summaryrefslogtreecommitdiff
path: root/hw/milkymist-pfpu.c
blob: c347680ad74368debf93592fec01bfb2c3154f80 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
/*
 *  QEMU model of the Milkymist programmable FPU.
 *
 *  Copyright (c) 2010 Michael Walle <michael@walle.cc>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
 *
 *
 * Specification available at:
 *   http://www.milkymist.org/socdoc/pfpu.pdf
 *
 */

#include "hw.h"
#include "sysbus.h"
#include "trace.h"
#include "qemu/log.h"
#include "qemu/error-report.h"
#include <math.h>

/* #define TRACE_EXEC */

#ifdef TRACE_EXEC
#    define D_EXEC(x) x
#else
#    define D_EXEC(x)
#endif

enum {
    R_CTL = 0,
    R_MESHBASE,
    R_HMESHLAST,
    R_VMESHLAST,
    R_CODEPAGE,
    R_VERTICES,
    R_COLLISIONS,
    R_STRAYWRITES,
    R_LASTDMA,
    R_PC,
    R_DREGBASE,
    R_CODEBASE,
    R_MAX
};

enum {
    CTL_START_BUSY = (1<<0),
};

enum {
    OP_NOP = 0,
    OP_FADD,
    OP_FSUB,
    OP_FMUL,
    OP_FABS,
    OP_F2I,
    OP_I2F,
    OP_VECTOUT,
    OP_SIN,
    OP_COS,
    OP_ABOVE,
    OP_EQUAL,
    OP_COPY,
    OP_IF,
    OP_TSIGN,
    OP_QUAKE,
};

enum {
    GPR_X = 0,
    GPR_Y = 1,
    GPR_FLAGS = 2,
};

enum {
    LATENCY_FADD = 5,
    LATENCY_FSUB = 5,
    LATENCY_FMUL = 7,
    LATENCY_FABS = 2,
    LATENCY_F2I = 2,
    LATENCY_I2F = 3,
    LATENCY_VECTOUT = 0,
    LATENCY_SIN = 4,
    LATENCY_COS = 4,
    LATENCY_ABOVE = 2,
    LATENCY_EQUAL = 2,
    LATENCY_COPY = 2,
    LATENCY_IF = 2,
    LATENCY_TSIGN = 2,
    LATENCY_QUAKE = 2,
    MAX_LATENCY = 7
};

#define GPR_BEGIN       0x100
#define GPR_END         0x17f
#define MICROCODE_BEGIN 0x200
#define MICROCODE_END   0x3ff
#define MICROCODE_WORDS 2048

#define REINTERPRET_CAST(type, val) (*((type *)&(val)))

#ifdef TRACE_EXEC
static const char *opcode_to_str[] = {
    "NOP", "FADD", "FSUB", "FMUL", "FABS", "F2I", "I2F", "VECTOUT",
    "SIN", "COS", "ABOVE", "EQUAL", "COPY", "IF", "TSIGN", "QUAKE",
};
#endif

struct MilkymistPFPUState {
    SysBusDevice busdev;
    MemoryRegion regs_region;
    CharDriverState *chr;
    qemu_irq irq;

    uint32_t regs[R_MAX];
    uint32_t gp_regs[128];
    uint32_t microcode[MICROCODE_WORDS];

    int output_queue_pos;
    uint32_t output_queue[MAX_LATENCY];
};
typedef struct MilkymistPFPUState MilkymistPFPUState;

static inline hwaddr
get_dma_address(uint32_t base, uint32_t x, uint32_t y)
{
    return base + 8 * (128 * y + x);
}

static inline void
output_queue_insert(MilkymistPFPUState *s, uint32_t val, int pos)
{
    s->output_queue[(s->output_queue_pos + pos) % MAX_LATENCY] = val;
}

static inline uint32_t
output_queue_remove(MilkymistPFPUState *s)
{
    return s->output_queue[s->output_queue_pos];
}

static inline void
output_queue_advance(MilkymistPFPUState *s)
{
    s->output_queue[s->output_queue_pos] = 0;
    s->output_queue_pos = (s->output_queue_pos + 1) % MAX_LATENCY;
}

static int pfpu_decode_insn(MilkymistPFPUState *s)
{
    uint32_t pc = s->regs[R_PC];
    uint32_t insn = s->microcode[pc];
    uint32_t reg_a = (insn >> 18) & 0x7f;
    uint32_t reg_b = (insn >> 11) & 0x7f;
    uint32_t op = (insn >> 7) & 0xf;
    uint32_t reg_d = insn & 0x7f;
    uint32_t r = 0;
    int latency = 0;

