darlinghq/darling-gdb
1
0
Fork 0
mirror of https://github.com/darlinghq/darling-gdb.git synced 2024-12-12 22:46:16 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity
eba01826a5
darling-gdb/sim/common/sim-alu.h
Michael Meissner 465db791ec Fix problems with d30v addc/subb
1997-11-29 01:14:58 +00:00

547 lines
13 KiB
C
Raw Blame History

/* This file is part of the program psim.
Copyright (C) 1994-1996, Andrew Cagney <cagney@highland.com.au>
Copyright (C) 1997, Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#ifndef _SIM_ALU_H_
#define _SIM_ALU_H_
#include "sim-xcat.h"
/* Binary addition, carry and overflow:
Overflow - method 1:
Overflow occures when the sign of the two operands is identical but
different to the sign of the result:
SIGN_BIT (~(a ^ b) & ((a + b) ^ b))
Note that, for subtraction, care must be taken with MIN_INTn.
Overflow - method 2:
The two N bit operands are sign extended to M>N bits and then
added. Overflow occures when SIGN_BIT<n> and SIGN_BIT<m> do not
match.
SIGN_BIT (r >> (M-N) ^ r)
Overflow - method 3:
The two N bit operands are sign extended to M>N bits and then
added. Overflow occures when the result is outside of signextended
MIN_INTn, MAX_INTn.
Overflow - method 4:
Given the carry bit, the overflow can be computed using the
equation:
SIGN_BIT (((A ^ B) ^ R) ^ C)
As shown in the table below:
I A B R C | V | A^B ^R ^C
---------------+---+-------------
0 0 0 0 0 | 0 | 0 0 0
0 0 1 1 0 | 0 | 1 0 0
0 1 0 1 0 | 0 | 1 0 0
0 1 1 0 1 | 1 | 0 0 1
1 0 0 1 0 | 1 | 0 1 1
1 0 1 0 1 | 0 | 1 1 0
1 1 0 0 1 | 0 | 1 1 0
1 1 1 1 1 | 0 | 0 1 0
Carry - method 1:
Consider the truth table (carryIn, Result, Carryout, Result):
I A B R | C
------------+---
0 0 0 0 | 0
0 0 1 1 | 0
0 1 0 1 | 0
0 1 1 0 | 1
1 0 0 1 | 0
1 0 1 0 | 1
1 1 0 0 | 1
1 1 1 1 | 1
Looking at the terms A, B and R we want an equation for C.
AB\R 0 1
+-------
00 | 0 0
01 | 1 0
11 | 1 1
10 | 1 0
This giving us the sum-of-prod equation:
SIGN_BIT ((A & B) | (A & ~R) | (B & ~R))
Verifying:
I A B R | C | A&B A&~R B&~R
------------+---+---------------
0 0 0 0 | 0 | 0 0 0
0 0 1 1 | 0 | 0 0 0
0 1 0 1 | 0 | 0 0 0
0 1 1 0 | 1 | 1 1 1
1 0 0 1 | 0 | 0 0 0
1 0 1 0 | 1 | 0 0 1
1 1 0 0 | 1 | 0 1 0
1 1 1 1 | 1 | 1 0 0
Carry - method 2:
Given two signed N bit numbers, a carry can be detected by treating
the numbers as N bit unsigned and adding them using M>N unsigned
arrithmetic. Carry is indicated by bit (1 << N) being set (result
>= 2**N).
SIGN_BITm (r)
Carry - method 3:
Given the overflow bit. The carry can be computed from:
(~R&V) | (R&V)
Carry - method 4:
Add the two signed N bit numbers as unsigned N bit numbers, and then
compare the result to either one of the inputs via unsigned compare.
If the result is less than the inputs, carry occurred.
