diff options
Diffstat (limited to 'arch/x86/math-emu/reg_compare.c')
| -rw-r--r-- | arch/x86/math-emu/reg_compare.c | 381 |
1 files changed, 381 insertions, 0 deletions
diff --git a/arch/x86/math-emu/reg_compare.c b/arch/x86/math-emu/reg_compare.c new file mode 100644 index 00000000000..f37c5b5a35a --- /dev/null +++ b/arch/x86/math-emu/reg_compare.c @@ -0,0 +1,381 @@ +/*---------------------------------------------------------------------------+ + | reg_compare.c | + | | + | Compare two floating point registers | + | | + | Copyright (C) 1992,1993,1994,1997 | + | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia | + | E-mail billm@suburbia.net | + | | + | | + +---------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------+ + | compare() is the core FPU_REG comparison function | + +---------------------------------------------------------------------------*/ + +#include "fpu_system.h" +#include "exception.h" +#include "fpu_emu.h" +#include "control_w.h" +#include "status_w.h" + + +static int compare(FPU_REG const *b, int tagb) +{ + int diff, exp0, expb; + u_char st0_tag; + FPU_REG *st0_ptr; + FPU_REG x, y; + u_char st0_sign, signb = getsign(b); + + st0_ptr = &st(0); + st0_tag = FPU_gettag0(); + st0_sign = getsign(st0_ptr); + + if ( tagb == TAG_Special ) + tagb = FPU_Special(b); + if ( st0_tag == TAG_Special ) + st0_tag = FPU_Special(st0_ptr); + + if ( ((st0_tag != TAG_Valid) && (st0_tag != TW_Denormal)) + || ((tagb != TAG_Valid) && (tagb != TW_Denormal)) ) + { + if ( st0_tag == TAG_Zero ) + { + if ( tagb == TAG_Zero ) return COMP_A_eq_B; + if ( tagb == TAG_Valid ) + return ((signb == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B); + if ( tagb == TW_Denormal ) + return ((signb == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B) + | COMP_Denormal; + } + else if ( tagb == TAG_Zero ) + { + if ( st0_tag == TAG_Valid ) + return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B); + if ( st0_tag == TW_Denormal ) + return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B) + | COMP_Denormal; + } + + if ( st0_tag == TW_Infinity ) + { + if ( (tagb == TAG_Valid) || (tagb == TAG_Zero) ) + return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B); + else if ( tagb == TW_Denormal ) + return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B) + | COMP_Denormal; + else if ( tagb == TW_Infinity ) + { + /* The 80486 book says that infinities can be equal! */ + return (st0_sign == signb) ? COMP_A_eq_B : + ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B); + } + /* Fall through to the NaN code */ + } + else if ( tagb == TW_Infinity ) + { + if ( (st0_tag == TAG_Valid) || (st0_tag == TAG_Zero) ) + return ((signb == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B); + if ( st0_tag == TW_Denormal ) + return ((signb == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B) + | COMP_Denormal; + /* Fall through to the NaN code */ + } + + /* The only possibility now should be that one of the arguments + is a NaN */ + if ( (st0_tag == TW_NaN) || (tagb == TW_NaN) ) + { + int signalling = 0, unsupported = 0; + if ( st0_tag == TW_NaN ) + { + signalling = (st0_ptr->sigh & 0xc0000000) == 0x80000000; + unsupported = !((exponent(st0_ptr) == EXP_OVER) + && (st0_ptr->sigh & 0x80000000)); + } + if ( tagb == TW_NaN ) + { + signalling |= (b->sigh & 0xc0000000) == 0x80000000; + unsupported |= !((exponent(b) == EXP_OVER) + && (b->sigh & 0x80000000)); + } + if ( signalling || unsupported ) + return COMP_No_Comp | COMP_SNaN | COMP_NaN; + else + /* Neither is a signaling NaN */ + return COMP_No_Comp | COMP_NaN; + } + + EXCEPTION(EX_Invalid); + } + + if (st0_sign != signb) + { + return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B) + | ( ((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ? + COMP_Denormal : 0); + } + + if ( (st0_tag == TW_Denormal) || (tagb == TW_Denormal) ) + { + FPU_to_exp16(st0_ptr, &x); + FPU_to_exp16(b, &y); + st0_ptr = &x; + b = &y; + exp0 = exponent16(st0_ptr); + expb = exponent16(b); + } + else + { + exp0 = exponent(st0_ptr); + expb = exponent(b); + } + +#ifdef PARANOID + if (!