGN_POS) |
| 62 | setcc(0); |
| 63 | else |
| 64 | setcc(SW_C0); |
| 65 | if ( denormal_operand() < 0 ) |
| 66 | { |
| 67 | #ifdef PECULIAR_486 |
| 68 | /* This is weird! */ |
| 69 | if (getsign(st0_ptr) == SIGN_POS) |
| 70 | setcc(SW_C3); |
| 71 | #endif /* PECULIAR_486 */ |
| 72 | return; |
| 73 | } |
| 74 | break; |
| 75 | case TW_NaN: |
| 76 | setcc(SW_C0|SW_C2|SW_C3); /* Operand is not comparable */ |
| 77 | EXCEPTION(EX_Invalid); |
| 78 | break; |
| 79 | case TW_Infinity: |
| 80 | if (getsign(st0_ptr) == SIGN_POS) |
| 81 | setcc(0); |
| 82 | else |
| 83 | setcc(SW_C0); |
| 84 | break; |
| 85 | default: |
| 86 | setcc(SW_C0|SW_C2|SW_C3); /* Operand is not comparable */ |
| 87 | EXCEPTION(EX_INTERNAL|0x14); |
| 88 | break; |
| 89 | } |
| 90 | break; |
| 91 | case TAG_Empty: |
| 92 | setcc(SW_C0|SW_C2|SW_C3); |
| 93 | EXCEPTION(EX_StackUnder); |
| 94 | break; |
| 95 | } |
| 96 | } |
| 97 | |
| 98 | |
| 99 | static void fxam(FPU_REG *st0_ptr, u_char st0tag) |
| 100 | { |
| 101 | int c = 0; |
| 102 | switch (st0tag) |
| 103 | { |
| 104 | case TAG_Empty: |
| 105 | c = SW_C3|SW_C0; |
| 106 | break; |
| 107 | case TAG_Zero: |
| 108 | c = SW_C3; |
| 109 | break; |
| 110 | case TAG_Valid: |
| 111 | c = SW_C2; |
| 112 | break; |
| 113 | case TAG_Special: |
| 114 | switch ( FPU_Special(st0_ptr) ) |
| 115 | { |
| 116 | case TW_Denormal: |
| 117 | c = SW_C2|SW_C3; /* Denormal */ |
| 118 | break; |
| 119 | case TW_NaN: |
| 120 | /* We also use NaN for unsupported types. */ |
| 121 | if ( (st0_ptr->sigh & 0x80000000) && (exponent(st0_ptr) == EXP_OVER) ) |
| 122 | c = SW_C0; |
| 123 | break; |
| 124 | case TW_Infinity: |
| 125 | c = SW_C2|SW_C0; |
| 126 | break; |
| 127 | } |
| 128 | } |
| 129 | if ( getsign(st0_ptr) == SIGN_NEG ) |
| 130 | c |= SW_C1; |
| 131 | setcc(c); |
| 132 | } |
| 133 | |
| 134 | |
| 135 | static FUNC_ST0 const fp_etc_table[] = { |
| 136 | fchs, fabs, (FUNC_ST0)FPU_illegal, (FUNC_ST0)FPU_illegal, |
| 137 | ftst_, fxam, (FUNC_ST0)FPU_illegal, (FUNC_ST0)FPU_illegal |
| 138 | }; |
| 139 | |
| 140 | void FPU_etc(void) |
| 141 | { |
| 142 | (fp_etc_table[FPU_rm])(&st(0), FPU_gettag0()); |
| 143 | } |