C = ((unsigned)(a+b)) < (unsigned)a if adding
(or)
C = (unsigned)a < (unsigned)b if subtracting
*/
/* 8 bit target expressions:
Since the host's natural bitsize > 8 bits, carry method 2 and
overflow method 2 are used. */
#define ALU8_BEGIN(VAL) \
signed alu8_cr = (unsigned8) (VAL); \
unsigned alu8_vr = (signed8) (alu8_cr)
#define ALU8_SET(VAL) \
alu8_cr = (unsigned8) (VAL); \
alu8_vr = (signed8) (alu8_cr)
#define ALU8_SET_CARRY(CARRY) \
do { \
if (CARRY) \
alu8_cr |= ((signed)-1) << 8; \
else \
alu8_cr &= 0xff; \
} while (0)
#define ALU8_HAD_CARRY (alu8_cr & LSBIT32(8))
#define ALU8_HAD_OVERFLOW (((alu8_vr >> 8) ^ alu8_vr) & LSBIT32 (8-1))
#define ALU8_RESULT ((unsigned8) alu8_cr)
#define ALU8_CARRY_RESULT ((unsigned8) alu8_cr)
#define ALU8_OVERFLOW_RESULT ((unsigned8) alu8_vr)
/* #define ALU8_END ????? - target dependant */
/* 16 bit target expressions:
Since the host's natural bitsize > 16 bits, carry method 2 and
overflow method 2 are used. */
#define ALU16_BEGIN(VAL) \
signed alu16_cr = (unsigned16) (VAL); \
unsigned alu16_vr = (signed16) (alu16_cr)
#define ALU16_SET(VAL) \
alu16_cr = (unsigned16) (VAL); \
alu16_vr = (signed16) (alu16_cr)
#define ALU16_SET_CARRY(CARRY) \
do { \
if (CARRY) \
alu16_cr |= ((signed)-1) << 16; \
else \
alu16_cr &= 0xffff; \
} while (0)
#define ALU16_HAD_CARRY (alu16_cr & LSBIT32(16))
#define ALU16_HAD_OVERFLOW (((alu16_vr >> 16) ^ alu16_vr) & LSBIT32 (16-1))
#define ALU16_RESULT ((unsigned16) alu16_cr)
#define ALU16_CARRY_RESULT ((unsigned16) alu16_cr)
#define ALU16_OVERFLOW_RESULT ((unsigned16) alu16_vr)
/* #define ALU16_END ????? - target dependant */
/* 32 bit target expressions:
Since most hosts do not support 64 (> 32) bit arrithmetic, carry
method 4 and overflow method 4 are used.
FIXME: 64 bit hosts should use the same method as for the 16 bit
ALU. */
#define ALU32_BEGIN(VAL) \
unsigned32 alu32_r = (VAL); \
int alu32_c = 0; \
int alu32_v = 0
#define ALU32_SET(VAL) \
alu32_r = (VAL); \
alu32_c = 0; \
alu32_v = 0
#define ALU32_SET_CARRY(CARRY) alu32_c = (CARRY)
#define ALU32_HAD_OVERFLOW (alu32_v)
#define ALU32_HAD_CARRY (alu32_c)
#define ALU32_RESULT (alu32_r)
#define ALU32_CARRY_RESULT (alu32_r)
#define ALU32_OVERFLOW_RESULT (alu32_r)
/* 64 bit target expressions:
Even though the host typically doesn't support native 64 bit
arrithmetic, it is still used. */
#define ALU64_BEGIN(VAL) \
natural64 alu64_r = (VAL); \
int alu64_c = 0; \
int alu64_v = 0
#define ALU64_SET(VAL) \
alu64_r = (VAL); \
alu64_c = 0; \
alu64_v = 0
#define ALU64_SET_CARRY(CARRY) alu64_c = (CARRY)
#define ALU64_HAD_CARRY (alu64_c)
#define ALU64_HAD_OVERFLOW (alu64_v)
#define ALU64_RESULT (alu64_r)
#define ALU64_CARRY_RESULT (alu64_r)
#define ALU64_OVERFLOW_RESULT (alu64_r)
/* Generic versions of above macros */
