8 files changed, 661 insertions, 0 deletions
diff --git a/triscv/src/common.c b/triscv/src/common.c
new file mode 100644
index 0000000..e73d76e
--- /dev/null
+++ b/triscv/src/common.c
@@ -0,0 +1,13 @@
+#include <triscv/common.h>
+
+static const char *err_strs[] = {
+	[OK] = "OK",
+	[ERR_FULL] = "full",
+	[ERR_EXISTS] = "exists",
+	[ERR_OOB] = "out of bounds"
+};
+
+const char *err_str(stat_t s)
+{
+	return err_strs[s];
+}
diff --git a/triscv/src/cpu.c b/triscv/src/cpu.c
new file mode 100644
index 0000000..54e892c
--- /dev/null
+++ b/triscv/src/cpu.c
@@ -0,0 +1,281 @@
+#include <triscv/cpu.h>
+#include <triscv/mmu.h>
+#include <triscv/csr.h>
+
+struct cpu {
+	vm_t pc;
+	struct mmu *mmu;
+	struct tmb *tmb;
+
+	enum mode {
+		MMODE = 0, SMODE = 1, UMODE = 2
+	} mode;
+
+	/* we only have 81 registers, but 3^4 can be encoded in 2^8, and this
+	 * way we can directly use the BCT as an index, speeding things up a bit
+	 *
+	 * csrs are too big, probably not worth it */
+	tri_t gpr[256];
+
+	/* 6561 M-mode, 6561 S-mode, 6561 U-mode, maybe? so ixxxxxxxx is
+	 * reserved for M, 0xxxxxx for S, 1xxxx... for U. Just have to map them
+	 * to decimal/binary in a somewhat sensible manner */
+	/* value */
+	tri_t csr[19683];
+	/* write trit, all csrs are readable? */
+	tri_t csrw[19683];
+};
+
+static size_t get_csr_num(tri_t csr)
+{
+	return tri_to(csr) + 9841;
+}
+
+static tri_t get_csr(struct cpu *cpu, size_t i)
+{
+	size_t max_csr = cpu->mode * 6561;
+	if (i < max_csr)
+		return 0; /* illegal access, should maybe also raise an interrupt? */
+
+	return cpu->csr[i];
+}
+
+static void set_csr(struct cpu *cpu, size_t i, tri_t t)
+{
+	size_t max_csr = cpu->mode * 6561;
+	if (i < max_csr)
+		return;
+
+	tri_t csr = cpu->csr[i];
+	tri_t w = cpu->csrw[i];
+
+	/* clear out trits we don't have write permission for*/
+	t   &=  w;
+	csr &= ~w;
+	csr |= t;
+
+	cpu->csr[i] = csr;
+}
+
+static tri_t get_gpr(struct cpu *cpu, tri_t i)
+{
+	/* could also add in check that i is in range, though that would
+	 * probably add a fair bit of overhead */
+	if (i == 0)
+		return 0;
+
+	return cpu->gpr[i];
+}
+
+static void set_gpr(struct cpu *cpu, tri_t i, tri_t t)
+{
+	if (i == 0)
+		return;
+
+	cpu->gpr[i] = t;
+}
+
+static void csr_init(struct cpu *cpu)
+{
+	cpu->csr[CSR_MPOWER] = 0;
+	cpu->csrw[CSR_MPOWER] = RW_MPOWER;
+}
+
+struct cpu *cpu_create(struct mmu *mmu, struct tmb *tmb)
+{
+	struct cpu *cpu = calloc(1, sizeof(struct cpu));
+	cpu->mmu = mmu;
+	cpu->tmb = tmb;
+	csr_init(cpu);
+	return cpu;
+}
+
+void cpu_destroy(struct cpu *cpu)
+{
+	free(cpu);
+}
+
+static tri_t get_rd(tri_t i)
+{
+	i = tri_sr(i, 5);
+	return tri_mask(i, 4);
+}
+
+static tri_t get_rs1(tri_t i)
+{
+	i = tri_sr(i, 14);
+	return tri_mask(i, 4);
+}
+
+static tri_t get_rs2(tri_t i)
+{
+	i = tri_sr(i, 18);
+	return tri_mask(i, 4);
+}
+
+static tri_t get_imm4(tri_t i)
+{
+	i = tri_sr(i, 5);
+	return tri_mask(i, 4);
+}
+
+static tri_t get_imm5(tri_t i)
+{
+	i = tri_sr(i, 22);
