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1 | /// -*- mode: asm; asm-comment-char: ?/ -*- |
2 | /// | |
3 | /// AESNI-based implementation of Rijndael | |
4 | /// | |
5 | /// (c) 2015 Straylight/Edgeware | |
6 | /// | |
7 | ||
8 | ///----- Licensing notice --------------------------------------------------- | |
9 | /// | |
10 | /// This file is part of Catacomb. | |
11 | /// | |
12 | /// Catacomb is free software; you can redistribute it and/or modify | |
13 | /// it under the terms of the GNU Library General Public License as | |
14 | /// published by the Free Software Foundation; either version 2 of the | |
15 | /// License, or (at your option) any later version. | |
16 | /// | |
17 | /// Catacomb is distributed in the hope that it will be useful, | |
18 | /// but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | /// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | /// GNU Library General Public License for more details. | |
21 | /// | |
22 | /// You should have received a copy of the GNU Library General Public | |
23 | /// License along with Catacomb; if not, write to the Free | |
24 | /// Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, | |
25 | /// MA 02111-1307, USA. | |
26 | ||
27 | ///-------------------------------------------------------------------------- | |
28 | /// External definitions. | |
29 | ||
30 | #include "config.h" | |
31 | #include "asm-common.h" | |
32 | ||
81bc2bb8 MW |
33 | .extern F(abort) |
34 | .extern F(rijndael_rcon) | |
1a0c09c4 MW |
35 | |
36 | ///-------------------------------------------------------------------------- | |
37 | /// Main code. | |
38 | ||
39 | .arch .aes | |
bc9ac7eb | 40 | .text |
1a0c09c4 MW |
41 | |
42 | /// The AESNI instructions implement a little-endian version of AES, but | |
43 | /// Catacomb's internal interface presents as big-endian so as to work better | |
44 | /// with things like GCM. We therefore maintain the round keys in | |
45 | /// little-endian form, and have to end-swap blocks in and out. | |
46 | /// | |
47 | /// For added amusement, the AESNI instructions don't implement the | |
48 | /// larger-block versions of Rijndael, so we have to end-swap the keys if | |
49 | /// we're preparing for one of those. | |
50 | ||
51 | // Useful constants. | |
52 | .equ maxrounds, 16 // maximum number of rounds | |
53 | .equ maxblksz, 32 // maximum block size, in bytes | |
54 | .equ kbufsz, maxblksz*(maxrounds + 1) // size of a key-schedule buffer | |
55 | ||
56 | // Context structure. | |
57 | .equ nr, 0 // number of rounds | |
58 | .equ w, nr + 4 // encryption key words | |
59 | .equ wi, w + kbufsz // decryption key words | |
60 | ||
61 | ///-------------------------------------------------------------------------- | |
62 | /// Key setup. | |
63 | ||
0f23f75f | 64 | FUNC(rijndael_setup_x86ish_aesni) |
1a0c09c4 | 65 | |
43ea7558 MW |
66 | #define SI WHOLE(si) |
67 | #define DI WHOLE(di) | |
68 | ||
0f23f75f MW |
69 | #if CPUFAM_X86 |
70 | // Arguments are on the stack. We'll need to stack the caller's | |
71 | // register veriables, but we'll manage. | |
1a0c09c4 | 72 | |
0f23f75f MW |
73 | # define CTX ebp // context pointer |
74 | # define BLKSZ [esp + 24] // block size | |
75 | ||
0f23f75f | 76 | # define KSZ ebx // key size |
0f23f75f MW |
77 | # define NKW edx // total number of key words |
78 | # define NKW_NEEDS_REFRESH 1 // ... needs recalculating | |
