2 * Copyright (c) 2012-2014 ARM Limited
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43 #include "arch/arm/decoder.hh"
45 #include "arch/arm/isa.hh"
46 #include "arch/arm/isa_traits.hh"
47 #include "arch/arm/utility.hh"
48 #include "base/trace.hh"
49 #include "debug/Decoder.hh"
54 GenericISA::BasicDecodeCache
Decoder::defaultCache
;
56 Decoder::Decoder(ISA
* isa
)
57 : data(0), fpscrLen(0), fpscrStride(0), decoderFlavour(isa
58 ? isa
->decoderFlavour()
78 // emi is typically ready, with some caveats below...
84 emi
.sevenAndFour
= bits(data
, 7) && bits(data
, 4);
85 emi
.isMisc
= (bits(data
, 24, 23) == 0x2 &&
89 DPRINTF(Decoder
, "Arm inst: %#x.\n", (uint64_t)emi
);
91 uint16_t word
= (data
>> (offset
* 8));
93 // A 32 bit thumb inst is half collected.
94 emi
.instBits
= emi
.instBits
| word
;
97 DPRINTF(Decoder
, "Second half of 32 bit Thumb: %#x.\n",
100 uint16_t highBits
= word
& 0xF800;
101 if (highBits
== 0xE800 || highBits
== 0xF000 ||
102 highBits
== 0xF800) {
103 // The start of a 32 bit thumb inst.
106 // We've got the whole thing.
107 emi
.instBits
= (data
>> 16) | (data
<< 16);
108 DPRINTF(Decoder
, "All of 32 bit Thumb: %#x.\n",
112 // We only have the first half word.
114 "First half of 32 bit Thumb.\n");
115 emi
.instBits
= (uint32_t)word
<< 16;
118 // emi not ready yet.
122 // A 16 bit thumb inst.
125 // Set the condition code field artificially.
126 emi
.condCode
= COND_UC
;
127 DPRINTF(Decoder
, "16 bit Thumb: %#x.\n",
129 if (bits(word
, 15, 8) == 0xbf &&
130 bits(word
, 3, 0) != 0x0) {
132 itBits
= bits(word
, 7, 0);
134 "IT detected, cond = %#x, mask = %#x\n",
135 itBits
.cond
, itBits
.mask
);
143 Decoder::consumeBytes(int numBytes
)
146 assert(offset
<= sizeof(MachInst
) || emi
.decoderFault
);
147 if (offset
== sizeof(MachInst
))
152 Decoder::moreBytes(const PCState
&pc
, Addr fetchPC
, MachInst inst
)
155 offset
= (fetchPC
>= pc
.instAddr()) ? 0 : pc
.instAddr() - fetchPC
;
156 emi
.thumb
= pc
.thumb();
157 emi
.aarch64
= pc
.aarch64();
158 emi
.fpscrLen
= fpscrLen
;
159 emi
.fpscrStride
= fpscrStride
;
161 const Addr
alignment(pc
.thumb() ? 0x1 : 0x3);
162 emi
.decoderFault
= static_cast<uint8_t>(
163 pc
.instAddr() & alignment
? DecoderFault::UNALIGNED
: DecoderFault::OK
);
170 Decoder::decode(ArmISA::PCState
&pc
)
175 const int inst_size((!emi
.thumb
|| emi
.bigThumb
) ? 4 : 2);
176 ExtMachInst
this_emi(emi
);
178 pc
.npc(pc
.pc() + inst_size
);
180 pc
.nextItstate(itBits
);
181 this_emi
.itstate
= pc
.itstate();
188 return decode(this_emi
, pc
.instAddr());