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Add comprehensive C learning materials with specialized topic tutorials
Complete learning guide covering ALL C concepts from beginner to advanced: Main Guide (LEARNING_C_WITH_CLAY.md): - Added Chapters 3-5: Operators, Control Flow, Loops - Enhanced Chapters 6-13: Functions, Pointers, Structs, Arrays, Strings, Type Casting, Storage Classes, Recursion - All chapters include extensive Clay library examples - Progressive difficulty from basics to advanced topics Specialized Tutorial Files (docs/): - 14_bit_manipulation.md: Comprehensive bit operations guide * Bitwise operators, masks, flags * Counting bits, power of 2 operations * Practical applications with Clay examples - 21_standard_library.md: C Standard Library overview * stdio.h, stdlib.h, string.h, math.h * Clay's zero-dependency approach * Custom implementations vs stdlib - 22_file_io.md: Complete File I/O guide * Text and binary file operations * Configuration files for Clay apps * Error handling and best practices - 23_command_line_arguments.md: CLI argument parsing * argc/argv basics * Flag parsing and subcommands * Clay application configuration examples - README_C_TUTORIALS.md: Master index and learning guide * Complete chapter overview * Learning path recommendations * Progress tracking checklist * Prerequisites and setup instructions Features: - 24 comprehensive chapters covering all C concepts - 100+ code examples with detailed explanations - Real-world patterns from Clay library throughout - Practice exercises for each chapter - Modular organization for easy navigation - Zero-dependency programming concepts - Professional C development practices Total content: ~70,000+ words of detailed tutorials
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docs/14_bit_manipulation.md
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# Chapter 14: Bit Manipulation in C
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## Complete Guide with Clay Library Examples
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---
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## 14.1 Binary Number System
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Understanding binary is essential for bit manipulation:
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```c
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// Decimal vs Binary
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0 = 0000
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1 = 0001
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2 = 0010
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3 = 0011
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4 = 0100
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5 = 0101
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6 = 0110
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7 = 0111
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8 = 1000
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```
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### Converting Binary to Decimal
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```c
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#include <stdio.h>
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int binaryToDecimal(int binary) {
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int decimal = 0, base = 1;
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while (binary > 0) {
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int lastDigit = binary % 10;
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decimal += lastDigit * base;
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base *= 2;
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binary /= 10;
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}
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return decimal;
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}
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int main(void) {
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printf("%d\n", binaryToDecimal(1010)); // 10
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printf("%d\n", binaryToDecimal(1111)); // 15
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return 0;
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}
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```
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---
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## 14.2 Bitwise Operators
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### AND Operator (&)
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```c
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// Both bits must be 1
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int a = 5; // 0101
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int b = 3; // 0011
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int c = a & b; // 0001 = 1
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// Check if number is even
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int isEven(int n) {
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return (n & 1) == 0; // Check if last bit is 0
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}
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```
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**Clay Example:**
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```c
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// Check if corner radius flag is set
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typedef enum {
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CLAY_CORNER_RADIUS_TOP_LEFT = 1 << 0, // 0001
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CLAY_CORNER_RADIUS_TOP_RIGHT = 1 << 1, // 0010
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CLAY_CORNER_RADIUS_BOTTOM_LEFT = 1 << 2, // 0100
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CLAY_CORNER_RADIUS_BOTTOM_RIGHT = 1 << 3 // 1000
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} Clay_CornerRadiusSet;
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// Check if top-left corner has radius
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if (flags & CLAY_CORNER_RADIUS_TOP_LEFT) {
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// Top left corner has radius
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}
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```
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### OR Operator (|)
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```c
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// At least one bit must be 1
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int a = 5; // 0101
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int b = 3; // 0011
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int c = a | b; // 0111 = 7
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// Set specific bit
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int setBit(int num, int pos) {
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return num | (1 << pos);
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}
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```
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**Clay Example:**
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```c
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// Combine multiple corner radius flags
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int flags = CLAY_CORNER_RADIUS_TOP_LEFT |
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CLAY_CORNER_RADIUS_TOP_RIGHT; // 0011 = both top corners
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// Add another flag
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flags |= CLAY_CORNER_RADIUS_BOTTOM_LEFT; // Now 0111 = three corners
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```
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### XOR Operator (^)
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```c
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// Bits must be different
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int a = 5; // 0101
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int b = 3; // 0011
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int c = a ^ b; // 0110 = 6
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// Swap two numbers without temp variable
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void swap(int *a, int *b) {
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*a = *a ^ *b;
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*b = *a ^ *b;
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*a = *a ^ *b;
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}
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```
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### NOT Operator (~)
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```c
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// Inverts all bits
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int a = 5; // 00000101
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int b = ~a; // 11111010 (in 8-bit)
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// Clear specific bit
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int clearBit(int num, int pos) {
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return num & ~(1 << pos);
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}
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```
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### Left Shift (<<)
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```c
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// Multiply by 2^n
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int a = 5; // 0101
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int b = a << 1; // 1010 = 10 (multiply by 2)
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int c = a << 2; // 10100 = 20 (multiply by 4)
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// Fast power of 2
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int powerOf2(int n) {
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return 1 << n; // 2^n
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}
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```
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**Clay Example:**
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```c
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// Define bit flags with left shift
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typedef enum {
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CLAY_CORNER_RADIUS_TOP_LEFT = 1 << 0, // 1
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CLAY_CORNER_RADIUS_TOP_RIGHT = 1 << 1, // 2
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CLAY_CORNER_RADIUS_BOTTOM_LEFT = 1 << 2, // 4
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CLAY_CORNER_RADIUS_BOTTOM_RIGHT = 1 << 3 // 8
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} Clay_CornerRadiusSet;
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```
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### Right Shift (>>)
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```c
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// Divide by 2^n
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int a = 20; // 10100
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int b = a >> 1; // 01010 = 10 (divide by 2)
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int c = a >> 2; // 00101 = 5 (divide by 4)
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// Extract specific bits
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int getBits(int num, int start, int count) {
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return (num >> start) & ((1 << count) - 1);
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}
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```
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---
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## 14.3 Common Bit Operations
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### Check if Bit is Set
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```c
