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58 #ifndef __ARCH_X86_PREDECODER_HH__
59 #define __ARCH_X86_PREDECODER_HH__
61 #include "arch/x86/types.hh"
62 #include "base/bitfield.hh"
63 #include "base/misc.hh"
64 #include "base/trace.hh"
65 #include "sim/host.hh"
74 //These are defined and documented in predecoder_tables.cc
75 static const uint8_t Prefixes[256];
76 static const uint8_t UsesModRM[2][256];
77 static const uint8_t ImmediateType[2][256];
78 static const uint8_t SizeTypeToSize[3][10];
82 //The bytes to be predecoded
84 //The pc of the start of fetchChunk
86 //The pc the current instruction started at
88 //The offset into fetchChunk of current processing
90 //The extended machine instruction being generated
93 inline uint8_t getNextByte()
95 return (fetchChunk >> (offset * 8)) & 0xff;
98 void getImmediate(int &collected, uint64_t ¤t, int size)
100 //Figure out how many bytes we still need to get for the
102 int toGet = size - collected;
103 //Figure out how many bytes are left in our "buffer"
104 int remaining = sizeof(MachInst) - offset;
105 //Get as much as we need, up to the amount available.
106 toGet = toGet > remaining ? remaining : toGet;
108 //Shift the bytes we want to be all the way to the right
109 uint64_t partialImm = fetchChunk >> (offset * 8);
110 //Mask off what we don't want
111 partialImm &= mask(toGet * 8);
112 //Shift it over to overlay with our displacement.
113 partialImm <<= (immediateCollected * 8);
114 //Put it into our displacement
115 current |= partialImm;
116 //Update how many bytes we've collected.
121 inline void consumeByte()
124 assert(offset <= sizeof(MachInst));
125 if(offset == sizeof(MachInst))
129 inline void consumeBytes(int numBytes)
132 assert(offset <= sizeof(MachInst));
133 if(offset == sizeof(MachInst))
139 //State machine state
141 //Whether or not we're out of bytes
143 //Whether we've completed generating an ExtMachInst
145 //The size of the displacement value
146 int displacementSize;
147 //The size of the immediate value
149 //This is how much of any immediate value we've gotten. This is used
150 //for both the actual immediate and the displacement.
151 int immediateCollected;
161 //We should never get to this state. Getting here is an error.
167 //Functions to handle each of the states
168 State doPrefixState(uint8_t);
169 State doOpcodeState(uint8_t);
170 State doModRMState(uint8_t);
171 State doSIBState(uint8_t);
172 State doDisplacementState();
173 State doImmediateState();
176 Predecoder(ThreadContext * _tc) :
177 tc(_tc), basePC(0), origPC(0), offset(0),
178 outOfBytes(true), emiIsReady(false),
181 emi.mode.mode = LongMode;
182 emi.mode.submode = SixtyFourBitMode;
190 ThreadContext * getTC()
195 void setTC(ThreadContext * _tc)
202 //Use this to give data to the predecoder. This should be used
203 //when there is control flow.
204 void moreBytes(Addr pc, Addr fetchPC, MachInst data)
206 DPRINTF(Predecoder, "Getting more bytes.\n");
208 offset = (fetchPC >= pc) ? 0 : pc - fetchPC;
219 bool extMachInstReady()
224 //This returns a constant reference to the ExtMachInst to avoid a copy
225 const ExtMachInst & getExtMachInst()
235 "Calculating the instruction size: "
236 "basePC: %#x offset: %#x origPC: %#x\n",
237 basePC, offset, origPC);
238 return basePC + offset - origPC;
243 #endif // __ARCH_X86_PREDECODER_HH__