diff options
Diffstat (limited to 'src/hw/misc/milkymist-pfpu.c')
| -rw-r--r-- | src/hw/misc/milkymist-pfpu.c | 548 |
1 files changed, 548 insertions, 0 deletions
diff --git a/src/hw/misc/milkymist-pfpu.c b/src/hw/misc/milkymist-pfpu.c new file mode 100644 index 0000000..08b604f --- /dev/null +++ b/src/hw/misc/milkymist-pfpu.c @@ -0,0 +1,548 @@ +/* + * 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) |
