no more 'getBMode'-'getCMode' (imprecise + we will need more space

for op mode) + better control of op modes

lcode.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lcode.c,v 2.124 2017/09/26 17:10:49 roberto Exp roberto $
+** $Id: lcode.c,v 2.125 2017/09/26 18:14:45 roberto Exp roberto $
 ** Code generator for Lua
 ** See Copyright Notice in lua.h
 */
@@ -367,8 +367,6 @@ static int luaK_code (FuncState *fs, Instruction i) {
 */
 int luaK_codeABC (FuncState *fs, OpCode o, int a, int b, int c) {
   lua_assert(getOpMode(o) == iABC);
-  lua_assert(getBMode(o) != OpArgN || b == 0);
-  lua_assert(getCMode(o) != OpArgN || c == 0);
   lua_assert(a <= MAXARG_A && b <= MAXARG_B && c <= MAXARG_C);
   return luaK_code(fs, CREATE_ABC(o, a, b, c));
 }
@@ -378,13 +376,23 @@ int luaK_codeABC (FuncState *fs, OpCode o, int a, int b, int c) {
 ** Format and emit an 'iABx' instruction.
 */
 int luaK_codeABx (FuncState *fs, OpCode o, int a, unsigned int bc) {
-  lua_assert(getOpMode(o) == iABx || getOpMode(o) == iAsBx);
-  lua_assert(getCMode(o) == OpArgN);
+  lua_assert(getOpMode(o) == iABx);
   lua_assert(a <= MAXARG_A && bc <= MAXARG_Bx);
   return luaK_code(fs, CREATE_ABx(o, a, bc));
 }
 
 
+/*
+** Format and emit an 'iAsBx' instruction.
+*/
+int luaK_codeAsBx (FuncState *fs, OpCode o, int a, int bc) {
+  unsigned int b = bc + MAXARG_sBx;
+  lua_assert(getOpMode(o) == iAsBx);
+  lua_assert(a <= MAXARG_A && b <= MAXARG_Bx);
+  return luaK_code(fs, CREATE_ABx(o, a, b));
+}
+
+
 /*
 ** Emit an "extra argument" instruction (format 'iAx')
 */

lcode.h

@@ -1,5 +1,5 @@
 /*
-** $Id: lcode.h,v 1.65 2017/04/20 19:53:55 roberto Exp roberto $
+** $Id: lcode.h,v 1.66 2017/09/13 19:50:08 roberto Exp roberto $
 ** Code generator for Lua
 ** See Copyright Notice in lua.h
 */
@@ -43,13 +43,13 @@ typedef enum UnOpr { OPR_MINUS, OPR_BNOT, OPR_NOT, OPR_LEN, OPR_NOUNOPR } UnOpr;
 /* get (pointer to) instruction of given 'expdesc' */
 #define getinstruction(fs,e)	((fs)->f->code[(e)->u.info])
 
-#define luaK_codeAsBx(fs,o,A,sBx)	luaK_codeABx(fs,o,A,(sBx)+MAXARG_sBx)
 
 #define luaK_setmultret(fs,e)	luaK_setreturns(fs, e, LUA_MULTRET)
 
 #define luaK_jumpto(fs,t)	luaK_patchlist(fs, luaK_jump(fs), t)
 
 LUAI_FUNC int luaK_codeABx (FuncState *fs, OpCode o, int A, unsigned int Bx);
+LUAI_FUNC int luaK_codeAsBx (FuncState *fs, OpCode o, int A, int Bx);
 LUAI_FUNC int luaK_codeABC (FuncState *fs, OpCode o, int A, int B, int C);
 LUAI_FUNC void luaK_fixline (FuncState *fs, int line);
 LUAI_FUNC void luaK_nil (FuncState *fs, int from, int n);

lopcodes.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lopcodes.c,v 1.63 2017/09/19 18:38:14 roberto Exp roberto $
+** $Id: lopcodes.c,v 1.64 2017/09/26 18:14:45 roberto Exp roberto $
 ** Opcodes for Lua virtual machine
 ** See Copyright Notice in lua.h
 */
@@ -77,64 +77,62 @@ LUAI_DDEF const char *const luaP_opnames[NUM_OPCODES+1] = {
 };
 