    switch (op) {
    case OP_NOP:
        break;
    case OP_FADD:
    {
        float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]);
        float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]);
        float t = a + b;
        r = REINTERPRET_CAST(uint32_t, t);
        latency = LATENCY_FADD;
        D_EXEC(qemu_log("ADD a=%f b=%f t=%f, r=%08x\n", a, b, t, r));
    } break;
    case OP_FSUB:
    {
        float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]);
        float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]);
        float t = a - b;
        r = REINTERPRET_CAST(uint32_t, t);
        latency = LATENCY_FSUB;
        D_EXEC(qemu_log("SUB a=%f b=%f t=%f, r=%08x\n", a, b, t, r));
    } break;
    case OP_FMUL:
    {
        float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]);
        float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]);
        float t = a * b;
        r = REINTERPRET_CAST(uint32_t, t);
        latency = LATENCY_FMUL;
        D_EXEC(qemu_log("MUL a=%f b=%f t=%f, r=%08x\n", a, b, t, r));
    } break;
    case OP_FABS:
    {
        float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]);
        float t = fabsf(a);
        r = REINTERPRET_CAST(uint32_t, t);
        latency = LATENCY_FABS;
        D_EXEC(qemu_log("ABS a=%f t=%f, r=%08x\n", a, t, r));
    } break;
    case OP_F2I:
    {
        float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]);
        int32_t t = a;
        r = REINTERPRET_CAST(uint32_t, t);
        latency = LATENCY_F2I;
        D_EXEC(qemu_log("F2I a=%f t=%d, r=%08x\n", a, t, r));
    } break;
    case OP_I2F:
    {
        int32_t a = REINTERPRET_CAST(int32_t, s->gp_regs[reg_a]);
        float t = a;
        r = REINTERPRET_CAST(uint32_t, t);
        latency = LATENCY_I2F;
        D_EXEC(qemu_log("I2F a=%08x t=%f, r=%08x\n", a, t, r));
    } break;
    case OP_VECTOUT:
    {
        uint32_t a = cpu_to_be32(s->gp_regs[reg_a]);
        uint32_t b = cpu_to_be32(s->gp_regs[reg_b]);
        hwaddr dma_ptr =
            get_dma_address(s->regs[R_MESHBASE],
                    s->gp_regs[GPR_X], s->gp_regs[GPR_Y]);
        cpu_physical_memory_write(dma_ptr, (uint8_t *)&a, 4);
        cpu_physical_memory_write(dma_ptr + 4, (uint8_t *)&b, 4);
        s->regs[R_LASTDMA] = dma_ptr + 4;
        D_EXEC(qemu_log("VECTOUT a=%08x b=%08x dma=%08x\n", a, b, dma_ptr));
        trace_milkymist_pfpu_vectout(a, b, dma_ptr);
    } break;
    case OP_SIN:
    {
        int32_t a = REINTERPRET_CAST(int32_t, s->gp_regs[reg_a]);
        float t = sinf(a * (1.0f / (M_PI * 4096.0f)));
        r = REINTERPRET_CAST(uint32_t, t);
        latency = LATENCY_SIN;
        D_EXEC(qemu_log("SIN a=%d t=%f, r=%08x\n", a, t, r));
    } break;
    case OP_COS:
    {
        int32_t a = REINTERPRET_CAST(int32_t, s->gp_regs[reg_a]);
        float t = cosf(a * (1.0f / (M_PI * 4096.0f)));
        r = REINTERPRET_CAST(uint32_t, t);
        latency = LATENCY_COS;
        D_EXEC(qemu_log("COS a=%d t=%f, r=%08x\n", a, t, r));
    } break;
    case OP_ABOVE:
    {
        float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]);
        float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]);
        float t = (a > b) ? 1.0f : 0.0f;
        r = REINTERPRET_CAST(uint32_t, t);
        latency = LATENCY_ABOVE;
        D_EXEC(qemu_log("ABOVE a=%f b=%f t=%f, r=%08x\n", a, b, t, r));
    } break;
    case OP_EQUAL:
    {
        float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]);
        float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]);
        float t = (a == b) ? 1.0f : 0.0f;
        r = REINTERPRET_CAST(uint32_t, t);
        latency = LATENCY_EQUAL;
        D_EXEC(qemu_log("EQUAL a=%f b=%f t=%f, r=%08x\n", a, b, t, r));
    } break;
    case OP_COPY:
    {
        r = s->gp_regs[reg_a];
        latency = LATENCY_COPY;
        D_EXEC(qemu_log("COPY"));
    } break;
    case OP_IF:
    {
        float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]);
        float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]);
        uint32_t f = s->gp_regs[GPR_FLAGS];
        float t = (f != 0) ? a : b;
        r = REINTERPRET_CAST(uint32_t, t);
        latency = LATENCY_IF;
        D_EXEC(qemu_log("IF f=%u a=%f b=%f t=%f, r=%08x\n", f, a, b, t, r));
    } break;
    case OP_TSIGN:
    {
        float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]);
        float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]);
        float t = (b < 0) ? -a : a;
        r = REINTERPRET_CAST(uint32_t, t);
        latency = LATENCY_TSIGN;
        D_EXEC(qemu_log("TSIGN a=%f b=%f t=%f, r=%08x\n", a, b, t, r));
    } break;
    case OP_QUAKE:
    {
        uint32_t a = s->gp_regs[reg_a];
        r = 0x5f3759df - (a >> 1);
        latency = LATENCY_QUAKE;
        D_EXEC(qemu_log("QUAKE a=%d r=%08x\n", a, r));
    } break;

