242 lines
No EOL
6 KiB
C
242 lines
No EOL
6 KiB
C
#include "vm.h"
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#include <stdio.h>
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static void cmd_copy(CommandInfo *info)
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{
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info->output = info->input0;
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}
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static void cmd_load(Process *p, CommandInfo *info)
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{
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info->output = vm_read_byte(p, info->input0);
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}
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static void cmd_store(Process *p, CommandInfo *info)
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{
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vm_write_byte(p, info->input0, info->input1);
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info->output = info->input1;
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}
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static void cmd_spget(Process *p, CommandInfo *info)
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{
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info->output = p->stackPointer;
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}
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static void cmd_spset(Process *p, CommandInfo *info)
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{
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info->output = p->stackPointer = info->input0;
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}
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static void cmd_bpget(Process *p, CommandInfo *info)
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{
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info->output = p->basePointer;
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}
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static void cmd_bpset(Process *p, CommandInfo *info)
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{
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info->output = p->basePointer = info->input0;
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}
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static void cmd_cpget(Process *p, CommandInfo *info)
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{
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info->output = p->codePointer + info->additional;
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}
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static inline int16_t makeSigned(uint16_t val)
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{
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return *((int16_t*)&val);
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}
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static void cmd_get(Process *p, CommandInfo *info)
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{
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info->output = p->stack[p->basePointer + makeSigned(info->input0)];
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}
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static void cmd_set(Process *p, CommandInfo *info)
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{
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info->output = p->stack[p->basePointer + makeSigned(info->input0)] = info->input1;
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}
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static void cmd_math(CommandInfo *info)
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{
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switch(info->additional)
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{
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// IMPORTANT:
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// input1 - input0 because then input0 can be a fixed value
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#define S(name, op) case name: info->output = info->input1 op info->input0; break;
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S(VM_MATH_ADD, +)
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S(VM_MATH_SUB, -)
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S(VM_MATH_MUL, *)
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S(VM_MATH_DIV, /)
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S(VM_MATH_MOD, %)
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S(VM_MATH_AND, &)
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S(VM_MATH_OR, |)
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S(VM_MATH_XOR, ^)
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#undef S
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case VM_MATH_NOT: info->output = ~info->input0; break;
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default: vm_assert(0, "Invalid instruction: MATH command not defined."); break;
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}
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}
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int vm_step_process(Process *process)
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{
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vm_assert(process != NULL, "process must not be NULL.");
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Instruction instr = process->module->code[process->codePointer++];
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int exec = 1;
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switch(instr.execZ)
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{
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case VM_EXEC_X:
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/* Don't modify execution. */
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break;
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case VM_EXEC_0:
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if((process->flags & VM_FLAG_Z) != 0)
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exec = 0;
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break;
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case VM_EXEC_1:
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if((process->flags & VM_FLAG_Z) == 0)
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exec = 0;
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break;
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default:
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vm_assert(0, "Invalid instruction: execZ undefined.");
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break;
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}
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switch(instr.execN)
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{
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case VM_EXEC_X:
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/* Don't modify execution. */
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break;
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case VM_EXEC_0:
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if((process->flags & VM_FLAG_N) != 0)
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exec = 0;
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break;
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case VM_EXEC_1:
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if((process->flags & VM_FLAG_N) == 0)
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exec = 0;
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break;
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default:
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vm_assert(0, "Invalid instruction: execN undefined.");
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break;
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}
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// Only do further instruction execution when
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// the execution condition is met.
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if(exec)
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{
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CommandInfo info = { 0 };
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switch(instr.input0)
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{
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case VM_INPUT_ZERO: info.input0 = 0; break;
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case VM_INPUT_POP: info.input0 = vm_pop(process); break;
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case VM_INPUT_PEEK: info.input0 = vm_peek(process); break;
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case VM_INPUT_ARG: info.input0 = instr.argument; break;
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default: vm_assert(0, "Invalid instruction: input0 undefined.");
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}
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switch(instr.input1)
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{
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case VM_INPUT_ZERO: info.input1 = 0; break;
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case VM_INPUT_POP: info.input1 = vm_pop(process); break;
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default: vm_assert(0, "Invalid instruction: input1 undefined.");
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}
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info.argument = instr.argument;
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info.additional = instr.cmdinfo;
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switch(instr.command)
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{
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case VM_CMD_COPY: cmd_copy(&info); break;
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case VM_CMD_STORE: cmd_store(process, &info); break;
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case VM_CMD_LOAD: cmd_load(process, &info); break;
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case VM_CMD_MATH: cmd_math(&info); break;
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case VM_CMD_SYSCALL: vm_syscall(process, &info); break;
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case VM_CMD_HWIO: vm_hwio(process, &info); break;
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case VM_CMD_SPGET: cmd_spget(process, &info); break;
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case VM_CMD_SPSET: cmd_spset(process, &info); break;
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case VM_CMD_BPGET: cmd_bpget(process, &info); break;
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case VM_CMD_BPSET: cmd_bpset(process, &info); break;
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case VM_CMD_CPGET: cmd_cpget(process, &info); break;
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case VM_CMD_GET: cmd_get(process, &info); break;
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case VM_CMD_SET: cmd_set(process, &info); break;
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default: vm_assert(0, "Invalid instruction: command undefined.");
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}
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switch(instr.flags)
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{
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case VM_FLAG_YES:
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process->flags = 0;
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if(info.output == 0)
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process->flags |= VM_FLAG_Z;
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else if((info.output & (1<<31)) != 0)
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process->flags |= VM_FLAG_N;
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break;
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case VM_FLAG_NO: break;
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default:
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vm_assert(0, "Invalid instruction: invalid flags.");
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}
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switch(instr.output)
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{
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case VM_OUTPUT_DISCARD: break;
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case VM_OUTPUT_PUSH: vm_push(process, info.output); break;
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case VM_OUTPUT_JUMP: process->codePointer = info.output; break;
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default:
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vm_assert(0, "Invalid instruction: invalid output.");
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}
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}
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return process->codePointer < process->module->length;
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}
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void vm_push(Process *process, uint32_t value)
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{
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vm_assert(process != NULL, "process must not be NULL.");
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vm_assert(process->stackPointer < VM_STACKSIZE, "Stack overflow");
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process->stack[++process->stackPointer] = value;
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}
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uint32_t vm_pop(Process *process)
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{
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vm_assert(process != NULL, "process must not be NULL.");
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uint32_t psp = process->stackPointer;
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uint32_t val = process->stack[process->stackPointer--];
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// Underflow check works because unsigned overflow is defined ;)
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vm_assert(psp >= process->stackPointer, "Stack underflow");
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return val;
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}
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uint32_t vm_peek(Process *process)
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{
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vm_assert(process != NULL, "process must not be NULL.");
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return process->stack[process->stackPointer];
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}
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uint8_t vm_read_byte(Process *process, uint32_t address)
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{
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vm_assert(process != NULL, "process must not be NULL.");
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uint32_t page = address / process->mmap.pageSize;
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uint32_t index = address % process->mmap.pageSize;
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vm_assert(page < process->mmap.length, "Out of memory.");
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return process->mmap.pages[page][index];
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}
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void vm_write_byte(Process *process, uint32_t address, uint8_t value)
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{
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vm_assert(process != NULL, "process must not be NULL.");
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uint32_t page = address / process->mmap.pageSize;
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uint32_t index = address % process->mmap.pageSize;
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vm_assert(page < process->mmap.length, "Out of memory.");
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process->mmap.pages[page][index] = value;
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} |