2014-03-30 01:53:07 +00:00
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/* armsupp.c -- ARMulator support code: ARM6 Instruction Emulator.
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Copyright (C) 1994 Advanced RISC Machines Ltd.
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2014-07-23 23:16:40 +00:00
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2014-03-30 01:53:07 +00:00
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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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2014-07-23 23:16:40 +00:00
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2014-03-30 01:53:07 +00:00
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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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2014-07-23 23:16:40 +00:00
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2014-03-30 01:53:07 +00:00
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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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2014-09-12 22:34:51 +00:00
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#include "core/arm/skyeye_common/armdefs.h"
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2014-04-13 01:55:36 +00:00
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2015-02-01 01:34:26 +00:00
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// Unsigned sum of absolute difference
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2014-12-28 11:07:24 +00:00
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u8 ARMul_UnsignedAbsoluteDifference(u8 left, u8 right)
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{
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2015-02-01 01:34:26 +00:00
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if (left > right)
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return left - right;
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2014-12-28 11:07:24 +00:00
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2015-02-01 01:34:26 +00:00
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return right - left;
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2014-03-30 01:53:07 +00:00
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}
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2015-01-12 05:01:46 +00:00
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// Add with carry, indicates if a carry-out or signed overflow occurred.
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u32 AddWithCarry(u32 left, u32 right, u32 carry_in, bool* carry_out_occurred, bool* overflow_occurred)
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{
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u64 unsigned_sum = (u64)left + (u64)right + (u64)carry_in;
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s64 signed_sum = (s64)(s32)left + (s64)(s32)right + (s64)carry_in;
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u64 result = (unsigned_sum & 0xFFFFFFFF);
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if (carry_out_occurred)
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*carry_out_occurred = (result != unsigned_sum);
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if (overflow_occurred)
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*overflow_occurred = ((s64)(s32)result != signed_sum);
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return (u32)result;
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}
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2015-01-05 14:10:59 +00:00
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// Compute whether an addition of A and B, giving RESULT, overflowed.
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bool AddOverflow(ARMword a, ARMword b, ARMword result)
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2014-03-30 01:53:07 +00:00
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{
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2015-01-05 14:10:59 +00:00
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return ((NEG(a) && NEG(b) && POS(result)) ||
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(POS(a) && POS(b) && NEG(result)));
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2014-03-30 01:53:07 +00:00
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}
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2015-01-05 14:10:59 +00:00
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// Compute whether a subtraction of A and B, giving RESULT, overflowed.
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bool SubOverflow(ARMword a, ARMword b, ARMword result)
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2014-03-30 01:53:07 +00:00
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{
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2015-01-05 14:10:59 +00:00
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return ((NEG(a) && POS(b) && POS(result)) ||
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(POS(a) && NEG(b) && NEG(result)));
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2014-03-30 01:53:07 +00:00
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}
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2015-01-02 23:21:45 +00:00
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// Returns true if the Q flag should be set as a result of overflow.
