diff options
Diffstat (limited to 'drivers/bios_emulator/x86emu/decode.c')
| -rw-r--r-- | drivers/bios_emulator/x86emu/decode.c | 1144 |
1 files changed, 1144 insertions, 0 deletions
diff --git a/drivers/bios_emulator/x86emu/decode.c b/drivers/bios_emulator/x86emu/decode.c new file mode 100644 index 0000000..1e2dcfe --- /dev/null +++ b/drivers/bios_emulator/x86emu/decode.c @@ -0,0 +1,1144 @@ +/**************************************************************************** +* +* Realmode X86 Emulator Library +* +* Copyright (C) 1991-2004 SciTech Software, Inc. +* Copyright (C) David Mosberger-Tang +* Copyright (C) 1999 Egbert Eich +* +* ======================================================================== +* +* Permission to use, copy, modify, distribute, and sell this software and +* its documentation for any purpose is hereby granted without fee, +* provided that the above copyright notice appear in all copies and that +* both that copyright notice and this permission notice appear in +* supporting documentation, and that the name of the authors not be used +* in advertising or publicity pertaining to distribution of the software +* without specific, written prior permission. The authors makes no +* representations about the suitability of this software for any purpose. +* It is provided "as is" without express or implied warranty. +* +* THE AUTHORS DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, +* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO +* EVENT SHALL THE AUTHORS BE LIABLE FOR ANY SPECIAL, INDIRECT OR +* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF +* USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR +* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR +* PERFORMANCE OF THIS SOFTWARE. +* +* ======================================================================== +* +* Language: ANSI C +* Environment: Any +* Developer: Kendall Bennett +* +* Description: This file includes subroutines which are related to +* instruction decoding and accessess of immediate data via IP. etc. +* +****************************************************************************/ + +#include "x86emu/x86emui.h" + +/*----------------------------- Implementation ----------------------------*/ + +/**************************************************************************** +REMARKS: +Handles any pending asychronous interrupts. +****************************************************************************/ +static void x86emu_intr_handle(void) +{ + u8 intno; + + if (M.x86.intr & INTR_SYNCH) { + intno = M.x86.intno; + if (_X86EMU_intrTab[intno]) { + (*_X86EMU_intrTab[intno])(intno); + } else { + push_word((u16)M.x86.R_FLG); + CLEAR_FLAG(F_IF); + CLEAR_FLAG(F_TF); + push_word(M.x86.R_CS); + M.x86.R_CS = mem_access_word(intno * 4 + 2); + push_word(M.x86.R_IP); + M.x86.R_IP = mem_access_word(intno * 4); + M.x86.intr = 0; + } + } +} + +/**************************************************************************** +PARAMETERS: +intrnum - Interrupt number to raise + +REMARKS: +Raise the specified interrupt to be handled before the execution of the +next instruction. +****************************************************************************/ +void x86emu_intr_raise( + u8 intrnum) +{ + M.x86.intno = intrnum; + M.x86.intr |= INTR_SYNCH; +} + +/**************************************************************************** +REMARKS: +Main execution loop for the emulator. We return from here when the system +halts, which is normally caused by a stack fault when we return from the +original real mode call. +****************************************************************************/ +void X86EMU_exec(void) +{ + u8 op1; + + M.x86.intr = 0; + DB(x86emu_end_instr();) + + for (;;) { +DB( if (CHECK_IP_FETCH()) + x86emu_check_ip_access();) + /* If debugging, save the IP and CS values. */ + SAVE_IP_CS(M.x86.R_CS, M.x86.R_IP); + INC_DECODED_INST_LEN(1); + if (M.x86.intr) { + if (M.x86.intr & INTR_HALTED) { +DB( if (M.x86.R_SP != 0) { + printk("halted\n"); + X86EMU_trace_regs(); + } + else { + if (M.x86.debug) + printk("Service completed successfully\n"); + }) + return; + } + if (((M.x86.intr & INTR_SYNCH) && (M.x86.intno == 0 || M.x86.intno == 2)) || + !ACCESS_FLAG(F_IF)) { + x86emu_intr_handle(); + } + } + op1 = (*sys_rdb)(((u32)M.x86.R_CS << 4) + (M.x86.R_IP++)); + (*x86emu_optab[op1])(op1); + if (M.x86.debug & DEBUG_EXIT) { + M.x86.debug &= ~DEBUG_EXIT; + return; + } + } +} + +/**************************************************************************** +REMARKS: +Halts the system by setting the halted system flag. +****************************************************************************/ +void X86EMU_halt_sys(void) +{ + M.x86.intr |= INTR_HALTED; +} + +/**************************************************************************** +PARAMETERS: +mod - Mod value from decoded byte +regh - Reg h value from decoded byte +regl - Reg l value from decoded byte + +REMARKS: +Raise the specified interrupt to be handled before the execution of the +next instruction. + +NOTE: Do not inline this function, as (*sys_rdb) is already inline! +****************************************************************************/ +void fetch_decode_modrm( + int *mod, + int *regh, + int *regl) +{ + int fetched; + +DB( if (CHECK_IP_FETCH()) + x86emu_check_ip_access();) + fetched = (*sys_rdb)(((u32)M.x86.R_CS << 4) + (M.x86.R_IP++)); + INC_DECODED_INST_LEN(1); + *mod = (fetched >> 6) & 0x03; + *regh = (fetched >> 3) & 0x07; + *regl = (fetched >> 0) & 0x07; +} + +/**************************************************************************** +RETURNS: +Immediate byte value read from instruction queue + +REMARKS: +This function returns the immediate byte from the instruction queue, and +moves the instruction pointer to the next value. + +NOTE: Do not inline this function, as (*sys_rdb) is already inline! +****************************************************************************/ +u8 fetch_byte_imm(void) +{ + u8 fetched; + +DB( if (CHECK_IP_FETCH()) + x86emu_check_ip_access();) + fetched = (*sys_rdb)(((u32)M.x86.R_CS << 4) + (M.x86.R_IP++)); + INC_DECODED_INST_LEN(1); + return fetched; +} + +/**************************************************************************** +RETURNS: +Immediate word value read from instruction queue + +REMARKS: +This function returns the immediate byte from the instruction queue, and +moves the instruction pointer to the next value. + +NOTE: Do not inline this function, as (*sys_rdw) is already inline! +****************************************************************************/ +u16 fetch_word_imm(void) +{ + u16 fetched; + +DB( if (CHECK_IP_FETCH()) + x86emu_check_ip_access();) + fetched = (*sys_rdw)(((u32)M.x86.R_CS << 4) + (M.x86.R_IP)); + M.x86.R_IP += 2; + INC_DECODED_INST_LEN(2); + return fetched; +} + +/**************************************************************************** +RETURNS: +Immediate lone value read from instruction queue + +REMARKS: +This function returns the immediate byte from the instruction queue, and +moves the instruction pointer to the next value. + +NOTE: Do not inline this function, as (*sys_rdw) is already inline! +****************************************************************************/ +u32 fetch_long_imm(void) +{ + u32 fetched; + +DB( if (CHECK_IP_FETCH()) + x86emu_check_ip_access();) + fetched = (*sys_rdl)(((u32)M.x86.R_CS << 4) + (M.x86.R_IP)); + M.x86.R_IP += 4; + INC_DECODED_INST_LEN(4); + return fetched; +} + +/**************************************************************************** +RETURNS: +Value of the default data segment + +REMARKS: +Inline function that returns the default data segment for the current +instruction. + +On the x86 processor, the default segment is not always DS if there is +no segment override. Address modes such as -3[BP] or 10[BP+SI] all refer to +addresses relative to SS (ie: on the stack). So, at the minimum, all +decodings of addressing modes would have to set/clear a bit describing +whether the access is relative to DS or SS. That is the function of the +cpu-state-varible M.x86.mode. There are several potential states: + + repe prefix seen (handled elsewhere) + repne prefix seen (ditto) + + cs segment override + ds segment override + es segment override + fs segment override + gs segment override + ss segment override + + ds/ss select (in absense of override) + +Each of the above 7 items are handled with a bit in the mode field. +****************************************************************************/ +_INLINE u32 get_data_segment(void) +{ +#define GET_SEGMENT(segment) + switch (M.x86.mode & SYSMODE_SEGMASK) { + case 0: /* default case: use ds register */ + case SYSMODE_SEGOVR_DS: + case SYSMODE_SEGOVR_DS | SYSMODE_SEG_DS_SS: + return M.x86.R_DS; + case SYSMODE_SEG_DS_SS: /* non-overridden, use ss register */ + return M.x86.R_SS; + case SYSMODE_SEGOVR_CS: + case SYSMODE_SEGOVR_CS | SYSMODE_SEG_DS_SS: + return M.x86.R_CS; + case SYSMODE_SEGOVR_ES: + case SYSMODE_SEGOVR_ES | SYSMODE_SEG_DS_SS: + return M.x86.R_ES; + case SYSMODE_SEGOVR_FS: + case SYSMODE_SEGOVR_FS | SYSMODE_SEG_DS_SS: + return M.x86.R_FS; + case SYSMODE_SEGOVR_GS: + case SYSMODE_SEGOVR_GS | SYSMODE_SEG_DS_SS: + return M.x86.R_GS; + case SYSMODE_SEGOVR_SS: + case SYSMODE_SEGOVR_SS | SYSMODE_SEG_DS_SS: + return M.x86.R_SS; + default: +#ifdef DEBUG + printk("error: should not happen: multiple overrides.\n"); +#endif + HALT_SYS(); + return 0; + } +} + +/**************************************************************************** +PARAMETERS: +offset - Offset to load data from + +RETURNS: +Byte value read from the absolute memory location. + +NOTE: Do not inline this function as (*sys_rdX) is already inline! +****************************************************************************/ +u8 fetch_data_byte( + uint offset) +{ +#ifdef DEBUG + if (CHECK_DATA_ACCESS()) + x86emu_check_data_access((u16)get_data_segment(), offset); +#endif + return (*sys_rdb)((get_data_segment() << 4) + offset); +} + +/**************************************************************************** +PARAMETERS: +offset - Offset to load data from + +RETURNS: +Word value read from the absolute memory location. + +NOTE: Do not inline this function as (*sys_rdX) is already inline! +****************************************************************************/ +u16 fetch_data_word( + uint offset) +{ +#ifdef DEBUG + if (CHECK_DATA_ACCESS()) + x86emu_check_data_access((u16)get_data_segment(), offset); +#endif + return (*sys_rdw)((get_data_segment() << 4) + offset); +} + +/**************************************************************************** +PARAMETERS: +offset - Offset to load data from + +RETURNS: +Long value read from the absolute memory location. + +NOTE: Do not inline this function as (*sys_rdX) is already inline! +****************************************************************************/ +u32 fetch_data_long( + uint offset) +{ +#ifdef DEBUG + if (CHECK_DATA_ACCESS()) + x86emu_check_data_access((u16)get_data_segment(), offset); +#endif + return (*sys_rdl)((get_data_segment() << 4) + offset); +} + +/**************************************************************************** +PARAMETERS: +segment - Segment to load data from +offset - Offset to load data from + +RETURNS: +Byte value read from the absolute memory location. + +NOTE: Do not inline this function as (*sys_rdX) is already inline! +****************************************************************************/ +u8 fetch_data_byte_abs( + uint segment, + uint offset) +{ +#ifdef DEBUG + if (CHECK_DATA_ACCESS()) + x86emu_check_data_access(segment, offset); +#endif + return (*sys_rdb)(((u32)segment << 4) + offset); +} + +/**************************************************************************** +PARAMETERS: +segment - Segment to load data from +offset - Offset to load data from + +RETURNS: +Word value read from the absolute memory location. + +NOTE: Do not inline this function as (*sys_rdX) is already inline! +****************************************************************************/ +u16 fetch_data_word_abs( + uint segment, + uint offset) +{ +#ifdef DEBUG + if (CHECK_DATA_ACCESS()) + x86emu_check_data_access(segment, offset); +#endif + return (*sys_rdw)(((u32)segment << 4) + offset); +} + +/**************************************************************************** +PARAMETERS: +segment - Segment to load data from +offset - Offset to load data from + +RETURNS: +Long value read from the absolute memory location. + +NOTE: Do not inline this function as (*sys_rdX) is already inline! +****************************************************************************/ +u32 fetch_data_long_abs( + uint segment, + uint offset) +{ +#ifdef DEBUG + if (CHECK_DATA_ACCESS()) + x86emu_check_data_access(segment, offset); +#endif + return (*sys_rdl)(((u32)segment << 4) + offset); +} + +/**************************************************************************** +PARAMETERS: +offset - Offset to store data at +val - Value to store + +REMARKS: +Writes a word value to an segmented memory location. The segment used is +the current 'default' segment, which may have been overridden. + +NOTE: Do not inline this function as (*sys_wrX) is already inline! +****************************************************************************/ +void store_data_byte( + uint offset, + u8 val) +{ +#ifdef DEBUG + if (CHECK_DATA_ACCESS()) + x86emu_check_data_access((u16)get_data_segment(), offset); +#endif + (*sys_wrb)((get_data_segment() << 4) + offset, val); +} + +/**************************************************************************** +PARAMETERS: +offset - Offset to store data at +val - Value to store + +REMARKS: +Writes a word value to an segmented memory location. The segment used is +the current 'default' segment, which may have been overridden. + +NOTE: Do not inline this function as (*sys_wrX) is already inline! +****************************************************************************/ +void store_data_word( + uint offset, + u16 val) +{ +#ifdef DEBUG + if (CHECK_DATA_ACCESS()) + x86emu_check_data_access((u16)get_data_segment(), offset); +#endif + (*sys_wrw)((get_data_segment() << 4) + offset, val); +} + +/**************************************************************************** +PARAMETERS: +offset - Offset to store data at +val - Value to store + +REMARKS: +Writes a long value to an segmented memory location. The segment used is +the current 'default' segment, which may have been overridden. + +NOTE: Do not inline this function as (*sys_wrX) is already inline! +****************************************************************************/ +void store_data_long( + uint offset, + u32 val) +{ +#ifdef DEBUG + if (CHECK_DATA_ACCESS()) + x86emu_check_data_access((u16)get_data_segment(), offset); +#endif + (*sys_wrl)((get_data_segment() << 4) + offset, val); +} + +/**************************************************************************** +PARAMETERS: +segment - Segment to store data at +offset - Offset to store data at +val - Value to store + +REMARKS: +Writes a byte value to an absolute memory location. + +NOTE: Do not inline this function as (*sys_wrX) is already inline! +****************************************************************************/ +void store_data_byte_abs( + uint segment, + uint offset, + u8 val) +{ +#ifdef DEBUG + if (CHECK_DATA_ACCESS()) + x86emu_check_data_access(segment, offset); +#endif + (*sys_wrb)(((u32)segment << 4) + offset, val); +} + +/**************************************************************************** +PARAMETERS: +segment - Segment to store data at +offset - Offset to store