#define ALU_BEGIN XCONCAT3(ALU,WITH_TARGET_WORD_BITSIZE,_BEGIN)
#define ALU_SET XCONCAT3(ALU,WITH_TARGET_WORD_BITSIZE,_SET)
#define ALU_SET_CARRY XCONCAT3(ALU,WITH_TARGET_WORD_BITSIZE,_SET_CARRY)
#define ALU_HAD_OVERFLOW XCONCAT3(ALU,WITH_TARGET_WORD_BITSIZE,_HAD_OVERFLOW)
#define ALU_HAD_CARRY XCONCAT3(ALU,WITH_TARGET_WORD_BITSIZE,_HAD_CARRY)
#define ALU_RESULT XCONCAT3(ALU,WITH_TARGET_WORD_BITSIZE,_RESULT)
#define ALU_OVERFLOW_RESULT XCONCAT3(ALU,WITH_TARGET_WORD_BITSIZE,_OVERFLOW_RESULT)
#define ALU_CARRY_RESULT XCONCAT3(ALU,WITH_TARGET_WORD_BITSIZE,_CARRY_RESULT)
/* Basic operations */
#define ALU8_ADD(VAL) \
do { \
unsigned8 alu8_tmp = (VAL); \
alu8_cr += (unsigned8)(alu8_tmp); \
alu8_vr += (signed8)(alu8_tmp); \
} while (0)
#define ALU16_ADD(VAL) \
do { \
unsigned16 alu16_tmp = (VAL); \
alu16_cr += (unsigned16)(alu16_tmp); \
alu16_vr += (signed16)(alu16_tmp); \
} while (0)
#define ALU32_ADD(VAL) \
do { \
unsigned32 alu32_tmp = (unsigned32) (VAL); \
unsigned32 alu32_sign = alu32_tmp ^ alu32_r; \
alu32_r += (alu32_tmp); \
alu32_c = (alu32_r < alu32_tmp); \
alu32_v = ((alu32_sign ^ - (unsigned32)alu32_c) ^ alu32_r) >> 31; \
} while (0)
#define ALU64_ADD(VAL) \
do { \
unsigned64 alu64_tmp = (unsigned64) (VAL); \
unsigned64 alu64_sign = alu64_tmp ^ alu64_r; \
alu64_r += (alu64_tmp); \
alu64_c = (alu64_r < alu64_tmp); \
alu64_v = ((alu64_sign ^ - (unsigned64)alu64_c) ^ alu64_r) >> 63; \
} while (0)
#define ALU_ADD(VAL) XCONCAT3(ALU,WITH_TARGET_WORD_BITSIZE,_ADD)(VAL)
#define ALU8_ADD_CA(VAL) \
do { \
unsigned8 alu8_ca_tmp = (VAL) + ALU8_HAD_CARRY; \
ALU8_ADD(alu8_ca_tmp); \
} while (0)
#define ALU16_ADD_CA(VAL) \
do { \
unsigned16 alu16_ca_tmp = (VAL) + ALU16_HAD_CARRY; \
ALU16_ADD(alu16_ca_tmp); \
} while (0)
#define ALU32_ADD_CA(VAL) \
do { \
unsigned32 alu32_ca_tmp = (VAL) + ALU32_HAD_CARRY; \
ALU32_ADD(alu32_ca_tmp); \
} while (0)
#define ALU64_ADD_CA(VAL) \
do { \
unsigned64 alu64_ca_tmp = (VAL) + ALU64_HAD_CARRY; \
ALU64_ADD(alu64_ca_tmp); \
} while (0)
#define ALU_ADD_CA(VAL) XCONCAT3(ALU,WITH_TARGET_WORD_BITSIZE,_ADD_CA)(VAL)
/* Remember: Hardware implements subtract as an ADD with a carry in of
1 into the least significant bit */
#define ALU8_SUB(VAL) \
do { \
signed alu8sub_val = ~(VAL); \
ALU8_ADD (alu8sub_val); \
ALU8_ADD (1); \
} while (0)
#define ALU16_SUB(VAL) \
do { \
signed alu16sub_val = ~(VAL); \
ALU16_ADD (alu16sub_val); \
ALU16_ADD (1); \
} while (0)
#define ALU32_SUB(VAL) \
do { \
unsigned32 alu32_tmp = (unsigned32) (VAL); \
unsigned32 alu32_sign = alu32_tmp ^ alu32_r; \
alu32_c = (alu32_r < alu32_tmp); \
alu32_r -= (alu32_tmp); \
alu32_v = ((alu32_sign ^ - (unsigned32)alu32_c) ^ alu32_r) >> 31; \
} while (0)
#define ALU64_SUB(VAL) \
do { \
unsigned64 alu64_tmp = (unsigned64) (VAL); \