+	return tri_mask(i, 5);
+}
+
+static tri_t get_imm9(tri_t i)
+{
+	i = tri_sr(i, 18);
+	return tri_mask(i, 9);
+}
+
+static tri_t get_imm18(tri_t i)
+{
+	i = tri_sr(i, 9);
+	return tri_mask(i, 18);
+}
+
+static tri_t get_fn0(tri_t i)
+{
+	i = tri_sr(i, 9);
+	return tri_mask(i, 5);
+}
+
+/** @todo these macros should be ripped out into some common repository for
+ * reuse in an assembler */
+/* ALL HARDCODED VALUES ARE PLACEHOLDERS FOR NOW */
+
+/* 0 */
+#define OP_IMM 0b0000000000
+static void do_op_imm(struct cpu *cpu, tri_t i)
+{
+	tri_t rs1 = get_rs1(i);
+	tri_t rd = get_rd(i);
+
+	tri_t src = get_gpr(cpu, rs1);
+	tri_t imm9 = get_imm9(i);
+	tri_t fn0 = get_fn0(i);
+
+#define ADDI 0
+	switch (fn0) {
+	case ADDI: {
+		tri_t r = tri_add(src, imm9);
+		set_gpr(cpu, rd, r);
+		break;
+	}
+	default: fprintf(stderr, "illegal/unimplemented OP_IMM at %lx,"
+				 "aborting\n", cpu->pc);
+		 abort();
+	}
+
+	cpu->pc += 3;
+}
+
+/* 1 */
+#define SYSTEM 0b0000000001
+static void do_system(struct cpu *cpu, tri_t i)
+{
+	size_t rs1 = get_rs1(i);
+	size_t rd = get_rd(i);
+
+	tri_t src = get_gpr(cpu, rs1);
+	tri_t csr = get_imm9(i);
+	tri_t fn0 = get_fn0(i);
+
+
+#define CSRRW 0
+	switch (fn0) {
+	case CSRRW: {
+		/* read existing value and replace it with rs1 */
+		size_t n = get_csr_num(csr);
+		tri_t c = get_csr(cpu, n);
+		set_csr(cpu, n, src);
+		set_gpr(cpu, rd, c);
+		break;
+	}
+
+	default: fprintf(stderr, "illegal/unimplemented SYSTEM at %lx,"
+				 "aborting\n", cpu->pc);
+		 abort();
+	}
+
+	cpu->pc += 3;
+}
+
+/* -1 */
+#define STORE 0b0000000010
+static void do_store(struct cpu *cpu, tri_t i)
+{
+	size_t rs1 = get_rs1(i);
+	size_t rs2 = get_rs2(i);
+
+	tri_t src = get_gpr(cpu, rs2);
+	tri_t base = get_gpr(cpu, rs1);
+	tri_t imm4 = get_imm4(i);
+	tri_t imm5 = get_imm5(i);
+	tri_t fn0 = get_fn0(i);
+
+	tri_t imm = tri_sl(imm5, 4) | imm4;
+
+	/* should maybe check that there's zeroes in other trits in fn0? */
+	int w = tri_get_trit(fn0, 4);
+
+	/* somewhat unsure if mmu should function in trinary or binary at this
+	 * point */
+	tri_t addr = tri_add(base, imm);
+	vm_t a = tri_to(addr);
+
+	switch (w) {
+	case 0: mmu_write1(cpu, cpu->mmu, a, src); break;
+	case 1: mmu_write3(cpu, cpu->mmu, a, src); break;
+	default:
+		/* illegal value */
+		abort();
+	}
+
+	cpu->pc += 3;
+}
+
+/* 3 */
+#define LUI 0b0000000100
+static void do_lui(struct cpu *cpu, tri_t i)
+{
+	size_t rd = get_rd(i);
+	tri_t imm18 = get_imm18(i);
+	set_gpr(cpu, rd, tri_sl(imm18, 9));
+	cpu->pc += 3;
+}
+
+void cpu_reset(struct cpu *cpu)
+{
+	csr_init(cpu);
+}
+
+void cpu_run(struct cpu *cpu, vm_t start)
+{
+	cpu->pc = start;
+
+	/* run while the shutdown trit is zero */
+	while (!(cpu->csr[CSR_MPOWER] & 0b1100)) {
+		tri_t i = mmu_read3(cpu, cpu->mmu, cpu->pc);
+		/** @todo check for raised interrupts, illegal addr etc. */
+
+		/* check lowest five trits to determine opcode */
+		switch (tri_mask(i, 5)) {
+		case LUI:    do_lui(cpu, i);    break;
