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5ee18b9c MW |
1 | /* |
2 | * QEMU model of the Milkymist programmable FPU. | |
3 | * | |
4 | * Copyright (c) 2010 Michael Walle <michael@walle.cc> | |
5 | * | |
6 | * This library is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU Lesser General Public | |
8 | * License as published by the Free Software Foundation; either | |
9 | * version 2 of the License, or (at your option) any later version. | |
10 | * | |
11 | * This library is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | * Lesser General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU Lesser General Public | |
17 | * License along with this library; if not, see <http://www.gnu.org/licenses/>. | |
18 | * | |
19 | * | |
20 | * Specification available at: | |
21 | * http://www.milkymist.org/socdoc/pfpu.pdf | |
22 | * | |
23 | */ | |
24 | ||
25 | #include "hw.h" | |
26 | #include "sysbus.h" | |
27 | #include "trace.h" | |
28 | #include "qemu-log.h" | |
29 | #include "qemu-error.h" | |
30 | #include <math.h> | |
31 | ||
32 | /* #define TRACE_EXEC */ | |
33 | ||
34 | #ifdef TRACE_EXEC | |
35 | # define D_EXEC(x) x | |
36 | #else | |
37 | # define D_EXEC(x) | |
38 | #endif | |
39 | ||
40 | enum { | |
41 | R_CTL = 0, | |
42 | R_MESHBASE, | |
43 | R_HMESHLAST, | |
44 | R_VMESHLAST, | |
45 | R_CODEPAGE, | |
46 | R_VERTICES, | |
47 | R_COLLISIONS, | |
48 | R_STRAYWRITES, | |
49 | R_LASTDMA, | |
50 | R_PC, | |
51 | R_DREGBASE, | |
52 | R_CODEBASE, | |
53 | R_MAX | |
54 | }; | |
55 | ||
56 | enum { | |
57 | CTL_START_BUSY = (1<<0), | |
58 | }; | |
59 | ||
60 | enum { | |
61 | OP_NOP = 0, | |
62 | OP_FADD, | |
63 | OP_FSUB, | |
64 | OP_FMUL, | |
65 | OP_FABS, | |
66 | OP_F2I, | |
67 | OP_I2F, | |
68 | OP_VECTOUT, | |
69 | OP_SIN, | |
70 | OP_COS, | |
71 | OP_ABOVE, | |
72 | OP_EQUAL, | |
73 | OP_COPY, | |
74 | OP_IF, | |
75 | OP_TSIGN, | |
76 | OP_QUAKE, | |
77 | }; | |
78 | ||
79 | enum { | |
80 | GPR_X = 0, | |
81 | GPR_Y = 1, | |
82 | GPR_FLAGS = 2, | |
83 | }; | |
84 | ||
85 | enum { | |
86 | LATENCY_FADD = 5, | |
87 | LATENCY_FSUB = 5, | |
88 | LATENCY_FMUL = 7, | |
89 | LATENCY_FABS = 2, | |
90 | LATENCY_F2I = 2, | |
91 | LATENCY_I2F = 3, | |
92 | LATENCY_VECTOUT = 0, | |
93 | LATENCY_SIN = 4, | |
94 | LATENCY_COS = 4, | |
95 | LATENCY_ABOVE = 2, | |
96 | LATENCY_EQUAL = 2, | |
97 | LATENCY_COPY = 2, | |
98 | LATENCY_IF = 2, | |
99 | LATENCY_TSIGN = 2, | |
100 | LATENCY_QUAKE = 2, | |
101 | MAX_LATENCY = 7 | |
102 | }; | |
103 | ||
104 | #define GPR_BEGIN 0x100 | |
105 | #define GPR_END 0x17f | |
106 | #define MICROCODE_BEGIN 0x200 | |
107 | #define MICROCODE_END 0x3ff | |
108 | #define MICROCODE_WORDS 2048 | |
109 | ||
110 | #define REINTERPRET_CAST(type, val) (*((type *)&(val))) | |
111 | ||
112 | #ifdef TRACE_EXEC | |
113 | static const char *opcode_to_str[] = { | |