data at +val - Value to store + +REMARKS: +Writes a word value to an absolute memory location. + +NOTE: Do not inline this function as (*sys_wrX) is already inline! +****************************************************************************/ +void store_data_word_abs( + uint segment, + uint offset, + u16 val) +{ +#ifdef DEBUG + if (CHECK_DATA_ACCESS()) + x86emu_check_data_access(segment, offset); +#endif + (*sys_wrw)(((u32)segment << 4) + offset, val); +} + +/**************************************************************************** +PARAMETERS: +segment - Segment to store data at +offset - Offset to store data at +val - Value to store + +REMARKS: +Writes a long value to an absolute memory location. + +NOTE: Do not inline this function as (*sys_wrX) is already inline! +****************************************************************************/ +void store_data_long_abs( + uint segment, + uint offset, + u32 val) +{ +#ifdef DEBUG + if (CHECK_DATA_ACCESS()) + x86emu_check_data_access(segment, offset); +#endif + (*sys_wrl)(((u32)segment << 4) + offset, val); +} + +/**************************************************************************** +PARAMETERS: +reg - Register to decode + +RETURNS: +Pointer to the appropriate register + +REMARKS: +Return a pointer to the register given by the R/RM field of the +modrm byte, for byte operands. Also enables the decoding of instructions. +****************************************************************************/ +u8* decode_rm_byte_register( + int reg) +{ + switch (reg) { + case 0: + DECODE_PRINTF("AL"); + return &M.x86.R_AL; + case 1: + DECODE_PRINTF("CL"); + return &M.x86.R_CL; + case 2: + DECODE_PRINTF("DL"); + return &M.x86.R_DL; + case 3: + DECODE_PRINTF("BL"); + return &M.x86.R_BL; + case 4: + DECODE_PRINTF("AH"); + return &M.x86.R_AH; + case 5: + DECODE_PRINTF("CH"); + return &M.x86.R_CH; + case 6: + DECODE_PRINTF("DH"); + return &M.x86.R_DH; + case 7: + DECODE_PRINTF("BH"); + return &M.x86.R_BH; + } + HALT_SYS(); + return NULL; /* NOT REACHED OR REACHED ON ERROR */ +} + +/**************************************************************************** +PARAMETERS: +reg - Register to decode + +RETURNS: +Pointer to the appropriate register + +REMARKS: +Return a pointer to the register given by the R/RM field of the +modrm byte, for word operands. Also enables the decoding of instructions. +****************************************************************************/ +u16* decode_rm_word_register( + int reg) +{ + switch (reg) { + case 0: + DECODE_PRINTF("AX"); + return &M.x86.R_AX; + case 1: + DECODE_PRINTF("CX"); + return &M.x86.R_CX; + case 2: + DECODE_PRINTF("DX"); + return &M.x86.R_DX; + case 3: + DECODE_PRINTF("BX"); + return &M.x86.R_BX; + case 4: + DECODE_PRINTF("SP"); + return &M.x86.R_SP; + case 5: + DECODE_PRINTF("BP"); + return &M.x86.R_BP; + case 6: + DECODE_PRINTF("SI"); + return &M.x86.R_SI; + case 7: + DECODE_PRINTF("DI"); + return &M.x86.R_DI; + } + HALT_SYS(); + return NULL; /* NOTREACHED OR REACHED ON ERROR */ +} + +/**************************************************************************** +PARAMETERS: +reg - Register to decode + +RETURNS: +Pointer to the appropriate register + +REMARKS: +Return a pointer to the register given by the R/RM field of the +modrm byte, for dword operands. Also enables the decoding of instructions. +****************************************************************************/ +u32* decode_rm_long_register( + int reg) +{ + switch (reg) { + case 0: + DECODE_PRINTF("EAX"); + return &M.x86.R_EAX; + case 1: + DECODE_PRINTF("ECX"); + return &M.x86.R_ECX; + case 2: + DECODE_PRINTF("EDX"); + return &M.x86.R_EDX; + case 3: + DECODE_PRINTF("EBX"); + return &M.x86.R_EBX; + case 4: + DECODE_PRINTF("ESP"); + return &M.x86.R_ESP; + case 5: + DECODE_PRINTF("EBP"); + return &M.x86.R_EBP; + case 6: + DECODE_PRINTF("ESI"); + return &M.x86.R_ESI; + case 7: + DECODE_PRINTF("EDI"); + return &M.x86.R_EDI; + } + HALT_SYS(); + return NULL; /* NOTREACHED OR REACHED ON ERROR */ +} + +/**************************************************************************** +PARAMETERS: +reg - Register to decode + +RETURNS: +Pointer to the appropriate register + +REMARKS: +Return a pointer to the register given by the R/RM field of the +modrm byte, for word operands, modified from above for the weirdo +special case of segreg operands. Also enables the decoding of instructions. +****************************************************************************/ +u16* decode_rm_seg_register( + int reg) +{ + switch (reg) { + case 0: + DECODE_PRINTF("ES"); + return &M.x86.R_ES; + case 1: + DECODE_PRINTF("CS"); + return &M.x86.R_CS; + case 2: + DECODE_PRINTF("SS"); + return &M.x86.R_SS; + case 3: + DECODE_PRINTF("DS"); + return &M.x86.R_DS; + case 4: + DECODE_PRINTF("FS"); + return &M.x86.R_FS; + case 5: + DECODE_PRINTF("GS"); + return &M.x86.R_GS; + case 6: + case 7: + DECODE_PRINTF("ILLEGAL SEGREG"); + break; + } + HALT_SYS(); + return NULL; /* NOT REACHED OR REACHED ON ERROR */ +} + +/**************************************************************************** +PARAMETERS: +scale - scale value of SIB byte +index - index value of SIB byte + +RETURNS: +Value of scale * index + +REMARKS: +Decodes scale/index of SIB byte and returns relevant offset part of +effective address. +****************************************************************************/ +unsigned decode_sib_si( + int scale, + int index) +{ + scale = 1 << scale; + if (scale > 1) { + DECODE_PRINTF2("[%d*", scale); + } else { + DECODE_PRINTF("["); + } + switch (index) { + case 0: + DECODE_PRINTF("EAX]"); + return M.x86.R_EAX * index; + case 1: + DECODE_PRINTF("ECX]"); + return M.x86.R_ECX * index; + case 2: + DECODE_PRINTF("EDX]"); + return M.x86.R_EDX * index; + case 3: + DECODE_PRINTF("EBX]"); + return M.x86.R_EBX * index; + case 4: + DECODE_PRINTF("0]"); + return 0; + case 5: + DECODE_PRINTF("EBP]"); + return M.x86.R_EBP * index; + case 6: + DECODE_PRINTF("ESI]"); + return M.x86.R_ESI * index; + case 7: + DECODE_PRINTF("EDI]"); + return M.x86.R_EDI * index; + } + HALT_SYS(); + return 0; /* NOT REACHED OR REACHED ON ERROR */ +} + +/**************************************************************************** +PARAMETERS: +mod - MOD value of preceding ModR/M byte + +RETURNS: +Offset in memory for the address decoding + +REMARKS: +Decodes SIB addressing byte and returns calculated effective address. +****************************************************************************/ +unsigned decode_sib_address( + int mod) +{ + int sib = fetch_byte_imm(); + int ss = (sib >> 6) & 0x03; + int index = (sib >> 3) & 0x07; + int base = sib & 0x07; + int offset = 0; + int displacement; + + switch (base) { + case 0: + DECODE_PRINTF("[EAX]"); + offset = M.x86.R_EAX; + break; + case 1: + DECODE_PRINTF("[ECX]"); + offset = M.x86.R_ECX; + break; + case 2: + DECODE_PRINTF("[EDX]"); + offset = M.x86.R_EDX; + break; + case 3: + DECODE_PRINTF("[EBX]"); + offset = M.x86.R_EBX; + break; + case 4: + DECODE_PRINTF("[ESP]"); + offset = M.x86.R_ESP; + break; + case 5: + switch (mod) { + case 0: + displacement = (s32)fetch_long_imm(); + DECODE_PRINTF2("[%d]", displacement); + offset = displacement; + break; + case 1: + displacement = (s8)fetch_byte_imm(); + DECODE_PRINTF2("[%d][EBP]", displacement); + offset = M.x86.R_EBP + displacement; + break; + case 2: + displacement = (s32)fetch_long_imm(); + DECODE_PRINTF2("[%d][EBP]", displacement); + offset = M.x86.R_EBP + displacement; + break; + default: + HALT_SYS(); + } + DECODE_PRINTF("[EAX]"); + offset = M.x86.R_EAX; + break; + case 6: + DECODE_PRINTF("[ESI]"); + offset = M.x86.R_ESI; + break; + case 7: + DECODE_PRINTF("[EDI]"); + offset = M.x86.R_EDI; + break; + default: + HALT_SYS(); + } + offset += decode_sib_si(ss, index); + return offset; + +} + +/**************************************************************************** +PARAMETERS: +rm - RM value to decode + +RETURNS: +Offset in memory for the address decoding + +REMARKS: +Return the offset given by mod=00 addressing. Also enables the +decoding of instructions. + +NOTE: The code which specifies the corresponding segment (ds vs ss) + below in the case of [BP+..]