    default:
        error_report("milkymist_pfpu: unknown opcode %d", op);
        break;
    }

    if (!reg_d) {
        D_EXEC(qemu_log("%04d %8s R%03d, R%03d <L=%d, E=%04d>\n",
                    s->regs[R_PC], opcode_to_str[op], reg_a, reg_b, latency,
                    s->regs[R_PC] + latency));
    } else {
        D_EXEC(qemu_log("%04d %8s R%03d, R%03d <L=%d, E=%04d> -> R%03d\n",
                    s->regs[R_PC], opcode_to_str[op], reg_a, reg_b, latency,
                    s->regs[R_PC] + latency, reg_d));
    }

    if (op == OP_VECTOUT) {
        return 0;
    }

    /* store output for this cycle */
    if (reg_d) {
        uint32_t val = output_queue_remove(s);
        D_EXEC(qemu_log("R%03d <- 0x%08x\n", reg_d, val));
        s->gp_regs[reg_d] = val;
    }

    output_queue_advance(s);

    /* store op output */
    if (op != OP_NOP) {
        output_queue_insert(s, r, latency-1);
    }

    /* advance PC */
    s->regs[R_PC]++;

    return 1;
};

static void pfpu_start(MilkymistPFPUState *s)
{
    int x, y;
    int i;

    for (y = 0; y <= s->regs[R_VMESHLAST]; y++) {
        for (x = 0; x <= s->regs[R_HMESHLAST]; x++) {
            D_EXEC(qemu_log("\nprocessing x=%d y=%d\n", x, y));

            /* set current position */
            s->gp_regs[GPR_X] = x;
            s->gp_regs[GPR_Y] = y;

            /* run microcode on this position */
            i = 0;
            while (pfpu_decode_insn(s)) {
                /* decode at most MICROCODE_WORDS instructions */
                if (i++ >= MICROCODE_WORDS) {
                    error_report("milkymist_pfpu: too many instructions "
                            "executed in microcode. No VECTOUT?");
                    break;
                }
            }

            /* reset pc for next run */
            s->regs[R_PC] = 0;
        }
    }

    s->regs[R_VERTICES] = x * y;

    trace_milkymist_pfpu_pulse_irq();
    qemu_irq_pulse(s->irq);
}

static inline int get_microcode_address(MilkymistPFPUState *s, uint32_t addr)
{
    return (512 * s->regs[R_CODEPAGE]) + addr - MICROCODE_BEGIN;
}

static uint64_t pfpu_read(void *opaque, hwaddr addr,
                          unsigned size)
{
    MilkymistPFPUState *s = opaque;
    uint32_t r = 0;

    addr >>= 2;
    switch (addr) {
    case R_CTL:
    case R_MESHBASE:
    case R_HMESHLAST:
    case R_VMESHLAST:
    case R_CODEPAGE:
    case R_VERTICES:
    case R_COLLISIONS:
    case R_STRAYWRITES:
    case R_LASTDMA:
    case R_PC:
    case R_DREGBASE:
    case R_CODEBASE:
        r = s->regs[addr];
        break;
    case GPR_BEGIN ... GPR_END:
        r = s->gp_regs[addr - GPR_BEGIN];
        break;
    case MICROCODE_BEGIN ...  MICROCODE_END:
        r = s->microcode[get_microcode_address(s, addr)];
        break;