114 | "NOP", "FADD", "FSUB", "FMUL", "FABS", "F2I", "I2F", "VECTOUT", | |
115 | "SIN", "COS", "ABOVE", "EQUAL", "COPY", "IF", "TSIGN", "QUAKE", | |
116 | }; | |
117 | #endif | |
118 | ||
119 | struct MilkymistPFPUState { | |
120 | SysBusDevice busdev; | |
121 | CharDriverState *chr; | |
122 | qemu_irq irq; | |
123 | ||
124 | uint32_t regs[R_MAX]; | |
125 | uint32_t gp_regs[128]; | |
126 | uint32_t microcode[MICROCODE_WORDS]; | |
127 | ||
128 | int output_queue_pos; | |
129 | uint32_t output_queue[MAX_LATENCY]; | |
130 | }; | |
131 | typedef struct MilkymistPFPUState MilkymistPFPUState; | |
132 | ||
133 | static inline target_phys_addr_t | |
134 | get_dma_address(uint32_t base, uint32_t x, uint32_t y) | |
135 | { | |
136 | return base + 8 * (128 * y + x); | |
137 | } | |
138 | ||
139 | static inline void | |
140 | output_queue_insert(MilkymistPFPUState *s, uint32_t val, int pos) | |
141 | { | |
142 | s->output_queue[(s->output_queue_pos + pos) % MAX_LATENCY] = val; | |
143 | } | |
144 | ||
145 | static inline uint32_t | |
146 | output_queue_remove(MilkymistPFPUState *s) | |
147 | { | |
148 | return s->output_queue[s->output_queue_pos]; | |
149 | } | |
150 | ||
151 | static inline void | |
152 | output_queue_advance(MilkymistPFPUState *s) | |
153 | { | |
154 | s->output_queue[s->output_queue_pos] = 0; | |
155 | s->output_queue_pos = (s->output_queue_pos + 1) % MAX_LATENCY; | |
156 | } | |
157 | ||
158 | static int pfpu_decode_insn(MilkymistPFPUState *s) | |
159 | { | |
160 | uint32_t pc = s->regs[R_PC]; | |
161 | uint32_t insn = s->microcode[pc]; | |
162 | uint32_t reg_a = (insn >> 18) & 0x7f; | |
163 | uint32_t reg_b = (insn >> 11) & 0x7f; | |
164 | uint32_t op = (insn >> 7) & 0xf; | |
165 | uint32_t reg_d = insn & 0x7f; | |
7f7454ec | 166 | uint32_t r = 0; |
5ee18b9c MW |
167 | int latency = 0; |
168 | ||
169 | switch (op) { | |
170 | case OP_NOP: | |
171 | break; | |
172 | case OP_FADD: | |
173 | { | |
174 | float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]); | |
175 | float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]); | |
176 | float t = a + b; | |
177 | r = REINTERPRET_CAST(uint32_t, t); | |
178 | latency = LATENCY_FADD; | |
179 | D_EXEC(qemu_log("ADD a=%f b=%f t=%f, r=%08x\n", a, b, t, r)); | |
180 | } break; | |
181 | case OP_FSUB: | |
182 | { | |
183 | float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]); | |
184 | float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]); | |
185 | float t = a - b; | |
186 | r = REINTERPRET_CAST(uint32_t, t); | |
187 | latency = LATENCY_FSUB; | |
188 | D_EXEC(qemu_log("SUB a=%f b=%f t=%f, r=%08x\n", a, b, t, r)); | |
189 | } break; | |
190 | case OP_FMUL: | |
191 | { | |
192 | float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]); | |
193 | float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]); | |
194 | float t = a * b; | |