79 | # define RCON ecx // round constants table | |
80 | # define LIM edx // limit pointer | |
16021451 | 81 | # define CYIX edi // index in shift-register cycle |
0f23f75f MW |
82 | |
83 | # define NR ecx // number of rounds | |
84 | # define LRK eax // distance to last key | |
0f23f75f | 85 | # define BLKOFF edx // block size in bytes |
0f23f75f MW |
86 | |
87 | // Stack the caller's registers. | |
0923a413 MW |
88 | pushreg ebp |
89 | pushreg ebx | |
90 | pushreg esi | |
91 | pushreg edi | |
1a0c09c4 | 92 | |
0f23f75f MW |
93 | // Set up our own variables. |
94 | mov CTX, [esp + 20] // context base pointer | |
95 | mov SI, [esp + 28] // key material | |
96 | mov KSZ, [esp + 32] // key size, in words | |
97 | #endif | |
98 | ||
99 | #if CPUFAM_AMD64 && ABI_SYSV | |
100 | // Arguments are in registers. We have plenty, but, to be honest, | |
101 | // the initial register allocation is a bit annoying. | |
102 | ||
103 | # define CTX r8 // context pointer | |
104 | # define BLKSZ r9d // block size | |
105 | ||
0f23f75f | 106 | # define KSZ edx // key size |
0f23f75f MW |
107 | # define NKW r10d // total number of key words |
108 | # define RCON rdi // round constants table | |
43ea7558 | 109 | # define LIM rcx // limit pointer |
16021451 | 110 | # define CYIX r11d // index in shift-register cycle |
0f23f75f MW |
111 | |
112 | # define NR ecx // number of rounds | |
113 | # define LRK eax // distance to last key | |
0f23f75f | 114 | # define BLKOFF r9d // block size in bytes |
0f23f75f MW |
115 | |
116 | // Move arguments to more useful places. | |
117 | mov CTX, rdi // context base pointer | |
118 | mov BLKSZ, esi // block size in words | |
119 | mov SI, rdx // key material | |
120 | mov KSZ, ecx // key size, in words | |
121 | #endif | |
122 | ||
123 | #if CPUFAM_AMD64 && ABI_WIN | |
124 | // Arguments are in different registers, and they're a little tight. | |
125 | ||
126 | # define CTX r8 // context pointer | |
127 | # define BLKSZ edx // block size | |
128 | ||
0f23f75f | 129 | # define KSZ r9d // key size |
0f23f75f MW |
130 | # define NKW r10d // total number of key words |
131 | # define RCON rdi // round constants table | |
43ea7558 | 132 | # define LIM rcx // limit pointer |
16021451 | 133 | # define CYIX r11d // index in shift-register cycle |
0f23f75f MW |
134 | |
135 | # define NR ecx // number of rounds | |
136 | # define LRK eax // distance to last key | |
0f23f75f | 137 | # define BLKOFF edx // block size in bytes |
0f23f75f MW |
138 | |
139 | // We'll need the index registers, which belong to the caller in this | |
140 | // ABI. | |
0923a413 MW |
141 | pushreg rsi |
142 | pushreg rdi | |
0f23f75f MW |
143 | |
144 | // Move arguments to more useful places. | |
43ea7558 | 145 | mov rsi, r8 // key material |
0f23f75f MW |
146 | mov CTX, rcx // context base pointer |
147 | #endif | |
148 | ||
0923a413 MW |
149 | endprologue |
150 | ||
1a0c09c4 MW |
151 | // The initial round key material is taken directly from the input |
152 | // key, so copy it over. | |
0f23f75f MW |
153 | #if CPUFAM_AMD64 && ABI_SYSV |
154 | // We've been lucky. We already have a copy of the context pointer | |
155 | // in rdi, and the key size in ecx. | |
43ea7558 | 156 | add rdi, w |
0f23f75f MW |
157 | #else |
158 | lea DI, [CTX + w] | |
159 | mov ecx, KSZ | |
160 | #endif | |
1a0c09c4 MW |
161 | rep movsd |
162 | ||
163 | // Find out other useful things. | |
