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c906108c SS |
1 | /* thumbemu.c -- Thumb instruction emulation. |
2 | Copyright (C) 1996, Cygnus Software Technologies Ltd. | |
3 | ||
4 | This program is free software; you can redistribute it and/or modify | |
5 | it under the terms of the GNU General Public License as published by | |
6 | the Free Software Foundation; either version 2 of the License, or | |
7 | (at your option) any later version. | |
8 | ||
9 | This program is distributed in the hope that it will be useful, | |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | GNU General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU General Public License | |
15 | along with this program; if not, write to the Free Software | |
16 | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ | |
17 | ||
18 | /* We can provide simple Thumb simulation by decoding the Thumb | |
19 | instruction into its corresponding ARM instruction, and using the | |
20 | existing ARM simulator. */ | |
21 | ||
dfcd3bfb | 22 | #ifndef MODET /* required for the Thumb instruction support */ |
c906108c SS |
23 | #if 1 |
24 | #error "MODET needs to be defined for the Thumb world to work" | |
25 | #else | |
26 | #define MODET (1) | |
27 | #endif | |
28 | #endif | |
29 | ||
30 | #include "armdefs.h" | |
31 | #include "armemu.h" | |
7a292a7a | 32 | #include "armos.h" |
c906108c SS |
33 | |
34 | /* Decode a 16bit Thumb instruction. The instruction is in the low | |
35 | 16-bits of the tinstr field, with the following Thumb instruction | |
36 | held in the high 16-bits. Passing in two Thumb instructions allows | |
37 | easier simulation of the special dual BL instruction. */ | |
38 | ||
dfcd3bfb JM |
39 | tdstate ARMul_ThumbDecode (state, pc, tinstr, ainstr) |
40 | ARMul_State * | |
41 | state; | |
42 | ARMword | |
43 | pc; | |
44 | ARMword | |
45 | tinstr; | |
46 | ARMword * | |
47 | ainstr; | |
c906108c | 48 | { |
dfcd3bfb | 49 | tdstate valid = t_decoded; /* default assumes a valid instruction */ |
c906108c | 50 | ARMword next_instr; |
dfcd3bfb | 51 | |
c906108c SS |
52 | if (state->bigendSig) |
53 | { | |
54 | next_instr = tinstr & 0xFFFF; | |
55 | tinstr >>= 16; | |
56 | } | |
57 | else | |
58 | { | |
59 | next_instr = tinstr >> 16; | |
60 | tinstr &= 0xFFFF; | |
61 | } | |
dfcd3bfb JM |
62 | |
63 | #if 1 /* debugging to catch non updates */ | |
c906108c SS |
64 | *ainstr = 0xDEADC0DE; |
65 | #endif | |
66 | ||
67 | switch ((tinstr & 0xF800) >> 11) | |
68 | { | |
dfcd3bfb JM |
69 | case 0: /* LSL */ |
70 | case 1: /* LSR */ | |
71 | case 2: /* ASR */ | |
c906108c | 72 | /* Format 1 */ |
