| /*---------------------------------------------------------------------------+ |
| | 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(); |
| } |