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.