195 | r = REINTERPRET_CAST(uint32_t, t); | |
196 | latency = LATENCY_FMUL; | |
197 | D_EXEC(qemu_log("MUL a=%f b=%f t=%f, r=%08x\n", a, b, t, r)); | |
198 | } break; | |
199 | case OP_FABS: | |
200 | { | |
201 | float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]); | |
202 | float t = fabsf(a); | |
203 | r = REINTERPRET_CAST(uint32_t, t); | |
204 | latency = LATENCY_FABS; | |
205 | D_EXEC(qemu_log("ABS a=%f t=%f, r=%08x\n", a, t, r)); | |
206 | } break; | |
207 | case OP_F2I: | |
208 | { | |
209 | float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]); | |
210 | int32_t t = a; | |
211 | r = REINTERPRET_CAST(uint32_t, t); | |
212 | latency = LATENCY_F2I; | |
213 | D_EXEC(qemu_log("F2I a=%f t=%d, r=%08x\n", a, t, r)); | |
214 | } break; | |
215 | case OP_I2F: | |
216 | { | |
217 | int32_t a = REINTERPRET_CAST(int32_t, s->gp_regs[reg_a]); | |
218 | float t = a; | |
219 | r = REINTERPRET_CAST(uint32_t, t); | |
220 | latency = LATENCY_I2F; | |
221 | D_EXEC(qemu_log("I2F a=%08x t=%f, r=%08x\n", a, t, r)); | |
222 | } break; | |
223 | case OP_VECTOUT: | |
224 | { | |
225 | uint32_t a = cpu_to_be32(s->gp_regs[reg_a]); | |
226 | uint32_t b = cpu_to_be32(s->gp_regs[reg_b]); | |
227 | target_phys_addr_t dma_ptr = | |
228 | get_dma_address(s->regs[R_MESHBASE], | |
229 | s->gp_regs[GPR_X], s->gp_regs[GPR_Y]); | |
230 | cpu_physical_memory_write(dma_ptr, (uint8_t *)&a, 4); | |
231 | cpu_physical_memory_write(dma_ptr + 4, (uint8_t *)&b, 4); | |
232 | s->regs[R_LASTDMA] = dma_ptr + 4; | |
233 | D_EXEC(qemu_log("VECTOUT a=%08x b=%08x dma=%08x\n", a, b, dma_ptr)); | |
234 | trace_milkymist_pfpu_vectout(a, b, dma_ptr); | |
235 | } break; | |
236 | case OP_SIN: | |
237 | { | |
238 | int32_t a = REINTERPRET_CAST(int32_t, s->gp_regs[reg_a]); | |
239 | float t = sinf(a * (1.0f / (M_PI * 4096.0f))); | |
240 | r = REINTERPRET_CAST(uint32_t, t); | |
241 | latency = LATENCY_SIN; | |
242 | D_EXEC(qemu_log("SIN a=%d t=%f, r=%08x\n", a, t, r)); | |
243 | } break; | |
244 | case OP_COS: | |
245 | { | |
246 | int32_t a = REINTERPRET_CAST(int32_t, s->gp_regs[reg_a]); | |
247 | float t = cosf(a * (1.0f / (M_PI * 4096.0f))); | |
248 | r = REINTERPRET_CAST(uint32_t, t); | |
249 | latency = LATENCY_COS; | |
250 | D_EXEC(qemu_log("COS a=%d t=%f, r=%08x\n", a, t, r)); | |
251 | } break; | |
252 | case OP_ABOVE: | |
253 | { | |
254 | float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]); | |
255 | float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]); | |
256 | float t = (a > b) ? 1.0f : 0.0f; | |
257 | r = REINTERPRET_CAST(uint32_t, t); | |
258 | latency = LATENCY_ABOVE; | |
259 | D_EXEC(qemu_log("ABOVE a=%f b=%f t=%f, r=%08x\n", a, b, t, r)); | |
260 | } break; | |
261 | case OP_EQUAL: | |
262 | { | |
263 | float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]); | |
264 | float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]); | |
