From fffad9aea3594c7de6ba918058c1e033c725a274 Mon Sep 17 00:00:00 2001
From: Aryadev Chavali <aryadev@aryadevchavali.com>
Date: Sun, 22 Oct 2023 20:40:42 +0100
Subject: Added and implemented OP_JUMP_ABS

Jumps to the operand given, interpreted as a word, an absolute
address.
---
 src/inst.c    | 21 +++++++++++++--------
 src/inst.h    |  7 +++++++
 src/runtime.c |  7 ++++++-
 3 files changed, 26 insertions(+), 9 deletions(-)

(limited to 'src')

diff --git a/src/inst.c b/src/inst.c
index 9ca20bd..0428979 100644
--- a/src/inst.c
+++ b/src/inst.c
@@ -114,6 +114,10 @@ const char *opcode_as_cstr(opcode_t code)
   case OP_EQ_WORD:
     return "EQ_WORD";
     break;
+  case OP_JUMP_ABS:
+    return "JUMP_ABS";
+    break;
+    break;
   case OP_HALT:
     return "HALT";
     break;
@@ -205,7 +209,7 @@ void inst_print(inst_t instruction, FILE *fp)
 
 size_t inst_bytecode_size(inst_t inst)
 {
-  static_assert(NUMBER_OF_OPCODES == 31, "inst_bytecode_size: Out of date");
+  static_assert(NUMBER_OF_OPCODES == 32, "inst_bytecode_size: Out of date");
   size_t size = 1; // for opcode
   if (OPCODE_IS_TYPE(inst.opcode, OP_PUSH))
   {
@@ -220,15 +224,16 @@ size_t inst_bytecode_size(inst_t inst)
            OPCODE_IS_TYPE(inst.opcode, OP_MOV))
     // Only need a byte for the register
     ++size;
-  else if (OPCODE_IS_TYPE(inst.opcode, OP_POP))
-  // No operand or register so leave as is
-  {}
+  else if (OPCODE_IS_TYPE(inst.opcode, OP_DUP))
+    size += WORD_SIZE;
+  else if (inst.opcode == OP_JUMP_ABS)
+    size += WORD_SIZE;
   return size;
 }
 
 void inst_write_bytecode(inst_t inst, darr_t *darr)
 {
-  static_assert(NUMBER_OF_OPCODES == 31, "inst_write_bytecode: Out of date");
+  static_assert(NUMBER_OF_OPCODES == 32, "inst_write_bytecode: Out of date");
   // Append opcode
   darr_append_byte(darr, inst.opcode);
   // Then append 0 or more operands
@@ -238,7 +243,7 @@ void inst_write_bytecode(inst_t inst, darr_t *darr)
   else if (OPCODE_IS_TYPE(inst.opcode, OP_PUSH_REGISTER) ||
            OPCODE_IS_TYPE(inst.opcode, OP_MOV))
     to_append = DATA_TYPE_BYTE;
-  else if (OPCODE_IS_TYPE(inst.opcode, OP_DUP))
+  else if (OPCODE_IS_TYPE(inst.opcode, OP_DUP) || inst.opcode == OP_JUMP)
     to_append = DATA_TYPE_WORD;
 
   switch (to_append)
@@ -300,7 +305,7 @@ data_t read_type_from_darr(darr_t *darr, data_type_t type)
 
 inst_t inst_read_bytecode(darr_t *darr)
 {
-  static_assert(NUMBER_OF_OPCODES == 31, "inst_read_bytecode: Out of date");
+  static_assert(NUMBER_OF_OPCODES == 32, "inst_read_bytecode: Out of date");
   if (darr->used >= darr->available)
     return (inst_t){0};
   inst_t inst     = {0};
@@ -315,7 +320,7 @@ inst_t inst_read_bytecode(darr_t *darr)
   else if (OPCODE_IS_TYPE(opcode, OP_PUSH_REGISTER) ||
            OPCODE_IS_TYPE(opcode, OP_MOV))
     inst.operand = read_type_from_darr(darr, DATA_TYPE_BYTE);
-  else if (OPCODE_IS_TYPE(opcode, OP_DUP))
+  else if (OPCODE_IS_TYPE(opcode, OP_DUP) || opcode == OP_JUMP_ABS)
     inst.operand = read_type_from_darr(darr, DATA_TYPE_WORD);
   // Otherwise opcode doesn't take operands
 
diff --git a/src/inst.h b/src/inst.h
index 61d7ede..a9709fd 100644
--- a/src/inst.h
+++ b/src/inst.h
@@ -65,6 +65,10 @@ typedef enum
   OP_EQ_HWORD,
   OP_EQ_WORD,
 
+  // Mathematical operations
+  // Program control flow
+  OP_JUMP_ABS,
+
   // Should not be an opcode
   NUMBER_OF_OPCODES,
   OP_HALT = 0b11111111, // top of the byte is a HALT
@@ -123,4 +127,7 @@ inst_t *insts_read_bytecode_file(FILE *, size_t *);
 #define INST_XOR(TYPE) ((inst_t){.opcode = OP_XOR_##TYPE})
 #define INST_EQ(TYPE)  ((inst_t){.opcode = OP_EQ_##TYPE})
 
+#define INST_JUMP_ABS(OP) \
+  ((inst_t){.opcode = OP_JUMP_ABS, .operand = DWORD(OP)})
+
 #endif
diff --git a/src/runtime.c b/src/runtime.c
index c2c793c..5b6c547 100644
--- a/src/runtime.c
+++ b/src/runtime.c
@@ -19,7 +19,7 @@
 
 void vm_execute(vm_t *vm)
 {
-  static_assert(NUMBER_OF_OPCODES == 31, "vm_execute: Out of date");
+  static_assert(NUMBER_OF_OPCODES == 32, "vm_execute: Out of date");
   struct Program *prog = &vm->program;
   if (prog->ptr >= prog->max)
     // TODO: Error (Went past end of program)
@@ -110,6 +110,11 @@ void vm_execute(vm_t *vm)
         vm_peek(vm, OPCODE_DATA_TYPE(instruction.opcode, OP_EQ)).as_word;
     prog->ptr++;
   }
+  else if (instruction.opcode == OP_JUMP_ABS)
+  {
+    // Set prog->ptr to the jump point requested
+    prog->ptr = instruction.operand.as_word;
+  }
   else if (instruction.opcode == OP_HALT)
   {
     // Do nothing here.  Should be caught by callers of vm_execute
-- 
cgit v1.2.3-13-gbd6f