From 073a23152e509d42ce256f635fbb3da99e0d176a Mon Sep 17 00:00:00 2001
From: Aryadev Chavali <aryadev@aryadevchavali.com>
Date: Sun, 22 Oct 2023 20:29:02 +0100
Subject: Use conversion functions for (h)word to and from bytes instead of bit
shifting
Wasn't very secure for endianness, and using these helpers abstracts
the details away a bit in case I want to enforce a certain system.
---
src/runtime.c | 55 +++++++++++++++++++++++++++++--------------------------
src/runtime.h | 7 ++++---
2 files changed, 33 insertions(+), 29 deletions(-)
(limited to 'src')
diff --git a/src/runtime.c b/src/runtime.c
index 5c9b985..a5ffd09 100644
--- a/src/runtime.c
+++ b/src/runtime.c
@@ -63,7 +63,7 @@ void vm_execute(vm_t *vm)
else if (OPCODE_IS_TYPE(instruction.opcode, OP_MOV))
{
data_t d =
- MOV_ROUTINES[instruction.opcode](vm, instruction.operand.as_word);
+ MOV_ROUTINES[instruction.opcode](vm, instruction.operand.as_byte);
vm->registers.ret = d.as_word;
prog->ptr++;
}
@@ -274,30 +274,32 @@ data_t vm_peek(vm_t *vm, data_type_t type)
return DBYTE(0);
return DBYTE(vm->stack.data[vm->stack.ptr - 1]);
break;
- case DATA_TYPE_HWORD:
+ case DATA_TYPE_HWORD: {
if (vm->stack.ptr < HWORD_SIZE)
// TODO: Error STACK_UNDERFLOW
return DHWORD(0);
- hword h = 0;
+ byte bytes[HWORD_SIZE] = {0};
for (size_t i = 0; i < HWORD_SIZE; ++i)
{
- byte b = vm->stack.data[vm->stack.ptr - 1 - i];
- h = h | (((word)b) << (i * 8));
+ byte b = vm->stack.data[vm->stack.ptr - i - 1];
+ bytes[HWORD_SIZE - 1 - i] = b;
}
- return DWORD(h);
+ return DWORD(convert_bytes_to_hword(bytes));
break;
- case DATA_TYPE_WORD:
+ }
+ case DATA_TYPE_WORD: {
if (vm->stack.ptr < WORD_SIZE)
// TODO: Error STACK_UNDERFLOW
return DWORD(0);
- word w = 0;
+ byte bytes[WORD_SIZE] = {0};
for (size_t i = 0; i < WORD_SIZE; ++i)
{
- byte b = vm->stack.data[vm->stack.ptr - 1 - i];
- w = w | (((word)b) << (i * 8));
+ byte b = vm->stack.data[vm->stack.ptr - i - 1];
+ bytes[WORD_SIZE - 1 - i] = b;
}
- return DWORD(w);
+ return DWORD(convert_bytes_to_hword(bytes));
break;
+ }
default:
return DBYTE(0);
break;
@@ -317,10 +319,11 @@ void vm_push_hword(vm_t *vm, data_t f)
if (vm->stack.ptr + HWORD_SIZE >= vm->stack.max)
// TODO: Error STACK_OVERFLOW
return;
- for (size_t i = 32; i > 0; i -= 8)
+ byte bytes[HWORD_SIZE] = {0};
+ convert_hword_to_bytes(f.as_hword, bytes);
+ for (size_t i = 0; i < HWORD_SIZE; ++i)
{
- const word mask = ((word)0b11111111) << (i - 8);
- byte b = (f.as_hword & mask) >> (i - 8);
+ byte b = bytes[HWORD_SIZE - i - 1];
vm_push_byte(vm, DBYTE(b));
}
}
@@ -330,11 +333,11 @@ void vm_push_word(vm_t *vm, data_t w)
if (vm->stack.ptr + WORD_SIZE >= vm->stack.max)
// TODO: Error STACK_OVERFLOW
return;
- // By default store in big endian
- for (size_t i = 64; i > 0; i -= 8)
+ byte bytes[WORD_SIZE] = {0};
+ convert_word_to_bytes(w.as_word, bytes);
+ for (size_t i = 0; i < WORD_SIZE; ++i)
{
- const word mask = ((word)0b11111111) << (i - 8);
- byte b = (w.as_word & mask) >> (i - 8);
+ byte b = bytes[WORD_SIZE - i - 1];
vm_push_byte(vm, DBYTE(b));
}
}
@@ -436,13 +439,13 @@ data_t vm_pop_hword(vm_t *vm)
if (vm->stack.ptr < HWORD_SIZE)
// TODO: Error STACK_UNDERFLOW
return DHWORD(0);
- hword h = 0;
+ byte bytes[HWORD_SIZE] = {0};
for (size_t i = 0; i < HWORD_SIZE; ++i)
{
- data_t b = vm_pop_byte(vm);
- h = h | ((word)(b.as_byte) << (i * 8));
+ data_t b = vm_pop_byte(vm);
+ bytes[HWORD_SIZE - 1 - i] = b.as_byte;
}
- return DWORD(h);
+ return DWORD(convert_bytes_to_hword(bytes));
}
data_t vm_pop_word(vm_t *vm)
@@ -450,13 +453,13 @@ data_t vm_pop_word(vm_t *vm)
if (vm->stack.ptr < WORD_SIZE)
// TODO: Error STACK_UNDERFLOW
return DWORD(0);
- word w = 0;
+ byte bytes[WORD_SIZE] = {0};
for (size_t i = 0; i < WORD_SIZE; ++i)
{
- data_t b = vm_pop_byte(vm);
- w = w | ((word)(b.as_byte) << (i * 8));
+ data_t b = vm_pop_byte(vm);
+ bytes[WORD_SIZE - 1 - i] = b.as_byte;
}
- return DWORD(w);
+ return DWORD(convert_bytes_to_word(bytes));
}
void vm_not_byte(vm_t *vm)
diff --git a/src/runtime.h b/src/runtime.h
index 3e4c295..5ee5f9b 100644
--- a/src/runtime.h
+++ b/src/runtime.h
@@ -83,6 +83,10 @@ static const push_reg_f PUSH_REG_ROUTINES[] = {
[OP_PUSH_REGISTER_WORD] = vm_push_word_register,
};
+data_t vm_pop_byte(vm_t *);
+data_t vm_pop_hword(vm_t *);
+data_t vm_pop_word(vm_t *);
+
data_t vm_mov_byte(vm_t *, byte);
data_t vm_mov_hword(vm_t *, byte);
data_t vm_mov_word(vm_t *, byte);
@@ -94,9 +98,6 @@ static const mov_f MOV_ROUTINES[] = {
[OP_MOV_WORD] = vm_mov_word,
};
-data_t vm_pop_byte(vm_t *);
-data_t vm_pop_hword(vm_t *);
-data_t vm_pop_word(vm_t *);
void vm_not_byte(vm_t *);
void vm_not_hword(vm_t *);
--
cgit v1.2.3-13-gbd6f