+		case STORE:  do_store(cpu, i);  break;
+		case SYSTEM: do_system(cpu, i); break;
+		case OP_IMM: do_op_imm(cpu, i); break;
+		default: /** @todo raise illegal instruction exception */
+			     fprintf(stderr, "illegal/unimplemented "
+					     "instruction at %lx, aborting\n",
+					     cpu->pc);
+			     abort();
+			     break;
+		}
+
+		/* do_* is responsible for updating pc */
+	}
+}
diff --git a/triscv/src/main.c b/triscv/src/main.c
new file mode 100644
index 0000000..7acc958
--- /dev/null
+++ b/triscv/src/main.c
@@ -0,0 +1,62 @@
+#include <triscv/uart.h>
+#include <triscv/cpu.h>
+#include <triscv/mmu.h>
+#include <triscv/tmb.h>
+#include <triscv/mem.h>
+
+#define OPCODE(t) (t)
+#define RD(t) ((t) << 10)
+#define RS1(t) ((t) << 28)
+#define RS2(t) ((t) << 36)
+#define IMM4(t) ((t) << 10)
+#define IMM5(t) ((t) << 44)
+#define IMM9(t) ((t) << 36)
+#define IMM18(t) ((t) << 18)
+
+static const tri_t prog[] = {
+	/* li x1, '0' (48) */
+	/* or in this case, lui x1, 0, addi x1, 48 */
+	OPCODE(0b0100ULL) | RD(0b01ULL) | IMM18(0b0ULL),
+	OPCODE(0b0000ULL) | RD(0b01ULL) | RS1(0b01ULL) | IMM9(0b0110100100ULL),
+	/* li x2, 19683 (uart base reg) */
+	OPCODE(0b0100ULL) | RD(0b10ULL) | IMM18(0b1ULL),
+	OPCODE(0b0000ULL) | RD(0b10ULL) | RS1(0b10ULL) | IMM9(0ULL),
+	/* sw x1, 0(x2) */
+	OPCODE(0b0010ULL) | RS2(0b01ULL) | RS1(0b10ULL),
+	/* li x1, 3 (mpower)*/
+	OPCODE(0b0100ULL) | RD(0b01ULL),
+	OPCODE(0b0000ULL) | RD(0b01ULL) | RS1(0b01ULL) | IMM9(0b0100ULL),
+	/* csrrw mpower, x0, x1 */
+	/* mpower = -9841, which is then internally converted to 0 */
+	/* NOT FINAL CSR VALUE */
+	OPCODE(0b0001ULL) | RD(0b00ULL) | RS1(0b01ULL) | IMM9(0b101010101010101010UL)
+};
+
+int main()
+{
+	/* add memory regions etc. */
+	struct mmu *mmu = mmu_create();
+
+	/* map one trinary page */
+	struct mem *mem = mem_create(19683);
+	mem_init(mem, prog, 8);
+	mmu_map_dev(mmu, 0, mem_dev(mem));
+
+	struct uart *uart = uart_create();
+	mmu_map_dev(mmu, 19683, uart_dev(uart));
+
+	struct tmb *tmb = tmb_create();
+
+	/* one cpu for each core we want */
+	struct cpu *cpu = cpu_create(mmu, tmb);
+
+	cpu_run(cpu, 0);
+
+	uart_destroy(uart);
+	cpu_destroy(cpu);
+	tmb_destroy(tmb);
+	mmu_destroy(mmu);
+	mem_destroy(mem);
+
+	return 0;
+}
diff --git a/triscv/src/mem.c b/triscv/src/mem.c
new file mode 100644
index 0000000..5d70896
--- /dev/null
+++ b/triscv/src/mem.c
@@ -0,0 +1,79 @@
+#include <triscv/mem.h>
+#include <string.h>
+
+struct mem {
+	size_t size;
+	uint32_t buf[];
+};
+
+struct mem *mem_create(size_t size)
+{
+	struct mem *mem = calloc(1, sizeof(struct mem) + size * sizeof(mem->buf[0]));
+	mem->size = size;
+	return mem;
+}
+
+void mem_destroy(struct mem *mem)
+{
+	free(mem);
+}
+
+void mem_init(struct mem *mem, const void *buf, size_t len)
+{
+	assert((len * 3) < mem->size);
+	for (size_t i = 0; i < len * 3; i += 3) {
+		tri_t t = ((tri_t *)buf)[i / 3];
+		mem->buf[i + 0] = tri_mask(t, 9);
+		t = tri_sr(t, 9);
+
+		mem->buf[i + 1] = tri_mask(t, 9);