. The assumption here is that at the + point that this subroutine is called, the bit corresponding to + SYSMODE_SEG_DS_SS will be zero. After every instruction + except the segment override instructions, this bit (as well + as any bits indicating segment overrides) will be clear. So + if a SS access is needed, set this bit. Otherwise, DS access + occurs (unless any of the segment override bits are set). +****************************************************************************/ +unsigned decode_rm00_address( + int rm) +{ + unsigned offset; + + if (M.x86.mode & SYSMODE_PREFIX_ADDR) { + /* 32-bit addressing */ + switch (rm) { + case 0: + DECODE_PRINTF("[EAX]"); + return M.x86.R_EAX; + case 1: + DECODE_PRINTF("[ECX]"); + return M.x86.R_ECX; + case 2: + DECODE_PRINTF("[EDX]"); + return M.x86.R_EDX; + case 3: + DECODE_PRINTF("[EBX]"); + return M.x86.R_EBX; + case 4: + return decode_sib_address(0); + case 5: + offset = fetch_long_imm(); + DECODE_PRINTF2("[%08x]", offset); + return offset; + case 6: + DECODE_PRINTF("[ESI]"); + return M.x86.R_ESI; + case 7: + DECODE_PRINTF("[EDI]"); + return M.x86.R_EDI; + } + } else { + /* 16-bit addressing */ + switch (rm) { + case 0: + DECODE_PRINTF("[BX+SI]"); + return (M.x86.R_BX + M.x86.R_SI) & 0xffff; + case 1: + DECODE_PRINTF("[BX+DI]"); + return (M.x86.R_BX + M.x86.R_DI) & 0xffff; + case 2: + DECODE_PRINTF("[BP+SI]"); + M.x86.mode |= SYSMODE_SEG_DS_SS; + return (M.x86.R_BP + M.x86.R_SI) & 0xffff; + case 3: + DECODE_PRINTF("[BP+DI]"); + M.x86.mode |= SYSMODE_SEG_DS_SS; + return (M.x86.R_BP + M.x86.R_DI) & 0xffff; + case 4: + DECODE_PRINTF("[SI]"); + return M.x86.R_SI; + case 5: + DECODE_PRINTF("[DI]"); + return M.x86.R_DI; + case 6: + offset = fetch_word_imm(); + DECODE_PRINTF2("[%04x]", offset); + return offset; + case 7: + DECODE_PRINTF("[BX]"); + return M.x86.R_BX; + } + } + HALT_SYS(); + return 0; +} + +/**************************************************************************** +PARAMETERS: +rm - RM value to decode + +RETURNS: +Offset in memory for the address decoding + +REMARKS: +Return the offset given by mod=01 addressing. Also enables the +decoding of instructions. +****************************************************************************/ +unsigned decode_rm01_address( + int rm) +{ + int displacement; + + if (M.x86.mode & SYSMODE_PREFIX_ADDR) { + /* 32-bit addressing */ + if (rm != 4) + displacement = (s8)fetch_byte_imm(); + else + displacement = 0; + + switch (rm) { + case 0: + DECODE_PRINTF2("%d[EAX]", displacement); + return M.x86.R_EAX + displacement; + case 1: + DECODE_PRINTF2("%d[ECX]", displacement); + return M.x86.R_ECX + displacement; + case 2: + DECODE_PRINTF2("%d[EDX]", displacement); + return M.x86.R_EDX + displacement; + case 3: + DECODE_PRINTF2("%d[EBX]", displacement); + return M.x86.R_EBX + displacement; + case 4: { + int offset = decode_sib_address(1); + displacement = (s8)fetch_byte_imm(); + DECODE_PRINTF2("[%d]", displacement); + return offset + displacement; + } + case 5: + DECODE_PRINTF2("%d[EBP]", displacement); + return M.x86.R_EBP + displacement; + case 6: + DECODE_PRINTF2("%d[ESI]", displacement); + return M.x86.R_ESI + displacement; + case 7: + DECODE_PRINTF2("%d[EDI]", displacement); + return M.x86.R_EDI + displacement; + } + } else { + /* 16-bit addressing */ + displacement = (s8)fetch_byte_imm(); + switch (rm) { + case 0: + DECODE_PRINTF2("%d[BX+SI]", displacement); + return (M.x86.R_BX + M.x86.R_SI + displacement) & 0xffff; + case 1: + DECODE_PRINTF2("%d[BX+DI]", displacement); + return (M.x86.R_BX + M.x86.R_DI + displacement) & 0xffff; + case 2: + DECODE_PRINTF2("%d[BP+SI]", displacement); + M.x86.mode |= SYSMODE_SEG_DS_SS; + return (M.x86.R_BP + M.x86.R_SI + displacement) & 0xffff; + case 3: + DECODE_PRINTF2("%d[BP+DI]", displacement); + M.x86.mode |= SYSMODE_SEG_DS_SS; + return (M.x86.R_BP + M.x86.R_DI + displacement) & 0xffff; + case 4: + DECODE_PRINTF2("%d[SI]", displacement); + return (M.x86.R_SI + displacement) & 0xffff; + case 5: + DECODE_PRINTF2("%d[DI]", displacement); + return (M.x86.R_DI + displacement) & 0xffff; + case 6: + DECODE_PRINTF2("%d[BP]", displacement); + M.x86.mode |= SYSMODE_SEG_DS_SS; + return (M.x86.R_BP + displacement) & 0xffff; + case 7: + DECODE_PRINTF2("%d[BX]", displacement); + return (M.x86.R_BX + displacement) & 0xffff; + } + } + HALT_SYS(); + return 0; /* SHOULD NOT HAPPEN */ +} + +/**************************************************************************** +PARAMETERS: +rm - RM value to decode + +RETURNS: +Offset in memory for the address decoding + +REMARKS: +Return the offset given by mod=10 addressing. Also enables the +decoding of instructions. +****************************************************************************/ +unsigned decode_rm10_address( + int rm) +{ + if (M.x86.mode & SYSMODE_PREFIX_ADDR) { + int displacement; + + /* 32-bit addressing */ + if (rm != 4) + displacement = (s32)fetch_long_imm(); + else + displacement = 0; + + switch (rm) { + case 0: + DECODE_PRINTF2("%d[EAX]", displacement); + return M.x86.R_EAX + displacement; + case 1: + DECODE_PRINTF2("%d[ECX]", displacement); + return M.x86.R_ECX + displacement; + case 2: + DECODE_PRINTF2("%d[EDX]", displacement); + return M.x86.R_EDX + displacement; + case 3: + DECODE_PRINTF2("%d[EBX]", displacement); + return M.x86.R_EBX + displacement; + case 4: { + int offset = decode_sib_address(2); + displacement = (s32)fetch_long_imm(); + DECODE_PRINTF2("[%d]", displacement); + return offset + displacement; + } + case 5: + DECODE_PRINTF2("%d[EBP]", displacement); + return M.x86.R_EBP + displacement; + case 6: + DECODE_PRINTF2("%d[ESI]", displacement); + return M.x86.R_ESI + displacement; + case 7: + DECODE_PRINTF2("%d[EDI]", displacement); + return M.x86.R_EDI + displacement; + } + } else { + int displacement = (s16)fetch_word_imm(); + + /* 16-bit addressing */ + switch (rm) { + case 0: + DECODE_PRINTF2("%d[BX+SI]", displacement); + return (M.x86.R_BX + M.x86.R_SI + displacement) & 0xffff; + case 1: + DECODE_PRINTF2("%d[BX+DI]", displacement); + return (M.x86.R_BX + M.x86.R_DI + displacement) & 0xffff; + case 2: + DECODE_PRINTF2("%d[BP+SI]", displacement); + M.x86.mode |= SYSMODE_SEG_DS_SS; + return (M.x86.R_BP + M.x86.R_SI + displacement) & 0xffff; + case 3: + DECODE_PRINTF2("%d[BP+DI]", displacement); + M.x86.mode |= SYSMODE_SEG_DS_SS; + return (M.x86.R_BP + M.x86.R_DI + displacement) & 0xffff; + case 4: + DECODE_PRINTF2("%d[SI]", displacement); + return (M.x86.R_SI + displacement) & 0xffff; + case 5: + DECODE_PRINTF2("%d[DI]", displacement); + return (M.x86.R_DI + displacement) & 0xffff; + case 6: + DECODE_PRINTF2("%d[BP]", displacement); + M.x86.mode |= SYSMODE_SEG_DS_SS; + return (M.x86.R_BP + displacement) & 0xffff; + case 7: + DECODE_PRINTF2("%d[BX]", displacement); + return (M.x86.R_BX + displacement) & 0xffff; + } + } + HALT_SYS(); + return 0; /* SHOULD NOT HAPPEN */ +} + +/**************************************************************************** +PARAMETERS: +mod - modifier +rm - RM value to decode + +RETURNS: +Offset in memory for the address decoding, multiplexing calls to +the decode_rmXX_address functions + +REMARKS: +Return the offset given by "mod" addressing. +****************************************************************************/ + +unsigned decode_rmXX_address(int mod, int rm) +{ + if(mod == 0) + return decode_rm00_address(rm); + if(mod == 1) + return decode_rm01_address(rm); + return decode_rm10_address(rm); +} |