From 80458e3288852dbbf0a34de7dcaf57c2e1898f7a Mon Sep 17 00:00:00 2001
From: Alexis Engelke <alexis.engelke@googlemail.com>
Date: Sun, 13 Jan 2019 14:26:26 +0100
Subject: [PATCH] Reduce space required by instruction width

---
 decode.c | 16 +++++++++-------
 decode.h |  4 ++--
 format.c |  4 ++--
 3 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/decode.c b/decode.c
index dd9bae8..efa52e7 100644
--- a/decode.c
+++ b/decode.c
@@ -567,35 +567,37 @@ decode(const uint8_t* buffer, int len, DecodeMode mode, Instr* instr)
         instr->segment = RI_DS;
     }
 
-    uint8_t op_size = 0;
+    uint8_t op_size_log = 0;
     if (desc->gp_size_8)
     {
-        op_size = 1;
+        op_size_log = 1;
     }
 #if defined(ARCH_X86_64)
     else if (prefixes & PREFIX_REXW)
     {
-        op_size = 8;
+        op_size_log = 4;
     }
 #endif
     else if (prefixes & PREFIX_OPSZ)
     {
-        op_size = 2;
+        op_size_log = 2;
     }
 #if defined(ARCH_X86_64)
     else if (mode == DECODE_64 && desc->gp_size_def64)
     {
-        op_size = 8;
+        op_size_log = 4;
     }
 #endif
     else
     {
-        op_size = 4;
+        op_size_log = 3;
     }
 
+    uint8_t op_size = (1 << op_size_log) >> 1;
+
     if (UNLIKELY(desc->gp_instr_width))
     {
-        instr->width = op_size;
+        instr->width = op_size_log;
     }
     else
     {
diff --git a/decode.h b/decode.h
index d800904..43ac1bf 100644
--- a/decode.h
+++ b/decode.h
@@ -117,7 +117,7 @@ struct Instr
     uint16_t type;
     struct Operand operands[4];
     uint8_t segment : 3;
-    uint8_t width : 5;
+    uint8_t width : 3;
 
     /**
      * Encoded as 1 << (scale - 1)  **or**  no scaled register at all if zero.
@@ -136,7 +136,7 @@ struct Instr
 typedef struct Instr Instr;
 
 #define INSTR_SEGMENT(instr) ((instr)->segment)
-#define INSTR_WIDTH(instr) ((instr)->width)
+#define INSTR_WIDTH(instr) ((1 << (instr)->width) >> 1)
 #define INSTR_HAS_REP(instr) ((instr)->prefixes & PREFIX_REP)
 #define INSTR_HAS_REPNZ(instr) ((instr)->prefixes & PREFIX_REPNZ)
 #define INSTR_HAS_LOCK(instr) ((instr)->prefixes & PREFIX_LOCK)
diff --git a/format.c b/format.c
index 79325ad..9838dad 100644
--- a/format.c
+++ b/format.c
@@ -83,10 +83,10 @@ instr_format(const Instr* instr, char buffer[128])
         *(cur++) = *(mnemonic++);
     }
 
-    if (instr->width != 0)
+    if (INSTR_WIDTH(instr))
     {
         *(cur++) = '_';
-        instr_format_decimal(&cur, instr->width);
+        instr_format_decimal(&cur, INSTR_WIDTH(instr));
     }
 
     for (int i = 0; i < 4; i++)