dfcd3bfb JM |
73 | *ainstr = 0xE1B00000 /* base opcode */ |
74 | | ((tinstr & 0x1800) >> (11 - 5)) /* shift type */ | |
75 | | ((tinstr & 0x07C0) << (7 - 6)) /* imm5 */ | |
76 | | ((tinstr & 0x0038) >> 3) /* Rs */ | |
77 | | ((tinstr & 0x0007) << 12); /* Rd */ | |
c906108c | 78 | break; |
dfcd3bfb | 79 | case 3: /* ADD/SUB */ |
c906108c SS |
80 | /* Format 2 */ |
81 | { | |
dfcd3bfb JM |
82 | ARMword subset[4] = { |
83 | 0xE0900000, /* ADDS Rd,Rs,Rn */ | |
84 | 0xE0500000, /* SUBS Rd,Rs,Rn */ | |
85 | 0xE2900000, /* ADDS Rd,Rs,#imm3 */ | |
86 | 0xE2500000 /* SUBS Rd,Rs,#imm3 */ | |
87 | }; | |
88 | /* It is quicker indexing into a table, than performing switch | |
89 | or conditionals: */ | |
90 | *ainstr = subset[(tinstr & 0x0600) >> 9] /* base opcode */ | |
91 | | ((tinstr & 0x01C0) >> 6) /* Rn or imm3 */ | |
92 | | ((tinstr & 0x0038) << (16 - 3)) /* Rs */ | |
93 | | ((tinstr & 0x0007) << (12 - 0)); /* Rd */ | |
c906108c SS |
94 | } |
95 | break; | |
dfcd3bfb JM |
96 | case 4: /* MOV */ |
97 | case 5: /* CMP */ | |
98 | case 6: /* ADD */ | |
99 | case 7: /* SUB */ | |
c906108c SS |
100 | /* Format 3 */ |
101 | { | |
dfcd3bfb JM |
102 | ARMword subset[4] = { |
103 | 0xE3B00000, /* MOVS Rd,#imm8 */ | |
104 | 0xE3500000, /* CMP Rd,#imm8 */ | |
105 | 0xE2900000, /* ADDS Rd,Rd,#imm8 */ | |
106 | 0xE2500000, /* SUBS Rd,Rd,#imm8 */ | |
107 | }; | |
108 | *ainstr = subset[(tinstr & 0x1800) >> 11] /* base opcode */ | |
109 | | ((tinstr & 0x00FF) >> 0) /* imm8 */ | |
110 | | ((tinstr & 0x0700) << (16 - 8)) /* Rn */ | |
111 | | ((tinstr & 0x0700) << (12 - 8)); /* Rd */ | |
c906108c | 112 | } |
dfcd3bfb JM |
113 | break; |
114 | case 8: /* Arithmetic and high register transfers */ | |
c906108c SS |
115 | /* TODO: Since the subsets for both Format 4 and Format 5 |
116 | instructions are made up of different ARM encodings, we could | |
117 | save the following conditional, and just have one large | |
118 | subset. */ | |
119 | if ((tinstr & (1 << 10)) == 0) | |
dfcd3bfb JM |
120 | { |
121 | /* Format 4 */ | |
122 | struct | |
123 | { | |
124 | ARMword opcode; | |
125 | enum | |
126 | { t_norm, t_shift, t_neg, t_mul } | |
127 | otype; | |
128 | } | |
129 | subset[16] = | |
130 | { | |
131 | { 0xE0100000, t_norm}, /* ANDS Rd,Rd,Rs */ | |
132 | { 0xE0300000, t_norm}, /* EORS Rd,Rd,Rs */ | |
133 | { 0xE1B00010, t_shift}, /* MOVS Rd,Rd,LSL Rs */ | |
134 | { 0xE1B00030, t_shift}, /* MOVS Rd,Rd,LSR Rs */ | |
135 | { 0xE1B00050, t_shift}, /* MOVS Rd,Rd,ASR Rs */ | |
136 | { 0xE0B00000, t_norm}, /* ADCS Rd,Rd,Rs */ | |
137 | { 0xE0D00000, t_norm}, /* SBCS Rd,Rd,Rs */ | |