265 | float t = (a == b) ? 1.0f : 0.0f; | |
266 | r = REINTERPRET_CAST(uint32_t, t); | |
267 | latency = LATENCY_EQUAL; | |
268 | D_EXEC(qemu_log("EQUAL a=%f b=%f t=%f, r=%08x\n", a, b, t, r)); | |
269 | } break; | |
270 | case OP_COPY: | |
271 | { | |
272 | r = s->gp_regs[reg_a]; | |
273 | latency = LATENCY_COPY; | |
274 | D_EXEC(qemu_log("COPY")); | |
275 | } break; | |
276 | case OP_IF: | |
277 | { | |
278 | float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]); | |
279 | float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]); | |
280 | uint32_t f = s->gp_regs[GPR_FLAGS]; | |
281 | float t = (f != 0) ? a : b; | |
282 | r = REINTERPRET_CAST(uint32_t, t); | |
283 | latency = LATENCY_IF; | |
284 | D_EXEC(qemu_log("IF f=%u a=%f b=%f t=%f, r=%08x\n", f, a, b, t, r)); | |
285 | } break; | |
286 | case OP_TSIGN: | |
287 | { | |
288 | float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]); | |
289 | float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]); | |
290 | float t = (b < 0) ? -a : a; | |
291 | r = REINTERPRET_CAST(uint32_t, t); | |
292 | latency = LATENCY_TSIGN; | |
293 | D_EXEC(qemu_log("TSIGN a=%f b=%f t=%f, r=%08x\n", a, b, t, r)); | |
294 | } break; | |
295 | case OP_QUAKE: | |
296 | { | |
297 | uint32_t a = s->gp_regs[reg_a]; | |
298 | r = 0x5f3759df - (a >> 1); | |
299 | latency = LATENCY_QUAKE; | |
300 | D_EXEC(qemu_log("QUAKE a=%d r=%08x\n", a, r)); | |
301 | } break; | |
302 | ||
303 | default: | |
6daf194d | 304 | error_report("milkymist_pfpu: unknown opcode %d", op); |
5ee18b9c MW |
305 | break; |
306 | } | |
307 | ||
308 | if (!reg_d) { | |
309 | D_EXEC(qemu_log("%04d %8s R%03d, R%03d <L=%d, E=%04d>\n", | |
310 | s->regs[R_PC], opcode_to_str[op], reg_a, reg_b, latency, | |
311 | s->regs[R_PC] + latency)); | |
312 | } else { | |
313 | D_EXEC(qemu_log("%04d %8s R%03d, R%03d <L=%d, E=%04d> -> R%03d\n", | |
314 | s->regs[R_PC], opcode_to_str[op], reg_a, reg_b, latency, | |
315 | s->regs[R_PC] + latency, reg_d)); | |
316 | } | |
317 | ||
318 | if (op == OP_VECTOUT) { | |
319 | return 0; | |
320 | } | |
321 | ||
322 | /* store output for this cycle */ | |
323 | if (reg_d) { | |
324 | uint32_t val = output_queue_remove(s); | |
325 | D_EXEC(qemu_log("R%03d <- 0x%08x\n", reg_d, val)); | |
326 | s->gp_regs[reg_d] = val; | |
327 | } | |
328 | ||
329 | output_queue_advance(s); | |
330 | ||
331 | /* store op output */ | |
332 | if (op != OP_NOP) { | |
333 | output_queue_insert(s, r, latency-1); | |
334 | } | |
335 | ||
336 | /* advance PC */ | |
337 | s->regs[R_PC]++; | |
338 | ||
339 | return 1; | |
340 | }; | |
341 | ||
342 | static void pfpu_start(MilkymistPFPUState *s) | |
343 | { | |
344 | int x, y; | |
345 | int i; | |
346 | ||
347 | for (y = 0; y <= s->regs[R_VMESHLAST]; y++) { | |
348 | for (x = 0; x <= s->regs[R_HMESHLAST]; x++) { | |
