From 77ac95b9985f5669d6659bfb54728786d28c2ef0 Mon Sep 17 00:00:00 2001
From: chai <chaifix@163.com>
Date: Mon, 20 Jul 2020 09:42:30 +0800
Subject: *misc

---
 src/lua51/lopcodes.h | 33 +++++++++++++++++++++++----------
 1 file changed, 23 insertions(+), 10 deletions(-)

(limited to 'src/lua51/lopcodes.h')

diff --git a/src/lua51/lopcodes.h b/src/lua51/lopcodes.h
index 41224d6..8c0d1a8 100644
--- a/src/lua51/lopcodes.h
+++ b/src/lua51/lopcodes.h
@@ -34,13 +34,24 @@ enum OpMode {iABC, iABx, iAsBx};  /* basic instruction format */
 /*
 ** size and position of opcode arguments.
 */
-#define SIZE_C		9
-#define SIZE_B		9
-#define SIZE_Bx		(SIZE_C + SIZE_B)
-#define SIZE_A		8
+/*
+三种指令的格式
+iABC    B:9      C:9      A:8     Opcode:6
+iABx        Bx:18         A:8     Opcode:6
+iAsBx      sBx:18         A:8     Opcode:6
+注：sBx是signed BX
+寄存器就是相对于callinfo和lua_state的当前调用的base的某个偏移（即ABC值)
+*/
 
+//c 单个指令Instruction的每部分的大小
+// 9 + 9 + 8 + 6 = 32 bits
+#define SIZE_B		9 
+#define SIZE_C		9 
+#define SIZE_Bx		(SIZE_C + SIZE_B) 
+#define SIZE_A		8
 #define SIZE_OP		6
 
+//c 每个部分在Instruction中的偏移量，从低位到高位
 #define POS_OP		0
 #define POS_A		(POS_OP + SIZE_OP)
 #define POS_C		(POS_A + SIZE_A)
@@ -76,7 +87,7 @@ enum OpMode {iABC, iABx, iAsBx};  /* basic instruction format */
 /*
 ** the following macros help to manipulate instructions
 */
-
+//c 获取和设置Instruction中的某个部分
 #define GET_OPCODE(i)	(cast(OpCode, ((i)>>POS_OP) & MASK1(SIZE_OP,0)))
 #define SET_OPCODE(i,o)	((i) = (((i)&MASK0(SIZE_OP,POS_OP)) | \
 		((cast(Instruction, o)<<POS_OP)&MASK1(SIZE_OP,POS_OP))))
@@ -115,9 +126,11 @@ enum OpMode {iABC, iABx, iAsBx};  /* basic instruction format */
 ** Macros to operate RK indices
 */
 
+//c 高位为1时代表常数
 /* this bit 1 means constant (0 means register) */
 #define BITRK		(1 << (SIZE_B - 1))
 
+//c 检查x是不是常量，规定高位是1的话就是常量，去常量表里查，而不是寄存器
 /* test whether value is a constant */
 #define ISK(x)		((x) & BITRK)
 
@@ -241,12 +254,12 @@ OP_VARARG/*	A B	R(A), R(A+1), ..., R(A+B-1) = vararg		*/
 ** bit 6: instruction set register A
 ** bit 7: operator is a test
 */  
-
+//c 指令的参数格式
 enum OpArgMask {
-  OpArgN,  /* argument is not used */
-  OpArgU,  /* argument is used */
-  OpArgR,  /* argument is a register or a jump offset */
-  OpArgK   /* argument is a constant or register/constant */
+  OpArgN,  /* argument is not used */ // 未使用（没有座位R()和RK()的参数使用）
+  OpArgU,  /* argument is used */ // 使用的
+  OpArgR,  /* argument is a register or a jump offset */ // 寄存器、跳转偏移
+  OpArgK   /* argument is a constant or register/constant */ // 寄存器、常量
 };
 
 LUAI_DATA const lu_byte luaP_opmodes[NUM_OPCODES];
-- 
cgit v1.1-26-g67d0