unsigned64 alu64_sign = alu64_tmp ^ alu64_r; \
alu64_c = (alu64_r < alu64_tmp); \
alu64_r -= (alu64_tmp); \
alu64_v = ((alu64_sign ^ - (unsigned64)alu64_c) ^ alu64_r) >> 63; \
} while (0)
#define ALU_SUB(VAL) XCONCAT3(ALU,WITH_TARGET_WORD_BITSIZE,_SUB)(VAL)
#define ALU8_SUB_CA(VAL) \
do { \
unsigned8 alu8_ca_tmp = (VAL) + ALU8_HAD_CARRY; \
ALU8_SUB(alu8_ca_tmp); \
} while (0)
#define ALU16_SUB_CA(VAL) \
do { \
unsigned16 alu16_ca_tmp = (VAL) + ALU16_HAD_CARRY; \
ALU16_SUB(alu16_ca_tmp); \
} while (0)
#define ALU32_SUB_CA(VAL) \
do { \
unsigned32 alu32_ca_tmp = (VAL) + ALU32_HAD_CARRY; \
ALU32_SUB(alu32_ca_tmp); \
} while (0)
#define ALU64_SUB_CA(VAL) \
do { \
unsigned64 alu64_ca_tmp = (VAL) + ALU64_HAD_CARRY; \
ALU64_SUB(alu64_ca_tmp); \
} while (0)
#define ALU_SUB_CA(VAL) XCONCAT3(ALU,WITH_TARGET_WORD_BITSIZE,_SUB_CA)(VAL)
#define ALU16_OR(VAL) \
do { \
error("ALU16_OR"); \
} while (0)
#define ALU32_OR(VAL) \
do { \
alu32_r |= (VAL); \
alu32_c = 0; \
alu32_v = 0; \
} while (0)
#define ALU64_OR(VAL) \
do { \
alu64_r |= (VAL); \
alu64_c = 0; \
alu64_v = 0; \
} while (0)
#define ALU_OR(VAL) XCONCAT3(ALU,WITH_TARGET_WORD_BITSIZE,_OR)(VAL)
#define ALU16_XOR(VAL) \
do { \
error("ALU16_XOR"); \
} while (0)
#define ALU32_XOR(VAL) \
do { \
alu32_r ^= (VAL); \
alu32_c = 0; \
alu32_v = 0; \
} while (0)
#define ALU64_XOR(VAL) \
do { \
alu64_r ^= (VAL); \
alu64_c = 0; \
alu64_v = 0; \
} while (0)
#define ALU_XOR(VAL) XCONCAT3(ALU,WITH_TARGET_WORD_BITSIZE,_XOR)(VAL)
#define ALU8_NEGATE() \
do { \
signed alu8neg_val = ~(ALU8_RESULT); \
ALU8_SET (1); \
ALU8_ADD (alu8neg_val); \
} while (0)
#define ALU16_NEGATE() \
do { \
signed alu16neg_val = ~(ALU16_RESULT); \
ALU16_SET (1); \
ALU16_ADD (alu16neg_val); \
} while (0)
#define ALU32_NEGATE() \
do { \
unsigned32 alu32_tmp_orig = alu32_r; \
ALU32_SET (0); \
ALU32_SUB (alu32_tmp_orig); \
} while(0)
#define ALU64_NEGATE() \
do { \
unsigned64 alu64_tmp_orig = alu64_r; \
ALU64_SET (0); \
ALU64_SUB (alu64_tmp_orig); \
} while (0)
#define ALU_NEGATE XCONCAT3(ALU,WITH_TARGET_WORD_BITSIZE,_NEGATE)
#define ALU16_AND(VAL) \
do { \
error("ALU_AND16"); \
} while (0)
#define ALU32_AND(VAL) \
do { \
alu32_r &= (VAL); \
alu32_r = 0; \
alu32_v = 0; \
} while (0)
#define ALU64_AND(VAL) \
do { \
alu64_r &= (VAL); \
alu64_r = 0; \
alu64_v = 0; \
} while (0)
#define ALU_AND(VAL) XCONCAT3(ALU,WITH_TARGET_WORD_BITSIZE,_AND)(VAL)
#define ALU16_NOT(VAL) \
do { \
error("ALU_NOT16"); \
} while (0)
#define ALU32_NOT \
do { \
alu32_r = ~alu32_r; \
alu32_c = 0; \
alu32_v = 0; \
} while (0)
#define ALU64_NOT \
do { \
alu64_r = ~alu64_r; \
alu64_c = 0; \
alu64_v = 0; \
} while (0)
#define ALU_NOT XCONCAT3(ALU,WITH_TARGET_WORD_BITSIZE,_NOT)
#endif
Reference in New Issue View Git Blame Copy Permalink