0f23f75f MW |
164 | mov NKW, [CTX + nr] // number of rounds |
165 | add NKW, 1 | |
166 | imul NKW, BLKSZ // total key size in words | |
167 | #if !NKW_NEEDS_REFRESH | |
168 | // If we can't keep NKW for later, then we use the same register for | |
169 | // it and LIM, so this move is unnecessary. | |
43ea7558 | 170 | mov DWORD(LIM), NKW |
0f23f75f | 171 | #endif |
43ea7558 | 172 | sub DWORD(LIM), KSZ // offset by the key size |
1a0c09c4 MW |
173 | |
174 | // Find the round constants. | |
43ea7558 MW |
175 | ldgot WHOLE(c) |
176 | leaext RCON, F(rijndael_rcon), WHOLE(c) | |
1a0c09c4 MW |
177 | |
178 | // Prepare for the main loop. | |
0f23f75f | 179 | lea SI, [CTX + w] |
43ea7558 | 180 | mov eax, [SI + 4*WHOLE(KSZ) - 4] // most recent key word |
0f23f75f | 181 | lea LIM, [SI + 4*LIM] // limit, offset by one key expansion |
16021451 | 182 | xor CYIX, CYIX // start of new cycle |
1a0c09c4 MW |
183 | |
184 | // Main key expansion loop. The first word of each key-length chunk | |
185 | // needs special treatment. | |
186 | // | |
187 | // This is rather tedious because the Intel `AESKEYGENASSIST' | |
188 | // instruction is very strangely shaped. Firstly, it wants to | |
189 | // operate on vast SSE registers, even though we're data-blocked from | |
190 | // doing more than operation at a time unless we're doing two key | |
191 | // schedules simultaneously -- and even then we can't do more than | |
192 | // two, because the instruction ignores two of its input words | |
193 | // entirely, and produces two different outputs for each of the other | |
194 | // two. And secondly it insists on taking the magic round constant | |
195 | // as an immediate, so it's kind of annoying if you're not | |
196 | // open-coding the whole thing. It's much easier to leave that as | |
197 | // zero and XOR in the round constant by hand. | |
16021451 MW |
198 | 0: cmp CYIX, 0 // first word of the cycle? |
199 | je 1f | |
200 | cmp CYIX, 4 // fourth word of the cycle? | |
201 | jne 2f | |
202 | cmp KSZ, 7 // and a large key? | |
203 | jb 2f | |
204 | ||
205 | // Fourth word of the cycle, and seven or eight words of key. Do a | |
206 | // byte substitution. | |
207 | movd xmm0, eax | |
a13b5730 | 208 | pshufd xmm0, xmm0, SHUF(2, 1, 0, 3) |
16021451 MW |
209 | aeskeygenassist xmm1, xmm0, 0 |
210 | movd eax, xmm1 | |
211 | jmp 2f | |
212 | ||
213 | // First word of the cycle. This is the complicated piece. | |
214 | 1: movd xmm0, eax | |
a13b5730 | 215 | pshufd xmm0, xmm0, SHUF(0, 3, 2, 1) |
1a0c09c4 | 216 | aeskeygenassist xmm1, xmm0, 0 |
a13b5730 | 217 | pshufd xmm1, xmm1, SHUF(2, 1, 0, 3) |
1a0c09c4 | 218 | movd eax, xmm1 |
0f23f75f MW |
219 | xor al, [RCON] |
220 | inc RCON | |
1a0c09c4 | 221 | |
16021451 MW |
222 | // Common tail. Mix in the corresponding word from the previous |
223 | // cycle and prepare for the next loop. | |
224 | 2: xor eax, [SI] | |
43ea7558 | 225 | mov [SI + 4*WHOLE(KSZ)], eax |
0f23f75f | 226 | add SI, 4 |
16021451 | 227 | inc CYIX |
0f23f75f | 228 | cmp SI, LIM |
89b34050 | 229 | jae 9f |
16021451 | 230 | cmp CYIX, KSZ |
89b34050 | 231 | jb 0b |
16021451 | 232 | xor CYIX, CYIX |
89b34050 | 233 | jmp 0b |
1a0c09c4 MW |
234 | |
235 | // Next job is to construct the decryption keys. The keys for the | |
236 | // first and last rounds don't need to be mangled, but the remaining | |
237 | // ones do -- and they all need to be reordered too. | |
