Initial Commit

1 files changed, 369 insertions, 0 deletions

diff --git a/wai.c b/wai.c
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index 0000000..7db4806
--- /dev/null
+++ b/wai.c
@@ -0,0 +1,369 @@
+/*
+ * SPDX-FileCopyrightText: 2025 orangerot <me@orangerot.dev>
+ *
+ * SPDX-License-Identifier: GPL-3.0
+ *
+ * This program, named WAI, is a WebAssembly Interpreter. 
+ * Compile using make. 
+ * Usage: wai [FILE.wasm]
+ *
+ * Copyright (C) 2025  orangrot <me@orangerot.dev>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <endian.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+
+enum section {
+  Section_Custom,
+  Section_Type,
+  Section_Import,
+  Section_Function,
+  Section_Table,
+  Section_Memory,
+  Section_Global,
+  Section_Export,
+  Section_Start,
+  Section_Element,
+  Section_Code,
+  Section_Data,
+  Section_Data_Count,
+};
+
+#define STACK_CAPACITY 1024
+struct stack {
+  double items[STACK_CAPACITY];
+  size_t count;
+};
+
+
+struct module {
+  struct type_t *types;
+  char *funcs[128];
+  struct table_t *tables;
+  struct mem_t *mems;
+  struct global_t *globals;
+  struct elem_t *elems;
+  struct data_t *datas;
+  struct start_t *start;
+  struct import_t *imports;
+  struct export_t *exports;
+  char *binary;
+  struct stack stack;
+  int scope;
+};
+
+enum INSTRUCTION {
+  INSTR_CALL = 0x10,
+  INSTR_ELSE = 0x05,
+  INSTR_END = 0x0b,
+  INSTR_F64 = 0x7C,
+  INSTR_F64_CONST = 0x44,
+  INSTR_F64_LT = 0x63,
+  INSTR_F64_MUL = 0xa2,
+  INSTR_F64_SUB = 0xa1,
+  INSTR_IF = 0x04,
+  INSTR_LOCAL_GET = 0x20,
+};  
+
+enum TYPE {
+  TYPE_I32 = 0x7F,
+  TYPE_I64 = 0x7E,
+  TYPE_F32 = 0x7D,
+  TYPE_F64 = 0x7C,
+  TYPE_V128= 0x7B,
+  TYPE_FUNCREF = 0x70,
+  TYPE_EXTERNREF = 0x6F
+};
+
+#define incr(i, len) i++; if (i >= len) {return -1;}
+
+void stack_push(struct stack *s, double a) {
+  s->items[s->count++] = a;
+  printf("stack: ");
+  for (int i = 0; i < s->count; i++) {
+   printf("%f, ", s->items[i]);
+  }
+  printf("\n");
+} 
+
+double stack_pop(struct stack *s) {
+  s->count--;
+  return s->items[s->count];
+}
+
+double stack_top(struct stack *s) {
+  return s->items[s->count-1];
+} 
+
+int parse_type(char *binary, int len) {
+  int i = 0;
+  enum TYPE param = binary[i];
+  printf("type %x\n", param);
+  incr(i, len);
+  switch (param) {
+    case TYPE_I32:
+    case TYPE_I64:
+    case TYPE_F32:
+    case TYPE_F64:
+    case TYPE_V128:
+    case TYPE_FUNCREF:
+    case TYPE_EXTERNREF:
+      break;
+    default:
+      return -1;
+  }
+  return i;
+}
+
+int parse_function(struct module *module, char *binary, double param, int len);
+int parse_instruction(struct module *module, char *binary, double param, int len) {
+  int i = 0;
+  enum INSTRUCTION instr = (u_char) binary[i];
+  char *instr_addr = &binary[i];
+  incr(i, len);
+
+  switch (instr) {
+    case INSTR_CALL:
+      int a = binary[i];
+      incr(i, len);
+      parse_function(module, module->funcs[a], stack_pop(&module->stack), len);
+      break;
+    case INSTR_ELSE:
+      printf("reached else instruction: impossible!\n");
+    case INSTR_END:
+      break;
+    case INSTR_F64:
+      break;
+    case INSTR_F64_CONST:
+      double k = *(double*)&binary[i];
+      stack_push(&module->stack, k);
+      i += 8;
+      break;
+    case INSTR_F64_LT: {
+      double b = stack_pop(&module->stack);
+      double a = stack_pop(&module->stack);
+      stack_push(&module->stack, a < b);
+      break;
+       }
+    case INSTR_F64_MUL: {
+      double b = stack_pop(&module->stack);
+      double a = stack_pop(&module->stack);
+      stack_push(&module->stack, a * b);
+      break;
+      }
+    case INSTR_F64_SUB: {
+      double b = stack_pop(&module->stack);
+      double a = stack_pop(&module->stack);
+      stack_push(&module->stack, a - b);
+      break;
+      }
+    case INSTR_IF: {
+      double a = stack_pop(&module->stack);
+      while (binary[i] != INSTR_ELSE) {
+        if (a) {
+          i += parse_instruction(module, &binary[i], param, len);
+        } else {
+          incr(i, len);
+        }
+      } 
+      incr(i, len);
+      while (binary[i] != INSTR_END) {
+        if (a) {
+          incr(i, len);
+        } else {
+          i += parse_instruction(module, &binary[i], param, len);
+        }
+      }
+      incr(i, len);
+      break;
+      }
+    case INSTR_LOCAL_GET:
+      int local_index = binary[i];