138 | { 0xE1B00070, t_shift}, /* MOVS Rd,Rd,ROR Rs */ | |
139 | { 0xE1100000, t_norm}, /* TST Rd,Rs */ | |
140 | { 0xE2700000, t_neg}, /* RSBS Rd,Rs,#0 */ | |
141 | { 0xE1500000, t_norm}, /* CMP Rd,Rs */ | |
142 | { 0xE1700000, t_norm}, /* CMN Rd,Rs */ | |
143 | { 0xE1900000, t_norm}, /* ORRS Rd,Rd,Rs */ | |
144 | { 0xE0100090, t_mul} , /* MULS Rd,Rd,Rs */ | |
145 | { 0xE1D00000, t_norm}, /* BICS Rd,Rd,Rs */ | |
146 | { 0xE1F00000, t_norm} /* MVNS Rd,Rs */ | |
147 | }; | |
148 | *ainstr = subset[(tinstr & 0x03C0) >> 6].opcode; /* base */ | |
149 | switch (subset[(tinstr & 0x03C0) >> 6].otype) | |
150 | { | |
151 | case t_norm: | |
152 | *ainstr |= ((tinstr & 0x0007) << 16) /* Rn */ | |
153 | | ((tinstr & 0x0007) << 12) /* Rd */ | |
154 | | ((tinstr & 0x0038) >> 3); /* Rs */ | |
155 | break; | |
156 | case t_shift: | |
157 | *ainstr |= ((tinstr & 0x0007) << 12) /* Rd */ | |
158 | | ((tinstr & 0x0007) >> 0) /* Rm */ | |
159 | | ((tinstr & 0x0038) << (8 - 3)); /* Rs */ | |
160 | break; | |
161 | case t_neg: | |
162 | *ainstr |= ((tinstr & 0x0007) << 12) /* Rd */ | |
163 | | ((tinstr & 0x0038) << (16 - 3)); /* Rn */ | |
164 | break; | |
165 | case t_mul: | |
166 | *ainstr |= ((tinstr & 0x0007) << 16) /* Rd */ | |
167 | | ((tinstr & 0x0007) << 8) /* Rs */ | |
168 | | ((tinstr & 0x0038) >> 3); /* Rm */ | |
169 | break; | |
170 | } | |
171 | } | |
c906108c | 172 | else |
dfcd3bfb JM |
173 | { |
174 | /* Format 5 */ | |
175 | ARMword Rd = ((tinstr & 0x0007) >> 0); | |
176 | ARMword Rs = ((tinstr & 0x0038) >> 3); | |
177 | if (tinstr & (1 << 7)) | |
178 | Rd += 8; | |
179 | if (tinstr & (1 << 6)) | |
180 | Rs += 8; | |
181 | switch ((tinstr & 0x03C0) >> 6) | |
182 | { | |
183 | case 0x1: /* ADD Rd,Rd,Hs */ | |
184 | case 0x2: /* ADD Hd,Hd,Rs */ | |
185 | case 0x3: /* ADD Hd,Hd,Hs */ | |
186 | *ainstr = 0xE0800000 /* base */ | |
187 | | (Rd << 16) /* Rn */ | |
188 | | (Rd << 12) /* Rd */ | |
189 | | (Rs << 0); /* Rm */ | |
190 | break; | |
191 | case 0x5: /* CMP Rd,Hs */ | |
192 | case 0x6: /* CMP Hd,Rs */ | |
193 | case 0x7: /* CMP Hd,Hs */ | |
194 | *ainstr = 0xE1500000 /* base */ | |
195 | | (Rd << 16) /* Rn */ | |
196 | | (Rd << 12) /* Rd */ | |
197 | | (Rs << 0); /* Rm */ | |
198 | break; | |
199 | case 0x9: /* MOV Rd,Hs */ | |
200 | case 0xA: /* MOV Hd,Rs */ | |
201 | case 0xB: /* MOV Hd,Hs */ | |
202 | *ainstr = 0xE1A00000 /* base */ | |
203 | | (Rd << 16) /* Rn */ | |
204 | | (Rd << 12) /* Rd */ | |
205 | | (Rs << 0); /* Rm */ | |
206 | break; | |
207 | case 0xC: /* BX Rs */ | |
208 | case 0xD: /* BX Hs */ | |
209 | *ainstr = 0xE12FFF10 /* base */ | |
210 | | ((tinstr & 0x0078) >> 3); /* Rd */ | |
