diff options
Diffstat (limited to 'usr.bin/oemu/cpu.c')
| -rw-r--r-- | usr.bin/oemu/cpu.c | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/usr.bin/oemu/cpu.c b/usr.bin/oemu/cpu.c new file mode 100644 index 0000000..61568f2 --- /dev/null +++ b/usr.bin/oemu/cpu.c @@ -0,0 +1,146 @@ +/* + * Copyright (c) 2023-2025 Ian Marco Moffett and the Osmora Team. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of Hyra nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +#include <sys/param.h> +#include <stdlib.h> +#include <string.h> +#include <stdio.h> +#include <oemu/cpu.h> +#include <oemu/types.h> +#include <oemu/osmx64.h> + +/* + * Decode the INST_MOV_IMM instruction + * + * @cpu: CPU that is executing + * @inst: Instruction dword + */ +static void +cpu_mov_imm(struct oemu_cpu *cpu, inst_t *inst) +{ + struct cpu_regs *regs = &cpu->regs; + + if (inst->rd > NELEM(regs->xreg)) { + printf("bad register operand for 'mov'\n"); + return; + } + + regs->xreg[inst->rd] = inst->imm; + printf("#%d -> x%d\n", inst->imm, inst->rd); +} + +/* + * Decode the INST_INC instruction + * + * @cpu: CPU that is executing + * @inst: Instruction dword + */ +static void +cpu_inc(struct oemu_cpu *cpu, inst_t *inst) +{ + struct cpu_regs *regs = &cpu->regs; + imm_t imm; + + if (inst->rd > NELEM(regs->xreg)) { + printf("bad register operand for 'mov'\n"); + return; + } + + imm = regs->xreg[inst->rd]++; + printf("INC X%d [%x], new=%x\n", inst->rd, + imm, regs->xreg[inst->rd]); +} + +/* + * Decode the INST_DEC instruction + * + * @cpu: CPU that is executing + * @inst: Instruction dword + */ +static void +cpu_dec(struct oemu_cpu *cpu, inst_t *inst) +{ + struct cpu_regs *regs = &cpu->regs; + imm_t imm; + + if (inst->rd > NELEM(regs->xreg)) { + printf("bad register operand for 'mov'\n"); + return; + } + + imm = regs->xreg[inst->rd]--; + printf("DEC X%d [%x], new=%x\n", inst->rd, + imm, regs->xreg[inst->rd]); +} + +/* + * Reset a CPU to a default state + */ +void +cpu_reset(struct oemu_cpu *cpu) +{ + struct cpu_regs *regs; + + regs = &cpu->regs; + regs->ip = 0; + memset(regs->xreg, 0x0, sizeof(regs->xreg)); +} + +/* + * Main instruction execution loop. + */ +void +cpu_kick(struct oemu_cpu *cpu, struct sysmem *mem) +{ + struct cpu_regs *regs = &cpu->regs; + inst_t *inst; + uint8_t *memp = mem->mem; + + for (;;) { + inst = (inst_t *)&memp[regs->ip]; + + switch (inst->opcode) { + case INST_MOV_IMM: + cpu_mov_imm(cpu, inst); + break; + case INST_INC: + cpu_inc(cpu, inst); + break; + case INST_DEC: + cpu_dec(cpu, inst); + break; + } + + if (regs->ip >= MEMORY_SIZE) { + break; + } + + regs->ip += sizeof(*inst); + } +} |