 
-#define opmode(t,a,b,c,m) (((t)<<7) | ((a)<<6) | ((b)<<4) | ((c)<<2) | (m))
-
 LUAI_DDEF const lu_byte luaP_opmodes[NUM_OPCODES] = {
-/*       T  A    B       C     mode		   opcode	*/
-  opmode(0, 1, OpArgR, OpArgN, iABC)		/* OP_MOVE */
- ,opmode(0, 1, OpArgU, OpArgN, iAsBx)		/* OP_LOADI */
- ,opmode(0, 1, OpArgU, OpArgN, iAsBx)		/* OP_LOADF */
- ,opmode(0, 1, OpArgK, OpArgN, iABx)		/* OP_LOADK */
- ,opmode(0, 1, OpArgN, OpArgN, iABx)		/* OP_LOADKX */
- ,opmode(0, 1, OpArgU, OpArgU, iABC)		/* OP_LOADBOOL */
- ,opmode(0, 1, OpArgU, OpArgN, iABC)		/* OP_LOADNIL */
- ,opmode(0, 1, OpArgU, OpArgN, iABC)		/* OP_GETUPVAL */
- ,opmode(0, 0, OpArgU, OpArgN, iABC)		/* OP_SETUPVAL */
- ,opmode(0, 1, OpArgU, OpArgK, iABC)		/* OP_GETTABUP */
- ,opmode(0, 1, OpArgR, OpArgR, iABC)		/* OP_GETTABLE */
- ,opmode(0, 1, OpArgR, OpArgU, iABC)		/* OP_GETI */
- ,opmode(0, 1, OpArgR, OpArgK, iABC)		/* OP_GETFIELD */
- ,opmode(0, 0, OpArgK, OpArgK, iABC)		/* OP_SETTABUP */
- ,opmode(0, 0, OpArgR, OpArgK, iABC)		/* OP_SETTABLE */
- ,opmode(0, 0, OpArgU, OpArgK, iABC)		/* OP_SETI */
- ,opmode(0, 0, OpArgK, OpArgK, iABC)		/* OP_SETFIELD */
- ,opmode(0, 1, OpArgU, OpArgU, iABC)		/* OP_NEWTABLE */
- ,opmode(0, 1, OpArgR, OpArgK, iABC)		/* OP_SELF */
- ,opmode(0, 1, OpArgR, OpArgU, iABC)		/* OP_ADDI */
- ,opmode(0, 1, OpArgR, OpArgR, iABC)		/* OP_ADD */
- ,opmode(0, 1, OpArgR, OpArgR, iABC)		/* OP_SUB */
- ,opmode(0, 1, OpArgR, OpArgR, iABC)		/* OP_MUL */
- ,opmode(0, 1, OpArgR, OpArgR, iABC)		/* OP_MOD */
- ,opmode(0, 1, OpArgR, OpArgR, iABC)		/* OP_POW */
- ,opmode(0, 1, OpArgR, OpArgR, iABC)		/* OP_DIV */
- ,opmode(0, 1, OpArgR, OpArgR, iABC)		/* OP_IDIV */
- ,opmode(0, 1, OpArgR, OpArgR, iABC)		/* OP_BAND */
- ,opmode(0, 1, OpArgR, OpArgR, iABC)		/* OP_BOR */
- ,opmode(0, 1, OpArgR, OpArgR, iABC)		/* OP_BXOR */
- ,opmode(0, 1, OpArgR, OpArgR, iABC)		/* OP_SHL */
- ,opmode(0, 1, OpArgR, OpArgR, iABC)		/* OP_SHR */
- ,opmode(0, 1, OpArgR, OpArgN, iABC)		/* OP_UNM */
- ,opmode(0, 1, OpArgR, OpArgN, iABC)		/* OP_BNOT */
- ,opmode(0, 1, OpArgR, OpArgN, iABC)		/* OP_NOT */
- ,opmode(0, 1, OpArgR, OpArgN, iABC)		/* OP_LEN */
- ,opmode(0, 1, OpArgR, OpArgR, iABC)		/* OP_CONCAT */
- ,opmode(0, 0, OpArgN, OpArgN, iABC)		/* OP_CLOSE */
- ,opmode(0, 0, OpArgU, OpArgN, iAsBx)		/* OP_JMP */
- ,opmode(1, 0, OpArgR, OpArgR, iABC)		/* OP_EQ */
- ,opmode(1, 0, OpArgR, OpArgR, iABC)		/* OP_LT */
- ,opmode(1, 0, OpArgR, OpArgR, iABC)		/* OP_LE */
- ,opmode(1, 0, OpArgN, OpArgU, iABC)		/* OP_TEST */
- ,opmode(1, 1, OpArgR, OpArgU, iABC)		/* OP_TESTSET */
- ,opmode(0, 1, OpArgU, OpArgU, iABC)		/* OP_CALL */
- ,opmode(0, 1, OpArgU, OpArgU, iABC)		/* OP_TAILCALL */