211 | break; | |
212 | case 0x0: /* UNDEFINED */ | |
213 | case 0x4: /* UNDEFINED */ | |
214 | case 0x8: /* UNDEFINED */ | |
215 | case 0xE: /* UNDEFINED */ | |
216 | case 0xF: /* UNDEFINED */ | |
217 | valid = t_undefined; | |
218 | break; | |
219 | } | |
220 | } | |
c906108c | 221 | break; |
dfcd3bfb | 222 | case 9: /* LDR Rd,[PC,#imm8] */ |
c906108c | 223 | /* Format 6 */ |
dfcd3bfb JM |
224 | *ainstr = 0xE59F0000 /* base */ |
225 | | ((tinstr & 0x0700) << (12 - 8)) /* Rd */ | |
226 | | ((tinstr & 0x00FF) << (2 - 0)); /* off8 */ | |
c906108c SS |
227 | break; |
228 | case 10: | |
229 | case 11: | |
230 | /* TODO: Format 7 and Format 8 perform the same ARM encoding, so | |
231 | the following could be merged into a single subset, saving on | |
232 | the following boolean: */ | |
233 | if ((tinstr & (1 << 9)) == 0) | |
dfcd3bfb JM |
234 | { |
235 | /* Format 7 */ | |
236 | ARMword subset[4] = { | |
237 | 0xE7800000, /* STR Rd,[Rb,Ro] */ | |
238 | 0xE7C00000, /* STRB Rd,[Rb,Ro] */ | |
239 | 0xE7900000, /* LDR Rd,[Rb,Ro] */ | |
240 | 0xE7D00000 /* LDRB Rd,[Rb,Ro] */ | |
241 | }; | |
242 | *ainstr = subset[(tinstr & 0x0C00) >> 10] /* base */ | |
243 | | ((tinstr & 0x0007) << (12 - 0)) /* Rd */ | |
244 | | ((tinstr & 0x0038) << (16 - 3)) /* Rb */ | |
245 | | ((tinstr & 0x01C0) >> 6); /* Ro */ | |
246 | } | |
c906108c | 247 | else |
dfcd3bfb JM |
248 | { |
249 | /* Format 8 */ | |
250 | ARMword subset[4] = { | |
251 | 0xE18000B0, /* STRH Rd,[Rb,Ro] */ | |
252 | 0xE19000D0, /* LDRSB Rd,[Rb,Ro] */ | |
253 | 0xE19000B0, /* LDRH Rd,[Rb,Ro] */ | |
254 | 0xE19000F0 /* LDRSH Rd,[Rb,Ro] */ | |
255 | }; | |
256 | *ainstr = subset[(tinstr & 0x0C00) >> 10] /* base */ | |
257 | | ((tinstr & 0x0007) << (12 - 0)) /* Rd */ | |
258 | | ((tinstr & 0x0038) << (16 - 3)) /* Rb */ | |
259 | | ((tinstr & 0x01C0) >> 6); /* Ro */ | |
260 | } | |
c906108c | 261 | break; |
dfcd3bfb JM |
262 | case 12: /* STR Rd,[Rb,#imm5] */ |
263 | case 13: /* LDR Rd,[Rb,#imm5] */ | |
264 | case 14: /* STRB Rd,[Rb,#imm5] */ | |
265 | case 15: /* LDRB Rd,[Rb,#imm5] */ | |
c906108c SS |
266 | /* Format 9 */ |
267 | { | |
dfcd3bfb JM |
268 | ARMword subset[4] = { |
269 | 0xE5800000, /* STR Rd,[Rb,#imm5] */ | |
270 | 0xE5900000, /* LDR Rd,[Rb,#imm5] */ | |
271 | 0xE5C00000, /* STRB Rd,[Rb,#imm5] */ | |
272 | 0xE5D00000 /* LDRB Rd,[Rb,#imm5] */ | |
273 | }; | |
274 | /* The offset range defends on whether we are transferring a | |
275 | byte or word value: */ | |
276 | *ainstr = subset[(tinstr & 0x1800) >> 11] /* base */ | |
277 | | ((tinstr & 0x0007) << (12 - 0)) /* Rd */ | |
278 | | ((tinstr & 0x0038) << (16 - 3)) /* Rb */ | |