+      incr(i, len);
+      stack_push(&module->stack, param);
+      break;
+    default:
+      printf("unknown instruction! %x at %lx\n", instr, instr_addr - module->binary);
+      exit(1);
+  }
+  return i;
+}
+
+int parse_function(struct module *module, char *binary, double param, int len) {
+  int i = 0;
+  int body_size = binary[i];
+  incr(i, len);
+  // int local_decl_cound = binary[i];
+  incr(i, len);
+  module->scope = 1;
+  while (binary[i] != INSTR_END) {
+    i += parse_instruction(module, &binary[i], param, len);
+  }
+  incr(i, len);
+  return i;
+}
+
+int parse_section(struct module *module, char *binary, int len) {
+  int i = 0;
+  enum section type = binary[i];
+  incr(i, len);
+  int size = binary[i];
+  incr(i, len);
+  printf("section %x with size %d\n", type, size);
+
+  switch ((enum section) type) {
+    case Section_Custom:
+      break;
+    case Section_Type: 
+        printf("section: type\n");
+        int num_types = binary[i];
+        incr(i, len);
+        for (int type_i = 0; type_i < num_types; type_i++) {
+          if (binary[i] != 0x60) {
+            printf("expected function type, found %x\n", binary[i]);
+            return -1;
+          }
+          incr(i, len);
+          int num_params = binary[i];
+          incr(i, len);
+          for (int params_i = 0; params_i < num_params; params_i++) {
+            i += (parse_type(&binary[i], len));
+          }
+          int num_results = binary[i];
+          incr(i, len);
+          for (int results_i = 0; results_i < num_results; results_i++) {
+            i += (parse_type(&binary[i], len));
+          }
+        }
+        break;
+    case Section_Import:
+      break;
+    case Section_Function:
+      printf("section: function\n");
+      int num_functions = binary[i];
+      incr(i, len);
+      for (int function_i = 0; function_i < num_functions; function_i++) {
+        incr(i, len);
+      }
+      break;
+    case Section_Table:
+      break;
+    case Section_Memory:
+      break;
+    case Section_Global:
+      break;
+    case Section_Export:
+      printf("section: exports\n");
+      int num_exports = binary[i];
+      incr(i, len);
+      for (int exports_i = 0; exports_i < num_exports; exports_i++) {
+        int string_len = binary[i];
+        incr(i, len);
+        printf("export name: ");
+        for (int si = 0; si < string_len; si++) {
+          putchar(binary[i]);
+          incr(i, len);
+        }
+        putchar('\n');
+        // export kind
+        incr(i, len);
+        // export func index
+        incr(i, len);
+      }
+      break;
+    case Section_Start:
+      break;
+    case Section_Element:
+      break;
+    case Section_Code:
+      printf("section: code\n");
+      int num_functions2 = binary[i];
+      incr(i, len);
+      for (int function_i = 0; function_i < num_functions2; function_i++) {
+        module->funcs[function_i] = &binary[i];
+        i += parse_function(module, &binary[i], 4, len);
+      }
+      printf("result: %f\n", module->stack.items[0]);
+      break;
+    case Section_Data:
+      break;
+    case Section_Data_Count:
+      break;
+    default:
+      fprintf(stderr, "expectet section\n");
+      exit(1);
+  }
+
+  if (size == 0x0) {incr(i, len);}
+  return i;
+}
+
+int parse_module(char *binary, size_t len) {
+  int i = 0;
+  char *magic = "\0asm";
+  while (i < 4) {
+    if (binary[i] != magic[i]) {
+      fprintf(stderr, "no wasm magic\n");
+      return 0;
+    }
+    incr(i, len);
+  }
+  printf("magic found\n");
+  printf("wasm version: %d\n", le32toh(*(int*)&binary[i]));
+  i += 4;
+  printf("addr %d\n", i);
+
+  struct module module = {0};
+  module.binary = binary;
+
+  while (i < len) {
+    i += parse_section(&module, &binary[i], len);
+  }
+  return i;
+}
+
+
+int main(int argc, char **argv) {
+  
+  if (argc != 2) {
+    fprintf(stderr, "Usage: %s [file]\n", argv[0]);
+    return 1;
+  };
+  FILE *file = fopen(argv[1], "r");
+  if (file == NULL) {
+    fprintf(stderr, "Failed to open file\n");
+    fclose(file);
+    return 1;
+  }
+  struct stat st;
+  stat(argv[1], &st);
+  printf("size: %ld\n", st.st_size);
+  
+  char *binary = malloc(st.st_size);
+  fread(binary, st.st_size, st.st_size, file);
+
+  if (parse_module(binary, st.st_size) == -1) {
+    printf("error :(\n");
+  }
+  
+  free(binary);
+  fclose(file);
+  return 0;
+}
+