- ,opmode(0, 0, OpArgU, OpArgN, iABC)		/* OP_RETURN */
- ,opmode(0, 1, OpArgR, OpArgN, iABx)		/* OP_FORLOOP */
- ,opmode(0, 1, OpArgR, OpArgN, iABx)		/* OP_FORPREP */
- ,opmode(0, 0, OpArgN, OpArgU, iABC)		/* OP_TFORCALL */
- ,opmode(0, 1, OpArgR, OpArgN, iABx)		/* OP_TFORLOOP */
- ,opmode(0, 0, OpArgU, OpArgU, iABC)		/* OP_SETLIST */
- ,opmode(0, 1, OpArgU, OpArgN, iABx)		/* OP_CLOSURE */
- ,opmode(0, 1, OpArgU, OpArgR, iABC)		/* OP_VARARG */
- ,opmode(0, 0, OpArgU, OpArgU, iAx)		/* OP_EXTRAARG */
+/*       T  A    mode		   opcode	*/
+  opmode(0, 1, iABC)		/* OP_MOVE */
+ ,opmode(0, 1, iAsBx)		/* OP_LOADI */
+ ,opmode(0, 1, iAsBx)		/* OP_LOADF */
+ ,opmode(0, 1, iABx)		/* OP_LOADK */
+ ,opmode(0, 1, iABx)		/* OP_LOADKX */
+ ,opmode(0, 1, iABC)		/* OP_LOADBOOL */
+ ,opmode(0, 1, iABC)		/* OP_LOADNIL */
+ ,opmode(0, 1, iABC)		/* OP_GETUPVAL */
+ ,opmode(0, 0, iABC)		/* OP_SETUPVAL */
+ ,opmode(0, 1, iABC)		/* OP_GETTABUP */
+ ,opmode(0, 1, iABC)		/* OP_GETTABLE */
+ ,opmode(0, 1, iABC)		/* OP_GETI */
+ ,opmode(0, 1, iABC)		/* OP_GETFIELD */
+ ,opmode(0, 0, iABC)		/* OP_SETTABUP */
+ ,opmode(0, 0, iABC)		/* OP_SETTABLE */
+ ,opmode(0, 0, iABC)		/* OP_SETI */
+ ,opmode(0, 0, iABC)		/* OP_SETFIELD */
+ ,opmode(0, 1, iABC)		/* OP_NEWTABLE */
+ ,opmode(0, 1, iABC)		/* OP_SELF */
+ ,opmode(0, 1, iABC)		/* OP_ADDI */
+ ,opmode(0, 1, iABC)		/* OP_ADD */
+ ,opmode(0, 1, iABC)		/* OP_SUB */
+ ,opmode(0, 1, iABC)		/* OP_MUL */
+ ,opmode(0, 1, iABC)		/* OP_MOD */
+ ,opmode(0, 1, iABC)		/* OP_POW */
+ ,opmode(0, 1, iABC)		/* OP_DIV */
+ ,opmode(0, 1, iABC)		/* OP_IDIV */
+ ,opmode(0, 1, iABC)		/* OP_BAND */
+ ,opmode(0, 1, iABC)		/* OP_BOR */
+ ,opmode(0, 1, iABC)		/* OP_BXOR */
+ ,opmode(0, 1, iABC)		/* OP_SHL */
+ ,opmode(0, 1, iABC)		/* OP_SHR */
+ ,opmode(0, 1, iABC)		/* OP_UNM */
+ ,opmode(0, 1, iABC)		/* OP_BNOT */
+ ,opmode(0, 1, iABC)		/* OP_NOT */
+ ,opmode(0, 1, iABC)		/* OP_LEN */
+ ,opmode(0, 1, iABC)		/* OP_CONCAT */
+ ,opmode(0, 0, iABC)		/* OP_CLOSE */
+ ,opmode(0, 0, iAsBx)		/* OP_JMP */
+ ,opmode(1, 0, iABC)		/* OP_EQ */
+ ,opmode(1, 0, iABC)		/* OP_LT */
+ ,opmode(1, 0, iABC)		/* OP_LE */
+ ,opmode(1, 0, iABC)		/* OP_TEST */
+ ,opmode(1, 1, iABC)		/* OP_TESTSET */
+ ,opmode(0, 1, iABC)		/* OP_CALL */
+ ,opmode(0, 1, iABC)		/* OP_TAILCALL */
+ ,opmode(0, 0, iABC)		/* OP_RETURN */
+ ,opmode(0, 1, iABx)		/* OP_FORLOOP */
+ ,opmode(0, 1, iABx)		/* OP_FORPREP */
+ ,opmode(0, 0, iABC)		/* OP_TFORCALL */
+ ,opmode(0, 1, iABx)		/* OP_TFORLOOP */
+ ,opmode(0, 0, iABC)		/* OP_SETLIST */
+ ,opmode(0, 1, iABx)		/* OP_CLOSURE */
+ ,opmode(0, 1, iABC)		/* OP_VARARG */
+ ,opmode(0, 0, iAx)		/* OP_EXTRAARG */
 };
 