(st0_ptr->sigh & 0x80000000)) EXCEPTION(EX_Invalid); + if (!(b->sigh & 0x80000000)) EXCEPTION(EX_Invalid); +#endif /* PARANOID */ + + diff = exp0 - expb; + if ( diff == 0 ) + { + diff = st0_ptr->sigh - b->sigh; /* Works only if ms bits are + identical */ + if ( diff == 0 ) + { + diff = st0_ptr->sigl > b->sigl; + if ( diff == 0 ) + diff = -(st0_ptr->sigl < b->sigl); + } + } + + if ( diff > 0 ) + { + return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B) + | ( ((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ? + COMP_Denormal : 0); + } + if ( diff < 0 ) + { + return ((st0_sign == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B) + | ( ((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ? + COMP_Denormal : 0); + } + + return COMP_A_eq_B + | ( ((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ? + COMP_Denormal : 0); + +} + + +/* This function requires that st(0) is not empty */ +int FPU_compare_st_data(FPU_REG const *loaded_data, u_char loaded_tag) +{ + int f = 0, c; + + c = compare(loaded_data, loaded_tag); + + if (c & COMP_NaN) + { + EXCEPTION(EX_Invalid); + f = SW_C3 | SW_C2 | SW_C0; + } + else + switch (c & 7) + { + case COMP_A_lt_B: + f = SW_C0; + break; + case COMP_A_eq_B: + f = SW_C3; + break; + case COMP_A_gt_B: + f = 0; + break; + case COMP_No_Comp: + f = SW_C3 | SW_C2 | SW_C0; + break; +#ifdef PARANOID + default: + EXCEPTION(EX_INTERNAL|0x121); + f = SW_C3 | SW_C2 | SW_C0; + break; +#endif /* PARANOID */ + } + setcc(f); + if (c & COMP_Denormal) + { + return denormal_operand() < 0; + } + return 0; +} + + +static int compare_st_st(int nr) +{ + int f = 0, c; + FPU_REG *st_ptr; + + if ( !NOT_EMPTY(0) || !NOT_EMPTY(nr) ) + { + setcc(SW_C3 | SW_C2 | SW_C0); + /* Stack fault */ + EXCEPTION(EX_StackUnder); + return !(control_word & CW_Invalid); + } + + st_ptr = &st(nr); + c = compare(st_ptr, FPU_gettagi(nr)); + if (c & COMP_NaN) + { + setcc(SW_C3 | SW_C2 | SW_C0); + EXCEPTION(EX_Invalid); + return !(control_word & CW_Invalid); + } + else + switch (c & 7) + { + case COMP_A_lt_B: + f = SW_C0; + break; + case COMP_A_eq_B: + f = SW_C3; + break; + case COMP_A_gt_B: + f = 0; + break; + case COMP_No_Comp: + f = SW_C3 | SW_C2 | SW_C0; + break; +#ifdef PARANOID + default: + EXCEPTION(EX_INTERNAL|0x122); + f = SW_C3 | SW_C2 | SW_C0; + break; +#endif /* PARANOID */ + } + setcc(f); + if (c & COMP_Denormal) + { + return denormal_operand() < 0; + } + return 0; +} + + +static int compare_u_st_st(int nr) +{ + int f = 0, c; + FPU_REG *st_ptr; + + if ( !NOT_EMPTY(0) || !NOT_EMPTY(nr) ) + { + setcc(SW_C3 | SW_C2 | SW_C0); + /* Stack fault */ + EXCEPTION(EX_StackUnder); + return !(control_word & CW_Invalid); + } + + st_ptr = &st(nr); + c = compare(st_ptr, FPU_gettagi(nr)); + if (c & COMP_NaN) + { + setcc(SW_C3 | SW_C2 | SW_C0); + if (c & COMP_SNaN) /* This is the only difference between + un-ordered and ordinary comparisons */ + { + EXCEPTION(EX_Invalid); + return !(control_word & CW_Invalid); + } + return 0; + } + else + switch (c & 7) + { + case COMP_A_lt_B: + f = SW_C0; + break; + case COMP_A_eq_B: + f = SW_C3; + break; + case COMP_A_gt_B: + f = 0; + break; + case COMP_No_Comp: + f = SW_C3 | SW_C2 | SW_C0; + break; +#ifdef PARANOID + default: + EXCEPTION(EX_INTERNAL|0x123); + f = SW_C3 | SW_C2 | SW_C0; + break; +#endif /* PARANOID */ + } + setcc(f); + if (c & COMP_Denormal) + { + return denormal_operand() < 0; + } + return 0; +} + +/*---------------------------------------------------------------------------*/ + +void fcom_st(void) +{ + /* fcom st(i) */ + compare_st_st(FPU_rm); +} + + +void fcompst(void) +{ + /* fcomp st(i) */ + if ( !compare_st_st(FPU_rm) ) + FPU_pop(); +} + + +void fcompp(void) +{ + /* fcompp */ + if (FPU_rm != 1) + { + FPU_illegal(); + return; + } + if ( !compare_st_st(1) ) + poppop(); +} + + +void fucom_(void) +{ + /* fucom st(i) */ + compare_u_st_st(FPU_rm); + +} + + +void fucomp(void) +{ + /* fucomp st(i) */ + if ( !compare_u_st_st(FPU_rm) ) + FPU_pop(); +} + + +void fucompp(void) +{ + /* fucompp */ + if (FPU_rm == 1) + { + if ( !compare_u_st_st(1) ) + poppop(); + } + else + FPU_illegal(); +} |