+		t = tri_sr(t, 9);
+
+		mem->buf[i + 2] = tri_mask(t, 9);
+	}
+}
+
+static void mem_write1(struct cpu *cpu, struct mem *mem, pm_t addr, tri_t t)
+{
+	(void)cpu;
+	(void)mem;
+	(void)addr;
+	(void)t;
+}
+
+static void mem_write3(struct cpu *cpu, struct mem *mem, pm_t addr, tri_t t)
+{
+	(void)cpu;
+	(void)mem;
+	(void)addr;
+	(void)t;
+}
+
+static tri_t mem_read1(struct cpu *cpu, struct mem *mem, pm_t addr)
+{
+	(void)cpu;
+	tri_t t = (tri_t)mem->buf[addr];
+	return tri_mask(t, 9);
+}
+
+static tri_t mem_read3(struct cpu *cpu, struct mem *mem, pm_t addr)
+{
+	(void)cpu;
+	/* not necessarily ideal, but I guess it works for now */
+	tri_t t0 = mem_read1(cpu, mem, addr + 0);
+	tri_t t1 = mem_read1(cpu, mem, addr + 1);
+	tri_t t2 = mem_read1(cpu, mem, addr + 2);
+	return t0 | tri_sl(t1, 9) | tri_sl(t2, 18);
+}
+
+struct dev mem_dev(struct mem *mem)
+{
+	return (struct dev){
+		.dev = mem,
+		.size = mem->size,
+		.write1 = (dev_write1_t)mem_write1,
+		.write3 = (dev_write3_t)mem_write3,
+		.read1 = (dev_read1_t)mem_read1,
+		.read3 = (dev_read3_t)mem_read3
+	};
+}
diff --git a/triscv/src/mmu.c b/triscv/src/mmu.c
new file mode 100644
index 0000000..c73f91d
--- /dev/null
+++ b/triscv/src/mmu.c
@@ -0,0 +1,151 @@
+#include <triscv/mmu.h>
+
+struct tlb_map {
+	vm_t from;
+	pm_t to;
+	bool valid;
+};
+
+struct dev_map {
+	pm_t start;
+	struct dev dev;
+};
+
+/* completely arbitrary value */
+#define MMU_SIZE 1024
+#define MAX_DEVS 16
+struct mmu {
+	/* virtual -> physical */
+	struct tlb_map tlb[MMU_SIZE];
+
+	/* physical to dev */
+	struct dev_map dev[MAX_DEVS];
+	size_t devs;
+
+	/* whether we should treat incoming addresses as virtual or physical */
+	bool translate;
+};
+
+struct mmu *mmu_create()
+{
+	/** @todo map some backing memory as well */
+	return calloc(1, sizeof(struct mmu));
+}
+
+void mmu_destroy(struct mmu *mmu)
+{
+	free(mmu);
+}
+
+static struct dev_map *mmu_find_dev_map(struct mmu *mmu, pm_t addr)
+{
+	for (size_t i = 0; i < mmu->devs; ++i) {
+		struct dev_map *d = &mmu->dev[i];
+		if (d->start > addr)
+			continue;
+
+		/* slightly tricky off by one here */
+		if (d->dev.size <= (addr - d->start))
+			continue;
+
+		return d;
+	}
+
+	return NULL;
+}
+
+stat_t mmu_map_dev(struct mmu *mmu, pm_t start, struct dev dev)
+{
+	/** @todo return status or something */
+	if (mmu->devs == MAX_DEVS)
+		return ERR_FULL;
+
+	if (mmu_find_dev_map(mmu, start))
+		return ERR_EXISTS;
+
+	struct dev_map *d = &mmu->dev[mmu->devs++];
+	d->dev = dev;
+	d->start = start;
+	return OK;
+}
+
+void mmu_enable(struct mmu *mmu)
+{
+	mmu->translate = true;
+}
+
+void mmu_disable(struct mmu *mmu)
+{
+	mmu->translate = false;
+}
+
+static bool mmu_translate(struct cpu *cpu, struct mmu *mmu, vm_t *addr)
+{
+	(void)cpu;
+	(void)mmu;
+	(void)addr;
+	/** @todo raise segfault if addr is not allowed */
+	return true;
+}
+
+void mmu_write1(struct cpu *cpu, struct mmu *mmu, vm_t addr, tri_t t)
+{
+	if (mmu->translate) {
+		if (!mmu_translate(cpu, mmu, &addr))