lopcodes.h

@@ -1,5 +1,5 @@
 /*
-** $Id: lopcodes.h,v 1.160 2017/09/19 18:38:14 roberto Exp roberto $
+** $Id: lopcodes.h,v 1.161 2017/09/26 18:14:45 roberto Exp roberto $
 ** Opcodes for Lua virtual machine
 ** See Copyright Notice in lua.h
 */
@@ -89,6 +89,9 @@ enum OpMode {iABC, iABx, iAsBx, iAx};  /* basic instruction format */
 #define SET_OPCODE(i,o)	((i) = (((i)&MASK0(SIZE_OP,POS_OP)) | \
 		((cast(Instruction, o)<<POS_OP)&MASK1(SIZE_OP,POS_OP))))
 
+#define checkopm(i,m)	(getOpMode(GET_OPCODE(i)) == m)
+
+
 #define getarg(i,pos,size)	(cast(int, ((i)>>(pos)) & MASK1(size,0)))
 #define setarg(i,v,pos,size)	((i) = (((i)&MASK0(size,pos)) | \
                 ((cast(Instruction, v)<<pos)&MASK1(size,pos))))
@@ -96,25 +99,28 @@ enum OpMode {iABC, iABx, iAsBx, iAx};  /* basic instruction format */
 #define GETARG_A(i)	getarg(i, POS_A, SIZE_A)
 #define SETARG_A(i,v)	setarg(i, v, POS_A, SIZE_A)
 
-#define GETARG_B(i)	getarg(i, POS_B, SIZE_B)
+#define GETARG_B(i)	check_exp(checkopm(i, iABC), getarg(i, POS_B, SIZE_B))
 #define SETARG_B(i,v)	setarg(i, v, POS_B, SIZE_B)
 
-#define GETARG_Br(i)	getarg(i, POS_B, SIZE_B - 1)
+#define GETARG_Br(i)  \
+	check_exp(checkopm(i, iABC), getarg(i, POS_B, SIZE_B - 1))
 #define GETARG_Bk(i)	getarg(i, (POS_B + SIZE_B - 1), 1)
 
-#define GETARG_C(i)	getarg(i, POS_C, SIZE_C)
+#define GETARG_C(i)	check_exp(checkopm(i, iABC), getarg(i, POS_C, SIZE_C))
 #define SETARG_C(i,v)	setarg(i, v, POS_C, SIZE_C)
 
-#define GETARG_Cr(i)	getarg(i, POS_C, SIZE_C - 1)
+#define GETARG_Cr(i)  \
+	check_exp(checkopm(i, iABC), getarg(i, POS_C, SIZE_C - 1))
 #define GETARG_Ck(i)	getarg(i, (POS_C + SIZE_C - 1), 1)
 
