X86: Implemented and hooked in SCAS (scan string)

Fixed the asz assembler symbol.
Adjusted the condion checks to have appropriate options.
Implemented the SCAS microcode.
Attached SCAS into the decoder.

--HG--
extra : convert_revision : 17bf9ddae6bc2069e43b076f8f83c4e54fb7966c

src/arch/x86/insts/microregop.cc

@@ -112,8 +112,9 @@ namespace X86ISA
             panic("This condition is not implemented!");
           case ConditionTests::MSTRC:
             panic("This condition is not implemented!");
-          case ConditionTests::STRZnZF:
-            panic("This condition is not implemented!");
+          case ConditionTests::STRZnEZF:
+            return !ccflags.EZF & ccflags.ZF;
+                //And no interrupts or debug traps are waiting
           case ConditionTests::OF:
             return ccflags.OF;
           case ConditionTests::CF:
@@ -144,8 +145,9 @@ namespace X86ISA
             panic("This condition is not implemented!");
           case ConditionTests::NotMSTRC:
             panic("This condition is not implemented!");
-          case ConditionTests::NotSTRZnZF:
-            panic("This condition is not implemented!");
+          case ConditionTests::STRnZnEZF:
+            return !ccflags.EZF & !ccflags.ZF;
+                //And no interrupts or debug traps are waiting
           case ConditionTests::NotOF:
             return !ccflags.OF;
           case ConditionTests::NotCF:

src/arch/x86/insts/microregop.hh

@@ -73,7 +73,7 @@ namespace X86ISA
             MSTRZ,
             STRZ,
             MSTRC,
-            STRZnZF,
+            STRZnEZF,
             OF,
             CF,
             ZF,
@@ -91,7 +91,7 @@ namespace X86ISA
             NotMSTRZ,
             NotSTRZ,
             NotMSTRC,
-            NotSTRZnZF,
+            STRnZnEZF,
             NotOF,
             NotCF,
             NotZF,

src/arch/x86/isa/decoder/one_byte_opcodes.isa

@@ -342,8 +342,8 @@
             0x3: stos_Yv_rAX();
             0x4: lods_Al_Xb();
             0x5: lods_rAX_Xv();
-            0x6: scas_Yb_Al();
-            0x7: scas_Yv_rAX();
+            0x6: StringInst::SCAS(Yb);
+            0x7: StringInst::SCAS(Yv);
         }
         format Inst {
             0x16: MOV(Bb,Ib);

src/arch/x86/isa/insts/string/scan_string.py

@@ -53,16 +53,55 @@
 #
 # Authors: Gabe Black
 
-microcode = ""
-#let {{
-#    class SCAS(Inst):
-#	"GenFault ${new UnimpInstFault}"
-#    class SCASB(Inst):
-#	"GenFault ${new UnimpInstFault}"
-#    class SCASW(Inst):
-#	"GenFault ${new UnimpInstFault}"
-#    class SCASD(Inst):
-#	"GenFault ${new UnimpInstFault}"
-#    class SCASQ(Inst):
-#	"GenFault ${new UnimpInstFault}"
-#}};
+microcode = '''
+def macroop SCAS_M {
+    # Find the constant we need to either add or subtract from rdi
+    ruflag t0, 10
+    movi t2, t2, dsz, flags=(CEZF,), dataSize=asz
+    subi t3, t0, dsz, dataSize=asz
+    mov t2, t2, t3, flags=(nCEZF,), dataSize=asz
+
+    ld t1, es, [1, t0, rdi]
+    sub t0, t1, rax, flags=(OF, SF, ZF, AF, PF, CF)
+
+    add rdi, rdi, t2, dataSize=asz
+};
+
+#
+# Versions which have the rep prefix. These could benefit from some loop
+# unrolling.
+#
+
+def macroop SCAS_E_M {
+    # Find the constant we need to either add or subtract from rdi
+    ruflag t0, 10
+    movi t2, t2, dsz, flags=(CEZF,), dataSize=asz
+    subi t3, t0, dsz, dataSize=asz
+    mov t2, t2, t3, flags=(nCEZF,), dataSize=asz
+
+    ld t1, es, [1, t0, rdi]
+    sub t0, t1, rax, flags=(OF, SF, ZF, AF, PF, CF)
+
+    subi rcx, rcx, 1, flags=(EZF,), dataSize=asz
+    add rdi, rdi, t2, dataSize=asz
+    bri t0, 4, flags=(CSTRZnEZF,)
+    fault "NoFault"
+};
+
+def macroop SCAS_N_M {
+    # Find the constant we need to either add or subtract from rdi
+    ruflag t0, 10
+    movi t2, t2, dsz, flags=(CEZF,), dataSize=asz
+    subi t3, t0, dsz, dataSize=asz
+    mov t2, t2, t3, flags=(nCEZF,), dataSize=asz
+
+    ld t1, es, [1, t0, rdi]
+    sub t0, t1, rax, flags=(OF, SF, ZF, AF, PF, CF)
+
+    subi rcx, rcx, 1, flags=(EZF,), dataSize=asz
+    add rdi, rdi, t2, dataSize=asz
+    bri t0, 4, flags=(CSTRnZnEZF,)
+    fault "NoFault"
+};
+
+'''

src/arch/x86/isa/microasm.isa

@@ -89,7 +89,7 @@ let {{
         "index" : "env.index",
         "base" : "env.base",
         "dsz" : "env.dataSize",
-        "osz" : "env.operandSize",
+        "asz" : "env.addressSize",
         "ssz" : "env.stackSize"
     }
     assembler.symbols.update(symbols)
@@ -107,11 +107,13 @@ let {{
         assembler.symbols[flag] = flag + "Bit"
 
     for cond in ('True', 'False', 'ECF', 'EZF', 'SZnZF',
-                 'MSTRZ', 'STRZ', 'MSTRC', 'STRZnZF',
+                 'MSTRZ', 'STRZ', 'MSTRC',
                  'OF', 'CF', 'ZF', 'CvZF',
                  'SF', 'PF', 'SxOF', 'SxOvZF'):
         assembler.symbols["C%s" % cond] = "ConditionTests::%s" % cond
         assembler.symbols["nC%s" % cond] = "ConditionTests::Not%s" % cond
+    assembler.symbols["CSTRZnEZF"] = "ConditionTests::STRZnEZF"
+    assembler.symbols["CSTRnZnEZF"] = "ConditionTests::STRnZnEZF"
 
     assembler.symbols["CTrue"] = "ConditionTests::True"
     assembler.symbols["CFalse"] = "ConditionTests::False"