238 | // | |
239 | // The plan of action, then, is to copy the final encryption round's | |
240 | // keys into place first, then to do each of the intermediate rounds | |
241 | // in reverse order, and finally do the first round. | |
242 | // | |
243 | // Do all of the heavy lifting with SSE registers. The order we're | |
244 | // doing this in means that it's OK if we read or write too much, and | |
245 | // there's easily enough buffer space for the over-enthusiastic reads | |
246 | // and writes because the context has space for 32-byte blocks, which | |
247 | // is our maximum and an exact fit for two SSE registers. | |
89b34050 | 248 | 9: mov NR, [CTX + nr] // number of rounds |
0f23f75f MW |
249 | #if NKW_NEEDS_REFRESH |
250 | mov BLKOFF, BLKSZ | |
251 | mov LRK, NR | |
252 | imul LRK, BLKOFF | |
253 | #else | |
254 | // If we retain NKW, then BLKSZ and BLKOFF are the same register | |
255 | // because we won't need the former again. | |
256 | mov LRK, NKW | |
257 | sub LRK, BLKSZ | |
258 | #endif | |
259 | lea DI, [CTX + wi] | |
43ea7558 | 260 | lea SI, [CTX + w + 4*WHOLE(LRK)] // last round's keys |
0f23f75f | 261 | shl BLKOFF, 2 // block size (in bytes now) |
1a0c09c4 MW |
262 | |
263 | // Copy the last encryption round's keys. | |
0f23f75f MW |
264 | movdqu xmm0, [SI] |
265 | movdqu [DI], xmm0 | |
266 | cmp BLKOFF, 16 | |
89b34050 | 267 | jbe 0f |
0f23f75f MW |
268 | movdqu xmm0, [SI + 16] |
269 | movdqu [DI + 16], xmm0 | |
1a0c09c4 MW |
270 | |
271 | // Update the loop variables and stop if we've finished. | |
43ea7558 MW |
272 | 0: add DI, WHOLE(BLKOFF) |
273 | sub SI, WHOLE(BLKOFF) | |
0f23f75f | 274 | sub NR, 1 |
89b34050 | 275 | jbe 9f |
1a0c09c4 MW |
276 | |
277 | // Do another middle round's keys... | |
0f23f75f | 278 | movdqu xmm0, [SI] |
1a0c09c4 | 279 | aesimc xmm0, xmm0 |
0f23f75f MW |
280 | movdqu [DI], xmm0 |
281 | cmp BLKOFF, 16 | |
89b34050 | 282 | jbe 0b |
0f23f75f | 283 | movdqu xmm0, [SI + 16] |
1a0c09c4 | 284 | aesimc xmm0, xmm0 |
0f23f75f | 285 | movdqu [DI + 16], xmm0 |
89b34050 | 286 | jmp 0b |
1a0c09c4 MW |
287 | |
288 | // Finally do the first encryption round. | |
89b34050 | 289 | 9: movdqu xmm0, [SI] |
0f23f75f MW |
290 | movdqu [DI], xmm0 |
291 | cmp BLKOFF, 16 | |
89b34050 | 292 | jbe 1f |
0f23f75f MW |
293 | movdqu xmm0, [SI + 16] |
294 | movdqu [DI + 16], xmm0 | |
1a0c09c4 MW |
295 | |
296 | // If the block size is not exactly four words then we must end-swap | |
297 | // everything. We can use fancy SSE toys for this. | |
89b34050 MW |
298 | 1: cmp BLKOFF, 16 |
299 | je 9f | |
1a0c09c4 MW |
300 | |
301 | // Find the byte-reordering table. | |
302 | ldgot ecx | |
8d6ca554 | 303 | movdqa xmm5, [INTADDR(endswap_tab, ecx)] |
1a0c09c4 | 304 | |
0f23f75f | 305 | #if NKW_NEEDS_REFRESH |
1a0c09c4 MW |
306 | // Calculate the number of subkey words again. (It's a good job |
307 | // we've got a fast multiplier.) | |
0f23f75f MW |
308 | mov NKW, [CTX + nr] |
309 | add NKW, 1 | |
310 | imul NKW, BLKSZ | |
311 | #endif | |
1a0c09c4 MW |
312 | |
313 | // End-swap the encryption keys. | |
0f23f75f | 314 | lea SI, [CTX + w] |
1a0c09c4 MW |
315 | call endswap_block |
316 | ||
317 | // And the decryption keys. | |
0f23f75f | 318 | lea SI, [CTX + wi] |
1a0c09c4 MW |
319 | call endswap_block |
320 | ||
89b34050 | 321 | 9: // All done. |
0f23f75f | 322 | #if CPUFAM_X86 |
0923a413 MW |