279 | | ((tinstr & 0x07C0) >> (6 - ((tinstr & (1 << 12)) ? 0 : 2))); /* off5 */ | |
c906108c SS |
280 | } |
281 | break; | |
dfcd3bfb JM |
282 | case 16: /* STRH Rd,[Rb,#imm5] */ |
283 | case 17: /* LDRH Rd,[Rb,#imm5] */ | |
c906108c | 284 | /* Format 10 */ |
dfcd3bfb JM |
285 | *ainstr = ((tinstr & (1 << 11)) /* base */ |
286 | ? 0xE1D000B0 /* LDRH */ | |
287 | : 0xE1C000B0) /* STRH */ | |
288 | | ((tinstr & 0x0007) << (12 - 0)) /* Rd */ | |
289 | | ((tinstr & 0x0038) << (16 - 3)) /* Rb */ | |
290 | | ((tinstr & 0x01C0) >> (6 - 1)) /* off5, low nibble */ | |
291 | | ((tinstr & 0x0600) >> (9 - 8)); /* off5, high nibble */ | |
c906108c | 292 | break; |
dfcd3bfb JM |
293 | case 18: /* STR Rd,[SP,#imm8] */ |
294 | case 19: /* LDR Rd,[SP,#imm8] */ | |
c906108c | 295 | /* Format 11 */ |
dfcd3bfb JM |
296 | *ainstr = ((tinstr & (1 << 11)) /* base */ |
297 | ? 0xE59D0000 /* LDR */ | |
298 | : 0xE58D0000) /* STR */ | |
299 | | ((tinstr & 0x0700) << (12 - 8)) /* Rd */ | |
300 | | ((tinstr & 0x00FF) << 2); /* off8 */ | |
c906108c | 301 | break; |
dfcd3bfb JM |
302 | case 20: /* ADD Rd,PC,#imm8 */ |
303 | case 21: /* ADD Rd,SP,#imm8 */ | |
c906108c SS |
304 | /* Format 12 */ |
305 | if ((tinstr & (1 << 11)) == 0) | |
dfcd3bfb JM |
306 | { |
307 | /* NOTE: The PC value used here should by word aligned */ | |
c906108c SS |
308 | /* We encode shift-left-by-2 in the rotate immediate field, |
309 | so no shift of off8 is needed. */ | |
dfcd3bfb JM |
310 | *ainstr = 0xE28F0F00 /* base */ |
311 | | ((tinstr & 0x0700) << (12 - 8)) /* Rd */ | |
312 | | (tinstr & 0x00FF); /* off8 */ | |
313 | } | |
c906108c | 314 | else |
dfcd3bfb | 315 | { |
c906108c SS |
316 | /* We encode shift-left-by-2 in the rotate immediate field, |
317 | so no shift of off8 is needed. */ | |
dfcd3bfb JM |
318 | *ainstr = 0xE28D0F00 /* base */ |
319 | | ((tinstr & 0x0700) << (12 - 8)) /* Rd */ | |
320 | | (tinstr & 0x00FF); /* off8 */ | |
321 | } | |
c906108c SS |
322 | break; |
323 | case 22: | |
324 | case 23: | |
325 | if ((tinstr & 0x0F00) == 0x0000) | |
dfcd3bfb JM |
326 | { |
327 | /* Format 13 */ | |
328 | /* NOTE: The instruction contains a shift left of 2 | |
329 | equivalent (implemented as ROR #30): */ | |
330 | *ainstr = ((tinstr & (1 << 7)) /* base */ | |
331 | ? 0xE24DDF00 /* SUB */ | |
332 | : 0xE28DDF00) /* ADD */ | |
333 | | (tinstr & 0x007F); /* off7 */ | |
334 | } | |
5c44784c | 335 | else if ((tinstr & 0x0F00) == 0x0e00) |
dfcd3bfb | 336 | *ainstr = 0xEF000000 | SWI_Breakpoint; |
c906108c | 337 | else |
dfcd3bfb JM |
338 | { |
339 | /* Format 14 */ | |
340 | ARMword subset[4] = { | |