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bool ARMul_AddOverflowQ(ARMword a, ARMword b)
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2014-12-23 14:55:07 +00:00
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{
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u32 result = a + b;
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if (((result ^ a) & (u32)0x80000000) && ((a ^ b) & (u32)0x80000000) == 0)
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2015-01-02 23:21:45 +00:00
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return true;
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return false;
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2014-12-23 14:55:07 +00:00
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}
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2015-02-01 01:34:26 +00:00
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// 8-bit signed saturated addition
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2014-12-29 05:49:10 +00:00
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u8 ARMul_SignedSaturatedAdd8(u8 left, u8 right)
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{
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u8 result = left + right;
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if (((result ^ left) & 0x80) && ((left ^ right) & 0x80) == 0) {
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if (left & 0x80)
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result = 0x80;
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else
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result = 0x7F;
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}
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return result;
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}
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2015-02-01 01:34:26 +00:00
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// 8-bit signed saturated subtraction
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2014-12-29 05:49:10 +00:00
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u8 ARMul_SignedSaturatedSub8(u8 left, u8 right)
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{
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u8 result = left - right;
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if (((result ^ left) & 0x80) && ((left ^ right) & 0x80) != 0) {
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if (left & 0x80)
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result = 0x80;
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else
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result = 0x7F;
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}
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return result;
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}
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2015-02-01 01:34:26 +00:00
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// 16-bit signed saturated addition
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2014-12-29 05:49:10 +00:00
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u16 ARMul_SignedSaturatedAdd16(u16 left, u16 right)
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{
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u16 result = left + right;
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if (((result ^ left) & 0x8000) && ((left ^ right) & 0x8000) == 0) {
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if (left & 0x8000)
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result = 0x8000;
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else
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result = 0x7FFF;
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}
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return result;
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}
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2015-02-01 01:34:26 +00:00
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// 16-bit signed saturated subtraction
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2014-12-29 05:49:10 +00:00
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u16 ARMul_SignedSaturatedSub16(u16 left, u16 right)
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{
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u16 result = left - right;
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if (((result ^ left) & 0x8000) && ((left ^ right) & 0x8000) != 0) {
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if (left & 0x8000)
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result = 0x8000;
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else
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result = 0x7FFF;
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}
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return result;
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}
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2015-02-01 01:34:26 +00:00
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// 8-bit unsigned saturated addition
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2014-12-27 22:06:19 +00:00
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u8 ARMul_UnsignedSaturatedAdd8(u8 left, u8 right)
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{
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u8 result = left + right;
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if (result < left)
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result = 0xFF;
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return result;
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}
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2015-02-01 01:34:26 +00:00
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// 16-bit unsigned saturated addition
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2014-12-27 22:06:19 +00:00
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u16 ARMul_UnsignedSaturatedAdd16(u16 left, u16 right)
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{
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u16 result = left + right;
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if (result < left)
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result = 0xFFFF;
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return result;
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}
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2015-02-01 01:34:26 +00:00
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// 8-bit unsigned saturated subtraction
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2014-12-27 22:06:19 +00:00
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u8 ARMul_UnsignedSaturatedSub8(u8 left, u8 right)
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{
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if (left <= right)
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return 0;
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return left - right;
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}
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2015-02-01 01:34:26 +00:00
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// 16-bit unsigned saturated subtraction
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2014-12-27 22:06:19 +00:00
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u16 ARMul_UnsignedSaturatedSub16(u16 left, u16 right)
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{
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if (left <= right)
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return 0;
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return left - right;
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}
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2014-12-30 03:15:15 +00:00
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// Signed saturation.
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u32 ARMul_SignedSatQ(s32 value, u8 shift, bool* saturation_occurred)
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{
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const u32 max = (1 << shift) - 1;
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const s32 top = (value >> shift);
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if (top > 0) {
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*saturation_occurred = true;
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return max;
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}
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else if (top < -1) {
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*saturation_occurred = true;
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return ~max;
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}
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*saturation_occurred = false;
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return (u32)value;
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}
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// Unsigned saturation
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u32 ARMul_UnsignedSatQ(s32 value, u8 shift, bool* saturation_occurred)
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{
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const u32 max = (1 << shift) - 1;
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if (value < 0) {
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*saturation_occurred = true;
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return 0;
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} else if ((u32)value > max) {
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*saturation_occurred = true;
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return max;
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}
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*saturation_occurred = false;
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return (u32)value;
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}
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2015-03-11 20:10:14 +00:00
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// Whether or not the given CPU is in big endian mode (E bit is set)
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bool InBigEndianMode(ARMul_State* cpu)
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{
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return (cpu->Cpsr & (1 << 9)) != 0;
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}
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2015-03-26 13:21:24 +00:00
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// Whether or not the given CPU is in a mode other than user mode.
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bool InAPrivilegedMode(ARMul_State* cpu)
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{
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return (cpu->Mode != USER32MODE);
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}
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