349 | D_EXEC(qemu_log("\nprocessing x=%d y=%d\n", x, y)); | |
350 | ||
351 | /* set current position */ | |
352 | s->gp_regs[GPR_X] = x; | |
353 | s->gp_regs[GPR_Y] = y; | |
354 | ||
355 | /* run microcode on this position */ | |
356 | i = 0; | |
357 | while (pfpu_decode_insn(s)) { | |
358 | /* decode at most MICROCODE_WORDS instructions */ | |
359 | if (i++ >= MICROCODE_WORDS) { | |
360 | error_report("milkymist_pfpu: too many instructions " | |
6daf194d | 361 | "executed in microcode. No VECTOUT?"); |
5ee18b9c MW |
362 | break; |
363 | } | |
364 | } | |
365 | ||
366 | /* reset pc for next run */ | |
367 | s->regs[R_PC] = 0; | |
368 | } | |
369 | } | |
370 | ||
371 | s->regs[R_VERTICES] = x * y; | |
372 | ||
373 | trace_milkymist_pfpu_pulse_irq(); | |
374 | qemu_irq_pulse(s->irq); | |
375 | } | |
376 | ||
377 | static inline int get_microcode_address(MilkymistPFPUState *s, uint32_t addr) | |
378 | { | |
379 | return (512 * s->regs[R_CODEPAGE]) + addr - MICROCODE_BEGIN; | |
380 | } | |
381 | ||
382 | static uint32_t pfpu_read(void *opaque, target_phys_addr_t addr) | |
383 | { | |
384 | MilkymistPFPUState *s = opaque; | |
385 | uint32_t r = 0; | |
386 | ||
387 | addr >>= 2; | |
388 | switch (addr) { | |
389 | case R_CTL: | |
390 | case R_MESHBASE: | |
391 | case R_HMESHLAST: | |
392 | case R_VMESHLAST: | |
393 | case R_CODEPAGE: | |
394 | case R_VERTICES: | |
395 | case R_COLLISIONS: | |
396 | case R_STRAYWRITES: | |
397 | case R_LASTDMA: | |
398 | case R_PC: | |
399 | case R_DREGBASE: | |
400 | case R_CODEBASE: | |
401 | r = s->regs[addr]; | |
402 | break; | |
403 | case GPR_BEGIN ... GPR_END: | |
404 | r = s->gp_regs[addr - GPR_BEGIN]; | |
405 | break; | |
406 | case MICROCODE_BEGIN ... MICROCODE_END: | |
407 | r = s->microcode[get_microcode_address(s, addr)]; | |
408 | break; | |
409 | ||
410 | default: | |
411 | error_report("milkymist_pfpu: read access to unknown register 0x" | |
412 | TARGET_FMT_plx, addr << 2); | |
413 | break; | |
414 | } | |
415 | ||
416 | trace_milkymist_pfpu_memory_read(addr << 2, r); | |
417 | ||
418 | return r; | |
419 | } | |
420 | ||
421 | static void | |
422 | pfpu_write(void *opaque, target_phys_addr_t addr, uint32_t value) | |
423 | { | |
424 | MilkymistPFPUState *s = opaque; | |
425 | ||
426 | trace_milkymist_pfpu_memory_write(addr, value); | |
427 | ||
428 | addr >>= 2; | |
429 | switch (addr) { | |
430 | case R_CTL: | |
431 | if (value & CTL_START_BUSY) { | |
432 | pfpu_start(s); | |
433 | } | |
434 | break; | |
435 | case R_MESHBASE: | |
436 | case R_HMESHLAST: | |
437 | case R_VMESHLAST: | |
438 | case R_CODEPAGE: | |
439 | case R_VERTICES: | |
440 | case R_COLLISIONS: | |
441 | case R_STRAYWRITES: | |
442 | case R_LASTDMA: | |
443 | case R_PC: | |
444 | case R_DREGBASE: | |
445 | case R_CODEBASE: | |
446 | s->regs[addr] = value; | |
447 | break; | |
448 | case GPR_BEGIN ... GPR_END: | |
