day1 week1

week1/day1/README.md

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+# Day 1: Variables, Memory, and the Stack
+
+## 📝 Concepts Covered
+Today we explored how high-level C variables are translated into low-level machine instructions and memory operations.
+
+### 1. The Stack and RBP
+Local variables in C are stored on the **Stack**. The CPU uses the `RBP` (Base Pointer) register as a reference point to find these variables.
+- `int a = 123;` -> `mov DWORD PTR [rbp-4], 0x7b`
+
+### 2. Register Basics (x64)
+Registers are small, fast storage locations inside the CPU.
+- `RAX`, `RBX`, `RCX`, `RDX`: General purpose 64-bit registers.
+- `EAX`, `EBX`, `ECX`, `EDX`: The lower 32-bit halves of the above (used for `int` in C).
+
+### 3. Data Sizes
+The assembly instruction specifies how much data to move:
+- `BYTE PTR`: 1 byte (`char`)
+- `WORD PTR`: 2 bytes (`short`)
+- `DWORD PTR`: 4 bytes (`int`)
+- `QWORD PTR`: 8 bytes (`long` or pointers)
+
+### 4. Arithmetic Pattern
+CPUs perform arithmetic using a **Load-Modify-Store** cycle:
+1. **Load** memory value into a register.
+2. **Add/Sub** the register value.
+3. **Store** the register result back into memory.
+
+## 🛠 Exercises Completed
+- `exo_1.c`: Basic assignment and hex identification.
+- `exo_2.c`: Arithmetic deconstruction (The `add` instruction).
+- `exo_3.c`: Data type sizes and memory offsets.

week1/day1/anki_cards.md

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+# Day 1: C & Reverse Engineering Anki Cards
+
+## Card 1
+**Front:** In x64 Assembly, what does `DWORD PTR` indicate about the size of the data?
+**Back:** It indicates a 32-bit (4-byte) value, typically used for an `int` in C.
+
+## Card 2
+**Front:** Translate the C code `int x = 10;` into a conceptual x64 assembly instruction.
+**Back:** `mov DWORD PTR [rbp-offset], 0xa`
+
+## Card 3
+**Front:** Why can't a CPU usually add two memory locations directly (e.g., `add [mem1], [mem2]`)?
+**Back:** Architecture constraints. It must follow the **Load-Modify-Store** pattern: move values into registers, perform the addition, and store the result back.
+
+## Card 4
+**Front:** What is the relationship between `RAX` and `EAX`?
+**Back:** `EAX` is the lower 32-bit half of the 64-bit `RAX` register.
+
+## Card 5
+**Front:** Match the C type to its Assembly size prefix:
+1. `char`
+2. `short`
+3. `int`
+**Back:** 
+1. `BYTE PTR` (1 byte)
+2. `WORD PTR` (2 bytes)
+3. `DWORD PTR` (4 bytes)
+
+## Card 6
+**Front:** What does the `RBP` register represent in the context of local variables?
+**Back:** The **Base Pointer**. It serves as a fixed reference point on the stack from which local variables are accessed via offsets (e.g., `[rbp-4]`).

week1/day1/exo_1.c

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+#include <stdio.h>
+
+int main(){
+    int a = 123;
+    int b = 456;
+    return 0;
+}

week1/day1/exo_2.c

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+
+int main(){
+    int a = 10;
+    int b = 20;
+    int sum = a + b;
+    return 0;
+}

week1/day1/exo_3.c

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+int main(){
+    char a = 1;
+    short b = 22;
+    int c = 123;
+    return 0;
+}