From 63cb4fbbb961da133c68865845eaf22d9b876700 Mon Sep 17 00:00:00 2001
From: chai <chaifix@163.com>
Date: Sun, 27 Sep 2020 20:31:53 +0800
Subject: *misc

---
 src/lua51/lcode.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

(limited to 'src/lua51/lcode.c')

diff --git a/src/lua51/lcode.c b/src/lua51/lcode.c
index 8f25b06..640f107 100644
--- a/src/lua51/lcode.c
+++ b/src/lua51/lcode.c
@@ -56,11 +56,12 @@ void luaK_nil (FuncState *fs, int from, int n) {
 }
 
 
+//c 生成jump指令
 int luaK_jump (FuncState *fs) {
   int jpc = fs->jpc;  /* save list of jumps to here */
   int j;
   fs->jpc = NO_JUMP;
-  j = luaK_codeAsBx(fs, OP_JMP, 0, NO_JUMP);
+  j = luaK_codeAsBx(fs, OP_JMP, 0, NO_JUMP); // 生成OP_JUMP指令
   luaK_concat(fs, &j, jpc);  /* keep them on hold */
   return j;
 }
@@ -196,6 +197,7 @@ void luaK_concat (FuncState *fs, int *l1, int l2) {
 }
 
 
+//c 
 void luaK_checkstack (FuncState *fs, int n) {
   int newstack = fs->freereg + n;
   if (newstack > fs->f->maxstacksize) {
@@ -344,7 +346,7 @@ static int code_label (FuncState *fs, int A, int b, int jump) {
   return luaK_codeABC(fs, OP_LOADBOOL, A, b, jump);
 }
 
-
+//c! 根据不同的表达式类型，比如NIL，TRUE,NUMBER等生成对应的字节码
 static void discharge2reg (FuncState *fs, expdesc *e, int reg) {
   luaK_dischargevars(fs, e);
   switch (e->k) {
@@ -360,7 +362,7 @@ static void discharge2reg (FuncState *fs, expdesc *e, int reg) {
       luaK_codeABx(fs, OP_LOADK, reg, e->u.s.info);
       break;
     }
-    case VKNUM: {
+    case VKNUM: { // 将常量设置到寄存器
       luaK_codeABx(fs, OP_LOADK, reg, luaK_numberK(fs, e->u.nval));
       break;
     }
@@ -416,10 +418,11 @@ static void exp2reg (FuncState *fs, expdesc *e, int reg) {
 }
 
 
+//c! 根据expdesc结构生成字节码
 void luaK_exp2nextreg (FuncState *fs, expdesc *e) {
-  luaK_dischargevars(fs, e);
-  freeexp(fs, e);
-  luaK_reserveregs(fs, 1);
+  luaK_dischargevars(fs, e); // 根据变量的作用域来决定这个变量是否需要重定向，即VNONRELOC或VRELOC
+  freeexp(fs, e); // 如果不需要重定向，释放expdesc寄存器
+  luaK_reserveregs(fs, 1); //申请一个寄存器
   exp2reg(fs, e, fs->freereg - 1);
 }
 
@@ -791,7 +794,7 @@ void luaK_fixline (FuncState *fs, int line) {
 }
 
 
-//c 指令生成
+//c 指令生成的唯一入口
 static int luaK_code (FuncState *fs, Instruction i, int line) {
   Proto *f = fs->f;
   dischargejpc(fs);  /* `pc' will change */
-- 
cgit v1.1-26-g67d0