/*
* 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/hw.h"
#include "hw/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
#define TYPE_MILKYMIST_PFPU "milkymist-pfpu"
#define MILKYMIST_PFPU(obj) \
OBJECT_CHECK(MilkymistPFPUState, (obj), TYPE_MILKYMIST_PFPU)
struct MilkymistPFPUState {
SysBusDevice parent_obj;
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, &a, 4);
cpu_physical_memory_write(dma_ptr + 4, &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 = MILKYMIST_PFPU(d);
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 = MILKYMIST_PFPU(dev);
sysbus_init_irq(dev, &s->irq);
memory_region_init_io(&s->regs_region, OBJECT(dev), &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,
.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 = TYPE_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)