341 | 0xE92D0000, /* STMDB sp!,{rlist} */ | |
342 | 0xE92D4000, /* STMDB sp!,{rlist,lr} */ | |
343 | 0xE8BD0000, /* LDMIA sp!,{rlist} */ | |
344 | 0xE8BD8000 /* LDMIA sp!,{rlist,pc} */ | |
345 | }; | |
346 | *ainstr = subset[((tinstr & (1 << 11)) >> 10) | |
347 | | ((tinstr & (1 << 8)) >> 8)] /* base */ | |
348 | | (tinstr & 0x00FF); /* mask8 */ | |
349 | } | |
c906108c | 350 | break; |
dfcd3bfb JM |
351 | case 24: /* STMIA */ |
352 | case 25: /* LDMIA */ | |
c906108c | 353 | /* Format 15 */ |
dfcd3bfb JM |
354 | *ainstr = ((tinstr & (1 << 11)) /* base */ |
355 | ? 0xE8B00000 /* LDMIA */ | |
356 | : 0xE8A00000) /* STMIA */ | |
357 | | ((tinstr & 0x0700) << (16 - 8)) /* Rb */ | |
358 | | (tinstr & 0x00FF); /* mask8 */ | |
c906108c | 359 | break; |
dfcd3bfb JM |
360 | case 26: /* Bcc */ |
361 | case 27: /* Bcc/SWI */ | |
c906108c | 362 | if ((tinstr & 0x0F00) == 0x0F00) |
dfcd3bfb JM |
363 | { |
364 | /* Format 17 : SWI */ | |
365 | *ainstr = 0xEF000000; | |
c906108c SS |
366 | /* Breakpoint must be handled specially. */ |
367 | if ((tinstr & 0x00FF) == 0x18) | |
368 | *ainstr |= ((tinstr & 0x00FF) << 16); | |
7a292a7a SS |
369 | /* New breakpoint value. See gdb/arm-tdep.c */ |
370 | else if ((tinstr & 0x00FF) == 0xFE) | |
dfcd3bfb | 371 | *ainstr |= SWI_Breakpoint; |
c906108c SS |
372 | else |
373 | *ainstr |= (tinstr & 0x00FF); | |
dfcd3bfb | 374 | } |
c906108c | 375 | else if ((tinstr & 0x0F00) != 0x0E00) |
dfcd3bfb JM |
376 | { |
377 | /* Format 16 */ | |
378 | int doit = FALSE; | |
379 | /* TODO: Since we are doing a switch here, we could just add | |
380 | the SWI and undefined instruction checks into this | |
381 | switch to same on a couple of conditionals: */ | |
382 | switch ((tinstr & 0x0F00) >> 8) | |
383 | { | |
384 | case EQ: | |
385 | doit = ZFLAG; | |
386 | break; | |
387 | case NE: | |
388 | doit = !ZFLAG; | |
389 | break; | |
390 | case VS: | |
391 | doit = VFLAG; | |
392 | break; | |
393 | case VC: | |
394 | doit = !VFLAG; | |
395 | break; | |
396 | case MI: | |
397 | doit = NFLAG; | |
398 | break; | |
399 | case PL: | |
400 | doit = !NFLAG; | |
401 | break; | |
402 | case CS: | |
403 | doit = CFLAG; | |
404 | break; | |
405 | case CC: | |
406 | doit = !CFLAG; | |
407 | break; | |
408 | case HI: | |
409 | doit = (CFLAG && !ZFLAG); | |
410 | break; | |
411 | case LS: | |
412 | doit = (!CFLAG || ZFLAG); | |
413 | break; | |
414 | case GE: | |
415 | doit = ((!NFLAG && !VFLAG) || (NFLAG && VFLAG)); | |
416 | break; | |
417 | case LT: | |
418 | doit = ((NFLAG && !VFLAG) || (!NFLAG && VFLAG)); | |
419 | break; | |
420 | case GT: | |
421 | doit = ((!NFLAG && !VFLAG && !ZFLAG) | |
