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gbeauche |
1.1 |
/* |
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* fpu/flags.cpp - Floating-point flags |
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* |
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gbeauche |
1.4 |
* Basilisk II (C) 1997-2008 Christian Bauer |
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gbeauche |
1.1 |
* |
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* MC68881/68040 fpu emulation |
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* |
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* Original UAE FPU, copyright 1996 Herman ten Brugge |
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* Rewrite for x86, copyright 1999-2000 Lauri Pesonen |
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* New framework, copyright 2000 Gwenole Beauchesne |
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* Adapted for JIT compilation (c) Bernd Meyer, 2000 |
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* |
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* This program is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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* the Free Software Foundation; either version 2 of the License, or |
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* (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* You should have received a copy of the GNU General Public License |
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* along with this program; if not, write to the Free Software |
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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*/ |
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/* NOTE: this file shall be included only from fpu/fpu_*.cpp */ |
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#undef PRIVATE |
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#define PRIVATE /**/ |
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#undef PUBLIC |
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#define PUBLIC /**/ |
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#undef FFPU |
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#define FFPU /**/ |
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#undef FPU |
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#define FPU fpu. |
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/* -------------------------------------------------------------------------- */ |
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/* --- Native X86 floating-point flags --- */ |
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/* -------------------------------------------------------------------------- */ |
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#ifdef FPU_USE_X86_FLAGS |
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/* Initialization */ |
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void FFPU fpu_init_native_fflags(void) |
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{ |
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// Adapted from fpu_x86.cpp |
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#define SW_Z_I_NAN_MASK (SW_C0|SW_C2|SW_C3) |
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#define SW_Z (SW_C3) |
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#define SW_I (SW_C0|SW_C2) |
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#define SW_NAN (SW_C0) |
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#define SW_FINITE (SW_C2) |
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#define SW_EMPTY_REGISTER (SW_C0|SW_C3) |
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#define SW_DENORMAL (SW_C2|SW_C3) |
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#define SW_UNSUPPORTED (0) |
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#define SW_N (SW_C1) |
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// Sanity checks |
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#if (SW_Z != NATIVE_FFLAG_ZERO) |
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#error "Incorrect X86 Z fflag" |
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#endif |
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#if (SW_I != NATIVE_FFLAG_INFINITY) |
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#error "Incorrect X86 I fflag" |
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#endif |
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#if (SW_N != NATIVE_FFLAG_NEGATIVE) |
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#error "Incorrect X86 N fflag" |
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#endif |
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#if (SW_NAN != NATIVE_FFLAG_NAN) |
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#error "Incorrect X86 NAN fflag" |
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#endif |
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// Native status word to m68k mappings |
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for (uae_u32 i = 0; i < 0x48; i++) { |
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to_m68k_fpcond[i] = 0; |
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const uae_u32 native_fpcond = i << 8; |
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switch (native_fpcond & SW_Z_I_NAN_MASK) { |
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#ifndef FPU_UAE |
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// gb-- enabling it would lead to incorrect drawing of digits |
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// in Speedometer Performance Test |
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case SW_UNSUPPORTED: |
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#endif |
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case SW_NAN: |
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case SW_EMPTY_REGISTER: |
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to_m68k_fpcond[i] |= FPSR_CCB_NAN; |
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break; |
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case SW_FINITE: |
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case SW_DENORMAL: |
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break; |
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case SW_I: |
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to_m68k_fpcond[i] |= FPSR_CCB_INFINITY; |
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break; |
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case SW_Z: |
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to_m68k_fpcond[i] |= FPSR_CCB_ZERO; |
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break; |
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} |