-#define GETARG_Bx(i)	getarg(i, POS_Bx, SIZE_Bx)
+#define GETARG_Bx(i)	check_exp(checkopm(i, iABx), getarg(i, POS_Bx, SIZE_Bx))
 #define SETARG_Bx(i,v)	setarg(i, v, POS_Bx, SIZE_Bx)
 
-#define GETARG_Ax(i)	getarg(i, POS_Ax, SIZE_Ax)
+#define GETARG_Ax(i)	check_exp(checkopm(i, iAx), getarg(i, POS_Ax, SIZE_Ax))
 #define SETARG_Ax(i,v)	setarg(i, v, POS_Ax, SIZE_Ax)
 
-#define GETARG_sBx(i)	(GETARG_Bx(i)-MAXARG_sBx)
+#define GETARG_sBx(i)  \
+	check_exp(checkopm(i, iAsBx), getarg(i, POS_Bx, SIZE_Bx) - MAXARG_sBx)
 #define SETARG_sBx(i,b)	SETARG_Bx((i),cast(unsigned int, (b)+MAXARG_sBx))
 
 
@@ -160,8 +166,8 @@ enum OpMode {iABC, iABx, iAsBx, iAx};  /* basic instruction format */
 
 /*
 ** R(x) - register
-** Kst(x) - constant (in constant table)
-** RK(x) == if ISK(x) then Kst(INDEXK(x)) else R(x)
+** K(x) - constant (in constant table)
+** RK(x) == if ISK(x) then K(INDEXK(x)) else R(x)
 */
 
 
@@ -176,8 +182,8 @@ name		args	description
 OP_MOVE,/*	A B	R(A) := R(B)					*/
 OP_LOADI,/*	A sBx	R(A) := sBx					*/
 OP_LOADF,/*	A sBx	R(A) := (lua_Number)sBx				*/
-OP_LOADK,/*	A Bx	R(A) := Kst(Bx)					*/
-OP_LOADKX,/*	A 	R(A) := Kst(extra arg)				*/
+OP_LOADK,/*	A Bx	R(A) := K(Bx)					*/
+OP_LOADKX,/*	A 	R(A) := K(extra arg)				*/
 OP_LOADBOOL,/*	A B C	R(A) := (Bool)B; if (C) pc++			*/
 OP_LOADNIL,/*	A B	R(A), R(A+1), ..., R(A+B) := nil		*/
 OP_GETUPVAL,/*	A B	R(A) := UpValue[B]				*/
@@ -186,7 +192,7 @@ OP_SETUPVAL,/*	A B	UpValue[B] := R(A)				*/
 OP_GETTABUP,/*	A B C	R(A) := UpValue[B][K(C):string]			*/
 OP_GETTABLE,/*	A B C	R(A) := R(B)[R(C)]				*/
 OP_GETI,/*	A B C	R(A) := R(B)[C]					*/
-OP_GETFIELD,/*	A B C	R(A) := R(B)[Kst(C):string]			*/
+OP_GETFIELD,/*	A B C	R(A) := R(B)[K(C):string]			*/
 
 OP_SETTABUP,/*	A B C	UpValue[A][K(B):string] := RK(C)		*/
 OP_SETTABLE,/*	A B C	R(A)[R(B)] := RK(C)				*/
@@ -277,27 +283,18 @@ OP_EXTRAARG/*	Ax	extra (larger) argument for previous opcode	*/
 
 /*
 ** masks for instruction properties. The format is:
-** bits 0-1: op mode
-** bits 2-3: C arg mode
-** bits 4-5: B arg mode
-** bit 6: instruction set register A
-** bit 7: operator is a test (next instruction must be a jump)
+** bits 0-2: op mode
+** bit 3: instruction set register A
+** bit 4: operator is a test (next instruction must be a jump)
 */
 
-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 */
-};
-
 LUAI_DDEC const lu_byte luaP_opmodes[NUM_OPCODES];
 