422 | || (NFLAG && VFLAG && !ZFLAG)); | |
423 | break; | |
424 | case LE: | |
425 | doit = ((NFLAG && !VFLAG) || (!NFLAG && VFLAG)) || ZFLAG; | |
426 | break; | |
427 | } | |
428 | if (doit) | |
429 | { | |
430 | state->Reg[15] = (pc + 4 | |
431 | + (((tinstr & 0x7F) << 1) | |
432 | | ((tinstr & (1 << 7)) ? 0xFFFFFF00 : 0))); | |
433 | FLUSHPIPE; | |
434 | } | |
435 | valid = t_branch; | |
436 | } | |
437 | else /* UNDEFINED : cc=1110(AL) uses different format */ | |
438 | valid = t_undefined; | |
c906108c | 439 | break; |
dfcd3bfb | 440 | case 28: /* B */ |
c906108c | 441 | /* Format 18 */ |
dfcd3bfb JM |
442 | state->Reg[15] = (pc + 4 |
443 | + (((tinstr & 0x3FF) << 1) | |
444 | | ((tinstr & (1 << 10)) ? 0xFFFFF800 : 0))); | |
c906108c SS |
445 | FLUSHPIPE; |
446 | valid = t_branch; | |
447 | break; | |
dfcd3bfb | 448 | case 29: /* UNDEFINED */ |
c906108c SS |
449 | valid = t_undefined; |
450 | break; | |
dfcd3bfb | 451 | case 30: /* BL instruction 1 */ |
c906108c SS |
452 | /* Format 19 */ |
453 | /* There is no single ARM instruction equivalent for this Thumb | |
454 | instruction. To keep the simulation simple (from the user | |
455 | perspective) we check if the following instruction is the | |
456 | second half of this BL, and if it is we simulate it | |
dfcd3bfb | 457 | immediately. */ |
c906108c | 458 | state->Reg[14] = state->Reg[15] \ |
dfcd3bfb JM |
459 | +(((tinstr & 0x07FF) << 12) \ |
460 | |((tinstr & (1 << 10)) ? 0xFF800000 : 0)); | |
461 | valid = t_branch; /* in-case we don't have the 2nd half */ | |
462 | tinstr = next_instr; /* move the instruction down */ | |
c906108c | 463 | if (((tinstr & 0xF800) >> 11) != 31) |
dfcd3bfb | 464 | break; /* exit, since not correct instruction */ |
c906108c | 465 | /* else we fall through to process the second half of the BL */ |
dfcd3bfb JM |
466 | pc += 2; /* point the pc at the 2nd half */ |
467 | case 31: /* BL instruction 2 */ | |
c906108c SS |
468 | /* Format 19 */ |
469 | /* There is no single ARM instruction equivalent for this | |
470 | instruction. Also, it should only ever be matched with the | |
471 | fmt19 "BL instruction 1" instruction. However, we do allow | |
472 | the simulation of it on its own, with undefined results if | |
dfcd3bfb | 473 | r14 is not suitably initialised. */ |
c906108c | 474 | { |
dfcd3bfb JM |
475 | ARMword tmp = (pc + 2); |
476 | state->Reg[15] = (state->Reg[14] + ((tinstr & 0x07FF) << 1)); | |
477 | state->Reg[14] = (tmp | 1); | |
478 | valid = t_branch; | |
479 | FLUSHPIPE; | |
c906108c SS |
480 | } |
481 | break; | |
482 | } | |
483 | ||
484 | return valid; | |
485 | } |