323 | popreg edi |
324 | popreg esi | |
325 | popreg ebx | |
326 | popreg ebp | |
0f23f75f MW |
327 | #endif |
328 | #if CPUFAM_AMD64 && ABI_WIN | |
0923a413 MW |
329 | popreg rdi |
330 | popreg rsi | |
0f23f75f | 331 | #endif |
1a0c09c4 MW |
332 | ret |
333 | ||
1a517bb3 MW |
334 | ENDFUNC |
335 | ||
336 | INTFUNC(endswap_block) | |
1a384903 | 337 | // End-swap NKW words starting at SI. The end-swapping table is |
8d6ca554 | 338 | // already loaded into XMM5; and it's OK to work in 16-byte chunks. |
0923a413 | 339 | endprologue |
1a517bb3 | 340 | |
1a384903 MW |
341 | mov ecx, NKW |
342 | 0: movdqu xmm1, [SI] | |
8d6ca554 | 343 | pshufb xmm1, xmm5 |
0f23f75f MW |
344 | movdqu [SI], xmm1 |
345 | add SI, 16 | |
1a0c09c4 | 346 | sub ecx, 4 |
1a384903 | 347 | ja 0b |
1a517bb3 | 348 | |
1a0c09c4 MW |
349 | ret |
350 | ||
1a517bb3 MW |
351 | ENDFUNC |
352 | ||
0f23f75f MW |
353 | #undef CTX |
354 | #undef BLKSZ | |
355 | #undef SI | |
356 | #undef DI | |
357 | #undef KSZ | |
0f23f75f | 358 | #undef RCON |
0f23f75f MW |
359 | #undef LIM |
360 | #undef NR | |
361 | #undef LRK | |
0f23f75f | 362 | #undef BLKOFF |
0f23f75f | 363 | |
1a0c09c4 MW |
364 | ///-------------------------------------------------------------------------- |
365 | /// Encrypting and decrypting blocks. | |
366 | ||
8a1aa284 MW |
367 | .macro encdec op, aes, koff |
368 | FUNC(rijndael_\op\()_x86ish_aesni) | |
1a0c09c4 | 369 | |
0f23f75f MW |
370 | #if CPUFAM_X86 |
371 | // Arguments come in on the stack, and need to be collected. We | |
372 | // don't have a shortage of registers. | |
373 | ||
c410f911 | 374 | # define K eax |
0f23f75f MW |
375 | # define SRC edx |
376 | # define DST edx | |
c410f911 | 377 | # define NR ecx |
0f23f75f MW |
378 | |
379 | mov K, [esp + 4] | |
380 | mov SRC, [esp + 8] | |
381 | #endif | |
382 | ||
383 | #if CPUFAM_AMD64 && ABI_SYSV | |
384 | // Arguments come in registers. All is good. | |
385 | ||
386 | # define K rdi | |
387 | # define SRC rsi | |
388 | # define DST rdx | |
389 | # define NR eax | |
390 | #endif | |
391 | ||
392 | #if CPUFAM_AMD64 && ABI_WIN | |
393 | // Arguments come in different registers. | |
394 | ||
395 | # define K rcx | |
396 | # define SRC rdx | |
397 | # define DST r8 | |
398 | # define NR eax | |
399 | #endif | |
400 | ||
0923a413 MW |
401 | endprologue |
402 | ||
28321c96 MW |
403 | // Find the magic endianness-swapping table. |
404 | ldgot ecx | |
405 | movdqa xmm5, [INTADDR(endswap_tab, ecx)] | |
406 | ||
0f23f75f MW |
407 | // Initial setup. |
408 | movdqu xmm0, [SRC] | |
8d6ca554 | 409 | pshufb xmm0, xmm5 |
0f23f75f MW |
410 | mov NR, [K + nr] |
411 | add K, \koff | |
1a0c09c4 MW |
412 | |
413 | // Initial whitening. | |
0f23f75f MW |
414 | movdqu xmm1, [K] |
415 | add K, 16 | |
1a0c09c4 | 416 | pxor xmm0, xmm1 |
1d63fee4 MW |
417 | #if CPUFAM_X86 |
418 | mov DST, [esp + 12] | |
419 | #endif | |
1a0c09c4 MW |
420 | |
421 | // Dispatch to the correct code. | |
0f23f75f | 422 | cmp NR, 10 |
e297526c | 423 | je 10f |
1a0c09c4 | 424 | jb bogus |
0f23f75f | 425 | cmp NR, 14 |
e297526c | 426 | je 14f |
1a0c09c4 | 427 | ja bogus |
0f23f75f | 428 | cmp NR, 12 |
e297526c MW |
429 | je 12f |
430 | jb 11f | |
431 | jmp 13f | |
1a0c09c4 MW |
432 | |
433 | .align 2 | |
434 | ||
435 | // 14 rounds... | |
0f23f75f MW |
436 | 14: movdqu xmm1, [K] |
437 | add K, 16 | |
e297526c | 438 | \aes xmm0, xmm1 |
1a0c09c4 MW |
439 | |