-#define getOpMode(m)	(cast(enum OpMode, luaP_opmodes[m] & 3))
-#define getBMode(m)	(cast(enum OpArgMask, (luaP_opmodes[m] >> 4) & 3))
-#define getCMode(m)	(cast(enum OpArgMask, (luaP_opmodes[m] >> 2) & 3))
-#define testAMode(m)	(luaP_opmodes[m] & (1 << 6))
-#define testTMode(m)	(luaP_opmodes[m] & (1 << 7))
+#define getOpMode(m)	(cast(enum OpMode, luaP_opmodes[m] & 7))
+#define testAMode(m)	(luaP_opmodes[m] & (1 << 3))
+#define testTMode(m)	(luaP_opmodes[m] & (1 << 4))
+
+#define opmode(t,a,m) (((t)<<4) | ((a)<<3) | (m))
 
 
 LUAI_DDEC const char *const luaP_opnames[NUM_OPCODES+1];  /* opcode names */

lparser.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lparser.c,v 2.164 2017/08/14 18:33:14 roberto Exp roberto $
+** $Id: lparser.c,v 2.165 2017/09/13 19:50:08 roberto Exp roberto $
 ** Lua Parser
 ** See Copyright Notice in lua.h
 */
@@ -1373,7 +1373,7 @@ static void forbody (LexState *ls, int base, int line, int nvars, int isnum) {
     luaK_patchtohere(fs, prep);
     luaK_codeABC(fs, OP_TFORCALL, base, 0, nvars);
     luaK_fixline(fs, line);
-    endfor = luaK_codeAsBx(fs, OP_TFORLOOP, base + 2, NO_JUMP);
+    endfor = luaK_codeABx(fs, OP_TFORLOOP, base + 2, 0);
   }
   fixforjump(fs, endfor, prep + 1, 1);
   luaK_fixline(fs, line);

lvm.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lvm.c,v 2.294 2017/09/26 18:14:45 roberto Exp roberto $
+** $Id: lvm.c,v 2.295 2017/09/27 18:59:08 roberto Exp roberto $
 ** Lua virtual machine
 ** See Copyright Notice in lua.h
 */
@@ -733,14 +733,13 @@ void luaV_finishOp (lua_State *L) {
 
 
 #define RA(i)	(base+GETARG_A(i))
-#define RB(i)	check_exp(getBMode(GET_OPCODE(i)) == OpArgR, base+GETARG_Br(i))
+#define RB(i)	(base+GETARG_Br(i))
 #define vRB(i)	s2v(RB(i))
-#define KB(i)	check_exp(getBMode(GET_OPCODE(i)) == OpArgK, k+GETARG_B(i))
-#define RC(i)	check_exp(getCMode(GET_OPCODE(i)) == OpArgR, base+GETARG_C(i))
+#define KB(i)	(k+GETARG_B(i))
+#define RC(i)	(base+GETARG_C(i))
 #define vRC(i)	s2v(RC(i))
-#define KC(i)	check_exp(getCMode(GET_OPCODE(i)) == OpArgK, k+GETARG_C(i))
-#define RKC(i)	check_exp(getCMode(GET_OPCODE(i)) == OpArgK, \
-	(GETARG_Ck(i)) ? k + GETARG_Cr(i) : s2v(base + GETARG_Cr(i)))
+#define KC(i)	(k+GETARG_C(i))
+#define RKC(i)	((GETARG_Ck(i)) ? k + GETARG_Cr(i) : s2v(base + GETARG_Cr(i)))
 
 
 
@@ -834,8 +833,7 @@ void luaV_execute (lua_State *L) {
       }
       vmcase(OP_LOADKX) {
         TValue *rb;
-        lua_assert(GET_OPCODE(*pc) == OP_EXTRAARG);
-        rb = k + GETARG_Ax(*pc++);
+        rb = k + GETARG_Ax(*pc); pc++;
         setobj2s(L, ra, rb);
         vmbreak;
       }
@@ -1409,8 +1407,7 @@ void luaV_execute (lua_State *L) {
         Table *h;
         if (n == 0) n = cast_int(L->top - ra) - 1;
         if (c == 0) {
-          lua_assert(GET_OPCODE(*pc) == OP_EXTRAARG);
-          c = GETARG_Ax(*pc++);
+          c = GETARG_Ax(*pc); pc++;
         }
         h = hvalue(s2v(ra));
         last = ((c-1)*LFIELDS_PER_FLUSH) + n;