From 508878ff0a9e4cd8528727c41819bc2d70b33dd0 Mon Sep 17 00:00:00 2001 From: Michael Smith Date: Mon, 24 Nov 2025 03:19:49 +0000 Subject: Turn x86 stuff into a chunklet to help out SPT Quick unused header cleanup pass while we're at it. --- src/x86.c | 97 --------------------------------------------------------------- 1 file changed, 97 deletions(-) delete mode 100644 src/x86.c (limited to 'src/x86.c') diff --git a/src/x86.c b/src/x86.c deleted file mode 100644 index b017a70..0000000 --- a/src/x86.c +++ /dev/null @@ -1,97 +0,0 @@ -/* - * Copyright © Michael Smith - * - * Permission to use, copy, modify, and/or distribute this software for any - * purpose with or without fee is hereby granted, provided that the above - * copyright notice and this permission notice appear in all copies. - * - * THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH - * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY - * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, - * 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. - */ - -#include "intdefs.h" -#include "x86.h" - -static int mrmsib(const uchar *p, int addrlen) { - // I won't lie: I thought I almost understood this, but after bill walked me - // through correcting a bunch of wrong cases I now realise that I don't - // really understand it at all. If it helps, I used this as a reference: - // https://github.com/Nomade040/length-disassembler/blob/e8b34546/ldisasm.cpp#L14 - // But it's confusingly-written enough that the code I wrote before didn't - // work, so with any luck nobody will need to refer to it again and this is - // actually correct now. Fingers crossed. - if (addrlen == 4 || *p & 0xC0) { - int sib = addrlen == 4 && *p < 0xC0 && (*p & 7) == 4; - switch (*p & 0xC0) { - // disp8 - case 0x40: return 2 + sib; - // disp16/32 - case 0: - if ((*p & 7) != 5) { - // disp8/32 via SIB - if (sib && (p[1] & 7) == 5) return *p & 0x40 ? 3 : 6; - return 1 + sib; - } - case 0x80: return 1 + addrlen + sib; - } - } - if (addrlen == 2 && (*p & 0xC7) == 0x06) return 3; - return 1; // note: include the mrm itself in the byte count -} - -int x86_len(const void *insn_) { -#define CASES(name, _) case name: - const uchar *insn = insn_; - int pfxlen = 0, addrlen = 4, operandlen = 4; - -p: switch (*insn) { - case X86_PFX_ADSZ: addrlen = 2; goto P; // bit dumb sorry - case X86_PFX_OPSZ: operandlen = 2; -P: X86_SEG_PREFIXES(CASES) - case X86_PFX_LOCK: case X86_PFX_REPN: case X86_PFX_REP: - // instruction can only be 15 bytes. this could go over, oh well, - // just don't want to loop for 8 million years - if (++pfxlen == 14) return -1; - ++insn; - goto p; - } - - switch (*insn) { - X86_OPS_1BYTE_NO(CASES) return pfxlen + 1; - X86_OPS_1BYTE_I8(CASES) operandlen = 1; - X86_OPS_1BYTE_IW(CASES) return pfxlen + 1 + operandlen; - X86_OPS_1BYTE_IWI(CASES) return pfxlen + 1 + addrlen; - X86_OPS_1BYTE_I16(CASES) return pfxlen + 3; - X86_OPS_1BYTE_MRM(CASES) return pfxlen + 1 + mrmsib(insn + 1, addrlen); - X86_OPS_1BYTE_MRM_I8(CASES) operandlen = 1; - X86_OPS_1BYTE_MRM_IW(CASES) - return pfxlen + 1 + operandlen + mrmsib(insn + 1, addrlen); - case X86_ENTER: return pfxlen + 4; - case X86_CRAZY8: operandlen = 1; - case X86_CRAZYW: - if ((insn[1] & 0x38) >= 0x10) operandlen = 0; - return pfxlen + 1 + operandlen + mrmsib(insn + 1, addrlen); - case X86_2BYTE: ++insn; goto b2; - } - return -1; - -b2: switch (*insn) { - // we don't support any 3 byte ops for now, implement if ever needed... - case X86_3BYTE1: case X86_3BYTE2: case X86_3DNOW: return -1; - X86_OPS_2BYTE_NO(CASES) return pfxlen + 2; - X86_OPS_2BYTE_IW(CASES) return pfxlen + 2 + operandlen; - X86_OPS_2BYTE_MRM(CASES) return pfxlen + 2 + mrmsib(insn + 1, addrlen); - X86_OPS_2BYTE_MRM_I8(CASES) operandlen = 1; - return pfxlen + 2 + operandlen + mrmsib(insn + 1, addrlen); - } - - return -1; -#undef CASES -} - -// vi: sw=4 ts=4 noet tw=80 cc=80 -- cgit v1.2.3-54-g00ecf