440 | // 13 rounds... | |
0f23f75f MW |
441 | 13: movdqu xmm1, [K] |
442 | add K, 16 | |
e297526c | 443 | \aes xmm0, xmm1 |
1a0c09c4 MW |
444 | |
445 | // 12 rounds... | |
0f23f75f MW |
446 | 12: movdqu xmm1, [K] |
447 | add K, 16 | |
e297526c | 448 | \aes xmm0, xmm1 |
1a0c09c4 MW |
449 | |
450 | // 11 rounds... | |
0f23f75f MW |
451 | 11: movdqu xmm1, [K] |
452 | add K, 16 | |
e297526c | 453 | \aes xmm0, xmm1 |
1a0c09c4 MW |
454 | |
455 | // 10 rounds... | |
0f23f75f | 456 | 10: movdqu xmm1, [K] |
e297526c | 457 | \aes xmm0, xmm1 |
1a0c09c4 MW |
458 | |
459 | // 9 rounds... | |
0f23f75f | 460 | movdqu xmm1, [K + 16] |
e297526c | 461 | \aes xmm0, xmm1 |
1a0c09c4 MW |
462 | |
463 | // 8 rounds... | |
0f23f75f | 464 | movdqu xmm1, [K + 32] |
e297526c | 465 | \aes xmm0, xmm1 |
1a0c09c4 MW |
466 | |
467 | // 7 rounds... | |
0f23f75f | 468 | movdqu xmm1, [K + 48] |
e297526c | 469 | \aes xmm0, xmm1 |
1a0c09c4 MW |
470 | |
471 | // 6 rounds... | |
0f23f75f | 472 | movdqu xmm1, [K + 64] |
e297526c | 473 | \aes xmm0, xmm1 |
1a0c09c4 MW |
474 | |
475 | // 5 rounds... | |
0f23f75f | 476 | movdqu xmm1, [K + 80] |
e297526c | 477 | \aes xmm0, xmm1 |
1a0c09c4 MW |
478 | |
479 | // 4 rounds... | |
0f23f75f | 480 | movdqu xmm1, [K + 96] |
e297526c | 481 | \aes xmm0, xmm1 |
1a0c09c4 MW |
482 | |
483 | // 3 rounds... | |
0f23f75f | 484 | movdqu xmm1, [K + 112] |
e297526c | 485 | \aes xmm0, xmm1 |
1a0c09c4 MW |
486 | |
487 | // 2 rounds... | |
0f23f75f | 488 | movdqu xmm1, [K + 128] |
e297526c | 489 | \aes xmm0, xmm1 |
1a0c09c4 MW |
490 | |
491 | // Final round... | |
0f23f75f | 492 | movdqu xmm1, [K + 144] |
e297526c | 493 | \aes\()last xmm0, xmm1 |
1a0c09c4 MW |
494 | |
495 | // Unpermute the ciphertext block and store it. | |
8d6ca554 | 496 | pshufb xmm0, xmm5 |
0f23f75f | 497 | movdqu [DST], xmm0 |
1a0c09c4 MW |
498 | |
499 | // And we're done. | |
500 | ret | |
501 | ||
0f23f75f MW |
502 | #undef K |
503 | #undef SRC | |
504 | #undef DST | |
505 | #undef NR | |
506 | ||
8a1aa284 MW |
507 | ENDFUNC |
508 | .endm | |
1a0c09c4 | 509 | |
e297526c MW |
510 | encdec eblk, aesenc, w |
511 | encdec dblk, aesdec, wi | |
1a0c09c4 MW |
512 | |
513 | ///-------------------------------------------------------------------------- | |
514 | /// Random utilities. | |
515 | ||
1a517bb3 | 516 | INTFUNC(bogus) |
1a0c09c4 MW |
517 | // Abort the process because of a programming error. Indirecting |
518 | // through this point serves several purposes: (a) by CALLing, rather | |
519 | // than branching to, `abort', we can save the return address, which | |
520 | // might at least provide a hint as to what went wrong; (b) we don't | |
521 | // have conditional CALLs (and they'd be big anyway); and (c) we can | |
522 | // write a HLT here as a backstop against `abort' being mad. | |
0923a413 | 523 | endprologue |
1a517bb3 MW |
524 | |
525 | callext F(abort) | |
1a0c09c4 MW |
526 | 0: hlt |
527 | jmp 0b | |
528 | ||
1a517bb3 MW |
529 | ENDFUNC |
530 | ||
1a0c09c4 MW |
531 | ///-------------------------------------------------------------------------- |
532 | /// Data tables. | |
533 | ||
645fcce0 MW |
534 | RODATA |
535 | ||
1a0c09c4 MW |
536 | .align 16 |
537 | endswap_tab: | |
538 | .byte 3, 2, 1, 0 | |
539 | .byte 7, 6, 5, 4 | |
540 | .byte 11, 10, 9, 8 | |
541 | .byte 15, 14, 13, 12 | |
542 | ||
543 | ///----- That's all, folks -------------------------------------------------- |