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-rw-r--r--3p/sst/x86.c194
1 files changed, 97 insertions, 97 deletions
diff --git a/3p/sst/x86.c b/3p/sst/x86.c
index 2bd59a6..6f69dcf 100644
--- a/3p/sst/x86.c
+++ b/3p/sst/x86.c
@@ -1,97 +1,97 @@
-/*
- * Copyright © 2024 Michael Smith <mikesmiffy128@gmail.com>
- *
- * 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 "../../intdef.h"
-#include "x86.h"
-
-static int mrmsib(const u8 *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 u8 *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
+/*
+ * Copyright © 2024 Michael Smith <mikesmiffy128@gmail.com>
+ *
+ * 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 "../../intdef.h"
+#include "x86.h"
+
+static int mrmsib(const u8 *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 u8 *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
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