    default:
        error_report("milkymist_pfpu: read access to unknown register 0x"
                TARGET_FMT_plx, addr << 2);
        break;
    }

    trace_milkymist_pfpu_memory_read(addr << 2, r);

    return r;
}

static void pfpu_write(void *opaque, hwaddr addr, uint64_t value,
                       unsigned size)
{
    MilkymistPFPUState *s = opaque;

    trace_milkymist_pfpu_memory_write(addr, value);

    addr >>= 2;
    switch (addr) {
    case R_CTL:
        if (value & CTL_START_BUSY) {
            pfpu_start(s);
        }
        break;
    case R_MESHBASE:
    case R_HMESHLAST:
    case R_VMESHLAST:
    case R_CODEPAGE:
    case R_VERTICES:
    case R_COLLISIONS:
    case R_STRAYWRITES:
    case R_LASTDMA:
    case R_PC:
    case R_DREGBASE:
    case R_CODEBASE:
        s->regs[addr] = value;
        break;
    case GPR_BEGIN ...  GPR_END:
        s->gp_regs[addr - GPR_BEGIN] = value;
        break;
    case MICROCODE_BEGIN ...  MICROCODE_END:
        s->microcode[get_microcode_address(s, addr)] = value;
        break;

    default:
        error_report("milkymist_pfpu: write access to unknown register 0x"
                TARGET_FMT_plx, addr << 2);
        break;
    }
}

static const MemoryRegionOps pfpu_mmio_ops = {
    .read = pfpu_read,
    .write = pfpu_write,
    .valid = {
        .min_access_size = 4,
        .max_access_size = 4,
    },
    .endianness = DEVICE_NATIVE_ENDIAN,
};

static void milkymist_pfpu_reset(DeviceState *d)
{
    MilkymistPFPUState *s = container_of(d, MilkymistPFPUState, busdev.qdev);
    int i;

    for (i = 0; i < R_MAX; i++) {
        s->regs[i] = 0;
    }
    for (i = 0; i < 128; i++) {
        s->gp_regs[i] = 0;
    }
    for (i = 0; i < MICROCODE_WORDS; i++) {
        s->microcode[i] = 0;
    }
    s->output_queue_pos = 0;
    for (i = 0; i < MAX_LATENCY; i++) {
        s->output_queue[i] = 0;
    }
}

static int milkymist_pfpu_init(SysBusDevice *dev)
{
    MilkymistPFPUState *s = FROM_SYSBUS(typeof(*s), dev);

    sysbus_init_irq(dev, &s->irq);

    memory_region_init_io(&s->regs_region, &pfpu_mmio_ops, s,
            "milkymist-pfpu", MICROCODE_END * 4);
    sysbus_init_mmio(dev, &s->regs_region);

    return 0;
}

static const VMStateDescription vmstate_milkymist_pfpu = {
    .name = "milkymist-pfpu",
    .version_id = 1,
    .minimum_version_id = 1,
    .minimum_version_id_old = 1,
    .fields      = (VMStateField[]) {
        VMSTATE_UINT32_ARRAY(regs, MilkymistPFPUState, R_MAX),
        VMSTATE_UINT32_ARRAY(gp_regs, MilkymistPFPUState, 128),
        VMSTATE_UINT32_ARRAY(microcode, MilkymistPFPUState, MICROCODE_WORDS),
        VMSTATE_INT32(output_queue_pos, MilkymistPFPUState),
        VMSTATE_UINT32_ARRAY(output_queue, MilkymistPFPUState, MAX_LATENCY),
        VMSTATE_END_OF_LIST()
    }
};

static void milkymist_pfpu_class_init(ObjectClass *klass, void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);
    SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);

    k->init = milkymist_pfpu_init;
    dc->reset = milkymist_pfpu_reset;
    dc->vmsd = &vmstate_milkymist_pfpu;
}

static const TypeInfo milkymist_pfpu_info = {
    .name          = "milkymist-pfpu",
    .parent        = TYPE_SYS_BUS_DEVICE,
    .instance_size = sizeof(MilkymistPFPUState),
    .class_init    = milkymist_pfpu_class_init,
};

static void milkymist_pfpu_register_types(void)
{
    type_register_static(&milkymist_pfpu_info);
}

type_init(milkymist_pfpu_register_types)