+			return;
+	}
+
+	struct dev_map *d = mmu_find_dev_map(mmu, addr);
+	if (!d || !d->dev.write1) {
+		/** @todo raise bus (?) error */
+	}
+
+	d->dev.write1(cpu, d->dev.dev, addr - d->start, t);
+}
+
+void mmu_write3(struct cpu *cpu, struct mmu *mmu, vm_t addr, tri_t t)
+{
+	if (mmu->translate) {
+		if (!mmu_translate(cpu, mmu, &addr))
+			return;
+	}
+
+	struct dev_map *d = mmu_find_dev_map(mmu, addr);
+	if (!d || !d->dev.write3) {
+		/** @todo raise bus error */
+	}
+
+	d->dev.write3(cpu, d->dev.dev, addr - d->start, t);
+}
+
+tri_t mmu_read1(struct cpu *cpu, struct mmu *mmu, vm_t addr)
+{
+	if (mmu->translate) {
+		if (!mmu_translate(cpu, mmu, &addr))
+			return 0;
+	}
+
+	struct dev_map *d = mmu_find_dev_map(mmu, addr);
+	if (!d || !d->dev.read1) {
+		/** @todo raise bus error */
+		return 0;
+	}
+
+	return d->dev.read1(cpu, d->dev.dev, addr - d->start);
+}
+
+tri_t mmu_read3(struct cpu *cpu, struct mmu *mmu, vm_t addr)
+{
+	if (mmu->translate) {
+		if (!mmu_translate(cpu, mmu, &addr))
+			return 0;
+	}
+
+	struct dev_map *d = mmu_find_dev_map(mmu, addr);
+	if (!d || !d->dev.read3) {
+		/** @todo raise bus error */
+		return 0;
+	}
+
+	return d->dev.read3(cpu, d->dev.dev, addr - d->start);
+}
diff --git a/triscv/src/source.mk b/triscv/src/source.mk
new file mode 100644
index 0000000..3b8724f
--- /dev/null
+++ b/triscv/src/source.mk
@@ -0,0 +1,2 @@
+SRC_LOCAL	!= echo src/*.c
+TRISCV_SOURCES	+= $(SRC_LOCAL)
diff --git a/triscv/src/tmb.c b/triscv/src/tmb.c
new file mode 100644
index 0000000..3f6c037
--- /dev/null
+++ b/triscv/src/tmb.c
@@ -0,0 +1,29 @@
+#include <triscv/tmb.h>
+
+struct map {
+	vm_t to;
+	tri_t val;
+	size_t width;
+	bool valid;
+};
+
+#define TMB_SIZE 3
+struct tmb {
+	struct map map[TMB_SIZE];
+};
+
+struct tmb *tmb_create()
+{
+	return calloc(1, sizeof(struct tmb));
+}
+
+void tmb_destroy(struct tmb *tmb)
+{
+	free(tmb);
+}
+
+size_t tmb_size(struct cpu *cpu)
+{
+	(void)cpu;
+	return TMB_SIZE;
+}
diff --git a/triscv/src/uart.c b/triscv/src/uart.c
new file mode 100644
index 0000000..492f0dd
--- /dev/null
+++ b/triscv/src/uart.c
@@ -0,0 +1,44 @@
+#include <triscv/uart.h>
+#include <utf9.h>
+
+struct uart {
+	/* guess this doesn't need much for now, at least until I add some state
+	 * stuff to it */
+};
+
+struct uart *uart_create()
+{
+	return calloc(1, sizeof(struct uart));
+}
+
+void uart_destroy(struct uart *uart)
+{
+	free(uart);
+}
+
+static void uart_write1(struct cpu *cpu, struct uart *uart, pm_t addr, tri_t t)
+{
+	(void)cpu;
+	(void)uart;
+	(void)addr;
+
+#define U8_LEN 16
+	uint8_t u8[U8_LEN] = {0};
+	size_t u9_read = 0;
+	size_t l = utf9_to_utf8(u8, U8_LEN, &t, 1, &u9_read);
+
+	for (size_t i = 0; i < l; ++i)
+		putchar(u8[i]);
+}
+
+struct dev uart_dev(struct uart *uart)
+{
+	return (struct dev){
+		.dev = uart,
+		.size = 1,
+		.write1 = (dev_write1_t)uart_write1,
+		.write3 = NULL, /* illegal */
+		.read1 = NULL, /* not supported for now */
+		.read3 = NULL
+	};
+}