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Diffstat (limited to 'sys/gnu/fpemul/get_address.c')
| -rw-r--r-- | sys/gnu/fpemul/get_address.c | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/sys/gnu/fpemul/get_address.c b/sys/gnu/fpemul/get_address.c new file mode 100644 index 000000000000..957ea4e2eeba --- /dev/null +++ b/sys/gnu/fpemul/get_address.c @@ -0,0 +1,203 @@ +/* + * get_address.c + * + * Get the effective address from an FPU instruction. + * + * + * Copyright (C) 1992,1993,1994 + * W. Metzenthen, 22 Parker St, Ormond, Vic 3163, + * Australia. E-mail billm@vaxc.cc.monash.edu.au + * All rights reserved. + * + * This copyright notice covers the redistribution and use of the + * FPU emulator developed by W. Metzenthen. It covers only its use + * in the 386BSD, FreeBSD and NetBSD operating systems. Any other + * use is not permitted under this copyright. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must include information specifying + * that source code for the emulator is freely available and include + * either: + * a) an offer to provide the source code for a nominal distribution + * fee, or + * b) list at least two alternative methods whereby the source + * can be obtained, e.g. a publically accessible bulletin board + * and an anonymous ftp site from which the software can be + * downloaded. + * 3. All advertising materials specifically mentioning features or use of + * this emulator must acknowledge that it was developed by W. Metzenthen. + * 4. The name of W. Metzenthen may not be used to endorse or promote + * products derived from this software without specific prior written + * permission. + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, + * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY + * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL + * W. METZENTHEN BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * + * The purpose of this copyright, based upon the Berkeley copyright, is to + * ensure that the covered software remains freely available to everyone. + * + * The software (with necessary differences) is also available, but under + * the terms of the GNU copyleft, for the Linux operating system and for + * the djgpp ms-dos extender. + * + * W. Metzenthen June 1994. + * + * + * $Id: get_address.c,v 1.3 1994/06/10 07:44:29 rich Exp $ + * + */ + +/*---------------------------------------------------------------------------+ + | Note: | + | The file contains code which accesses user memory. | + | Emulator static data may change when user memory is accessed, due to | + | other processes using the emulator while swapping is in progress. | + +---------------------------------------------------------------------------*/ + +#include "param.h" +#include "proc.h" +#include "systm.h" +#include "machine/cpu.h" +#include "machine/pcb.h" +#include "machine/reg.h" + +#include "fpu_emu.h" +#include "fpu_system.h" +#include "exception.h" + +static int reg_offset[] = { +tEAX, tECX, tEDX, tEBX, tESP, tEBP, tESI, tEDI}; +#define REG_(x) (*(((int*)FPU_info) + reg_offset[(x)])) + +void *FPU_data_address; + + +/* Decode the SIB byte. This function assumes mod != 0 */ +static void * +sib(int mod) +{ + unsigned char ss, index, base; + long offset; + + REENTRANT_CHECK(OFF); + base = fubyte((char *) FPU_EIP); /* The SIB byte */ + REENTRANT_CHECK(ON); + FPU_EIP++; + ss = base >> 6; + index = (base >> 3) & 7; + base &= 7; + + if ((mod == 0) && (base == 5)) + offset = 0; /* No base register */ + else + offset = REG_(base); + + if (index == 4) { + /* No index register */ + /* A non-zero ss is illegal */ + if (ss) + EXCEPTION(EX_Invalid); + } else { + offset += (REG_(index)) << ss; + } + + if (mod == 1) { + /* 8 bit signed displacement */ + REENTRANT_CHECK(OFF); + offset += (signed char) fubyte((char *) FPU_EIP); + REENTRANT_CHECK(ON); + FPU_EIP++; + } else + if (mod == 2 || base == 5) { /* The second condition also + * has mod==0 */ + /* 32 bit displacment */ + REENTRANT_CHECK(OFF); + offset += (signed) fuword((unsigned long *) FPU_EIP); + REENTRANT_CHECK(ON); + FPU_EIP += 4; + } + return (void *) offset; +} + + +/* + MOD R/M byte: MOD == 3 has a special use for the FPU + SIB byte used iff R/M = 100b + + 7 6 5 4 3 2 1 0 + ..... ......... ......... + MOD OPCODE(2) R/M + + + SIB byte + + 7 6 5 4 3 2 1 0 + ..... ......... ......... + SS INDEX BASE + +*/ + +void +get_address(unsigned char FPU_modrm) +{ + unsigned char mod; + long *cpu_reg_ptr; + int offset = 0; /* Initialized just to stop compiler warnings. */ + + mod = (FPU_modrm >> 6) & 3; + + if (FPU_rm == 4 && mod != 3) { + FPU_data_address = sib(mod); + return; + } + cpu_reg_ptr = (long *) ®_(FPU_rm); + switch (mod) { + case 0: + if (FPU_rm == 5) { + /* Special case: disp32 */ + REENTRANT_CHECK(OFF); + offset = fuword((unsigned long *) FPU_EIP); + REENTRANT_CHECK(ON); + FPU_EIP += 4; + FPU_data_address = (void *) offset; + return; + } else { + FPU_data_address = (void *) *cpu_reg_ptr; /* Just return the + * contents of the cpu + * register */ + return; + } + case 1: + /* 8 bit signed displacement */ + REENTRANT_CHECK(OFF); + offset = (signed char) fubyte((char *) FPU_EIP); + REENTRANT_CHECK(ON); + FPU_EIP++; + break; + case 2: + /* 32 bit displacement */ + REENTRANT_CHECK(OFF); + offset = (signed) fuword((unsigned long *) FPU_EIP); + REENTRANT_CHECK(ON); + FPU_EIP += 4; + break; + case 3: + /* Not legal for the FPU */ + EXCEPTION(EX_Invalid); + } + + FPU_data_address = offset + (char *) *cpu_reg_ptr; +} |