449 | s->gp_regs[addr - GPR_BEGIN] = value; | |
450 | break; | |
451 | case MICROCODE_BEGIN ... MICROCODE_END: | |
452 | s->microcode[get_microcode_address(s, addr)] = value; | |
453 | break; | |
454 | ||
455 | default: | |
456 | error_report("milkymist_pfpu: write access to unknown register 0x" | |
457 | TARGET_FMT_plx, addr << 2); | |
458 | break; | |
459 | } | |
460 | } | |
461 | ||
462 | static CPUReadMemoryFunc * const pfpu_read_fn[] = { | |
463 | NULL, | |
464 | NULL, | |
465 | &pfpu_read, | |
466 | }; | |
467 | ||
468 | static CPUWriteMemoryFunc * const pfpu_write_fn[] = { | |
469 | NULL, | |
470 | NULL, | |
471 | &pfpu_write, | |
472 | }; | |
473 | ||
474 | static void milkymist_pfpu_reset(DeviceState *d) | |
475 | { | |
476 | MilkymistPFPUState *s = container_of(d, MilkymistPFPUState, busdev.qdev); | |
477 | int i; | |
478 | ||
479 | for (i = 0; i < R_MAX; i++) { | |
480 | s->regs[i] = 0; | |
481 | } | |
482 | for (i = 0; i < 128; i++) { | |
483 | s->gp_regs[i] = 0; | |
484 | } | |
485 | for (i = 0; i < MICROCODE_WORDS; i++) { | |
486 | s->microcode[i] = 0; | |
487 | } | |
488 | s->output_queue_pos = 0; | |
489 | for (i = 0; i < MAX_LATENCY; i++) { | |
490 | s->output_queue[i] = 0; | |
491 | } | |
492 | } | |
493 | ||
494 | static int milkymist_pfpu_init(SysBusDevice *dev) | |
495 | { | |
496 | MilkymistPFPUState *s = FROM_SYSBUS(typeof(*s), dev); | |
497 | int pfpu_regs; | |
498 | ||
499 | sysbus_init_irq(dev, &s->irq); | |
500 | ||
501 | pfpu_regs = cpu_register_io_memory(pfpu_read_fn, pfpu_write_fn, s, | |
502 | DEVICE_NATIVE_ENDIAN); | |
503 | sysbus_init_mmio(dev, MICROCODE_END * 4, pfpu_regs); | |
504 | ||
505 | return 0; | |
506 | } | |
507 | ||
508 | static const VMStateDescription vmstate_milkymist_pfpu = { | |
509 | .name = "milkymist-pfpu", | |
510 | .version_id = 1, | |
511 | .minimum_version_id = 1, | |
512 | .minimum_version_id_old = 1, | |
513 | .fields = (VMStateField[]) { | |
514 | VMSTATE_UINT32_ARRAY(regs, MilkymistPFPUState, R_MAX), | |
515 | VMSTATE_UINT32_ARRAY(gp_regs, MilkymistPFPUState, 128), | |
516 | VMSTATE_UINT32_ARRAY(microcode, MilkymistPFPUState, MICROCODE_WORDS), | |
517 | VMSTATE_INT32(output_queue_pos, MilkymistPFPUState), | |
518 | VMSTATE_UINT32_ARRAY(output_queue, MilkymistPFPUState, MAX_LATENCY), | |
519 | VMSTATE_END_OF_LIST() | |
520 | } | |
521 | }; | |
522 | ||
523 | static SysBusDeviceInfo milkymist_pfpu_info = { | |
524 | .init = milkymist_pfpu_init, | |
525 | .qdev.name = "milkymist-pfpu", | |
526 | .qdev.size = sizeof(MilkymistPFPUState), | |
527 | .qdev.vmsd = &vmstate_milkymist_pfpu, | |
528 | .qdev.reset = milkymist_pfpu_reset, | |
529 | }; | |
530 | ||
531 | static void milkymist_pfpu_register(void) | |
532 | { | |
533 | sysbus_register_withprop(&milkymist_pfpu_info); | |
534 | } | |
535 | ||
536 | device_init(milkymist_pfpu_register) |