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if (native_fpcond & SW_N) |
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to_m68k_fpcond[i] |= FPSR_CCB_NEGATIVE; |
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} |
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// m68k to native status word mappings |
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for (uae_u32 i = 0; i < 0x10; i++) { |
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const uae_u32 m68k_fpcond = i << 24; |
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if (m68k_fpcond & FPSR_CCB_NAN) |
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to_host_fpcond[i] = SW_NAN; |
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else if (m68k_fpcond & FPSR_CCB_ZERO) |
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to_host_fpcond[i] = SW_Z; |
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else if (m68k_fpcond & FPSR_CCB_INFINITY) |
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to_host_fpcond[i] = SW_I; |
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else |
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to_host_fpcond[i] = SW_FINITE; |
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if (m68k_fpcond & FPSR_CCB_NEGATIVE) |
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to_host_fpcond[i] |= SW_N; |
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} |
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// truth-table for FPU conditions |
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for (uae_u32 host_fpcond = 0; host_fpcond < 0x08; host_fpcond++) { |
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// host_fpcond: C3 on bit 2, C1 and C0 are respectively on bits 1 and 0 |
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const uae_u32 real_host_fpcond = ((host_fpcond & 4) << 12) | ((host_fpcond & 3) << 8); |
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const bool N = ((real_host_fpcond & NATIVE_FFLAG_NEGATIVE) == NATIVE_FFLAG_NEGATIVE); |
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const bool Z = ((real_host_fpcond & NATIVE_FFLAG_ZERO) == NATIVE_FFLAG_ZERO); |
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const bool NaN = ((real_host_fpcond & NATIVE_FFLAG_NAN) == NATIVE_FFLAG_NAN); |
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int value; |
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for (uae_u32 m68k_fpcond = 0; m68k_fpcond < 0x20; m68k_fpcond++) { |
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switch (m68k_fpcond) { |
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case 0x00: value = 0; break; // False |
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case 0x01: value = Z; break; // Equal |
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case 0x02: value = !(NaN || Z || N); break; // Ordered Greater Than |
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case 0x03: value = Z || !(NaN || N); break; // Ordered Greater Than or Equal |
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case 0x04: value = N && !(NaN || Z); break; // Ordered Less Than |
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case 0x05: value = Z || (N && !NaN); break; // Ordered Less Than or Equal |
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case 0x06: value = !(NaN || Z); break; // Ordered Greater or Less Than |
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case 0x07: value = !NaN; break; // Ordered |
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case 0x08: value = NaN; break; // Unordered |
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case 0x09: value = NaN || Z; break; // Unordered or Equal |
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case 0x0a: value = NaN || !(N || Z); break; // Unordered or Greater Than |
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case 0x0b: value = NaN || Z || !N; break; // Unordered or Greater or Equal |
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case 0x0c: value = NaN || (N && !Z); break; // Unordered or Less Than |
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case 0x0d: value = NaN || Z || N; break; // Unordered or Less or Equal |
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case 0x0e: value = !Z; break; // Not Equal |
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case 0x0f: value = 1; break; // True |
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case 0x10: value = 0; break; // Signaling False |
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case 0x11: value = Z; break; // Signaling Equal |
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case 0x12: value = !(NaN || Z || N); break; // Greater Than |
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case 0x13: value = Z || !(NaN || N); break; // Greater Than or Equal |
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case 0x14: value = N && !(NaN || Z); break; // Less Than |
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case 0x15: value = Z || (N && !NaN); break; // Less Than or Equal |
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case 0x16: value = !(NaN || Z); break; // Greater or Less Than |
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case 0x17: value = !NaN; break; // Greater, Less or Equal |
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case 0x18: value = NaN; break; // Not Greater, Less or Equal |
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case 0x19: value = NaN || Z; break; // Not Greater or Less Than |
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case 0x1a: value = NaN || !(N || Z); break; // Not Less Than or Equal |
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case 0x1b: value = NaN || Z || !N; break; // Not Less Than |
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case 0x1c: value = NaN || (N && !Z); break; // Not Greater Than or Equal |
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// case 0x1c: value = !Z && (NaN || N); break; // Not Greater Than or Equal |
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case 0x1d: value = NaN || Z || N; break; // Not Greater Than |
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case 0x1e: value = !Z; break; // Signaling Not Equal |
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case 0x1f: value = 1; break; // Signaling True |
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default: value = -1; |
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} |
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fpcond_truth_table[m68k_fpcond][host_fpcond] = value; |
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} |
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} |
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} |
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#endif |