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int isBitSet(int num, int pos) {
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return (num & (1 << pos)) != 0;
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}
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int main(void) {
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int num = 5; // 0101
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printf("%d\n", isBitSet(num, 0)); // 1 (bit 0 is set)
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printf("%d\n", isBitSet(num, 1)); // 0 (bit 1 is not set)
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printf("%d\n", isBitSet(num, 2)); // 1 (bit 2 is set)
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return 0;
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}
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```
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### Set a Bit
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```c
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int setBit(int num, int pos) {
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return num | (1 << pos);
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}
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int main(void) {
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int num = 5; // 0101
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num = setBit(num, 1); // 0111 = 7
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printf("%d\n", num);
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return 0;
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}
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```
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### Clear a Bit
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```c
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int clearBit(int num, int pos) {
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return num & ~(1 << pos);
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}
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int main(void) {
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int num = 7; // 0111
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num = clearBit(num, 1); // 0101 = 5
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printf("%d\n", num);
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return 0;
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}
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```
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### Toggle a Bit
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```c
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int toggleBit(int num, int pos) {
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return num ^ (1 << pos);
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}
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int main(void) {
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int num = 5; // 0101
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num = toggleBit(num, 1); // 0111 = 7
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num = toggleBit(num, 1); // 0101 = 5 (back to original)
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printf("%d\n", num);
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return 0;
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}
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```
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---
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## 14.4 Bit Masks
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Masks select specific bits:
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```c
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// Extract RGB components from 32-bit color
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typedef struct {
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uint32_t color; // 0xAARRGGBB
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} Color;
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uint8_t getRed(Color c) {
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return (c.color >> 16) & 0xFF; // Mask: 0x00FF0000
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}
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uint8_t getGreen(Color c) {
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return (c.color >> 8) & 0xFF; // Mask: 0x0000FF00
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}
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uint8_t getBlue(Color c) {
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return c.color & 0xFF; // Mask: 0x000000FF
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}
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uint8_t getAlpha(Color c) {
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return (c.color >> 24) & 0xFF; // Mask: 0xFF000000
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}
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uint32_t makeColor(uint8_t r, uint8_t g, uint8_t b, uint8_t a) {
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return ((uint32_t)a << 24) |
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((uint32_t)r << 16) |
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((uint32_t)g << 8) |
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(uint32_t)b;
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}
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```
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**Clay Example (conceptual):**
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```c
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// Clay uses float colors, but shows similar concepts
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typedef struct {
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float r, g, b, a;
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} Clay_Color;
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// If Clay used packed colors:
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uint32_t packColor(Clay_Color c) {
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uint8_t r = (uint8_t)(c.r * 255);
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uint8_t g = (uint8_t)(c.g * 255);
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uint8_t b = (uint8_t)(c.b * 255);
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uint8_t a = (uint8_t)(c.a * 255);
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return (a << 24) | (r << 16) | (g << 8) | b;
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}
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```
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---
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## 14.5 Bit Fields in Structs
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Pack multiple values efficiently:
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```c
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struct Flags {
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unsigned int isVisible : 1; // 1 bit
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unsigned int isEnabled : 1; // 1 bit
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unsigned int priority : 3; // 3 bits (0-7)
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unsigned int id : 11; // 11 bits
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}; // Total: 16 bits = 2 bytes
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int main(void) {
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struct Flags f = {0};
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f.isVisible = 1;
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f.isEnabled = 1;
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f.priority = 5;
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f.id = 1024;
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printf("Size: %zu bytes\n", sizeof(f)); // 2 or 4 (compiler dependent)
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printf("Priority: %u\n", f.priority);
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return 0;
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}
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```
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**Clay Example (conceptual):**
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```c
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// Clay could use bit fields for layout flags
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typedef struct {
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uint32_t layoutDirection : 1; // 0 = horizontal, 1 = vertical
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uint32_t wrapChildren : 1; // Wrap to next line
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uint32_t alignmentX : 2; // 0-3 for alignment options
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uint32_t alignmentY : 2;
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uint32_t reserved : 26; // Future use
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} Clay_LayoutFlags;
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```
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---
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## 14.6 Counting Set Bits
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### Method 1: Loop
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```c
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int countSetBits(int n) {
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int count = 0;
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while (n > 0) {
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count += n & 1; // Add last bit
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n >>= 1; // Shift right
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}
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return count;
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}
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```
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### Method 2: Brian Kernighan's Algorithm
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```c
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int countSetBits(int n) {
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int count = 0;
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while (n > 0) {
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n &= (n - 1); // Clear rightmost set bit
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count++;
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}
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return count;
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}
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// Example: n = 12 (1100)
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// 1100 & 1011 = 1000 (count = 1)
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// 1000 & 0111 = 0000 (count = 2)
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```
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### Method 3: Lookup Table
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```c
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// Precomputed table for 4-bit numbers
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int table[16] = {
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0, 1, 1, 2, 1, 2, 2, 3,
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1, 2, 2, 3, 2, 3, 3, 4
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};
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int countSetBits(int n) {
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int count = 0;
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while (n > 0) {
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count += table[n & 0xF]; // Count 4 bits at a time
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n >>= 4;
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}
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return count;
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}
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```
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---
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## 14.7 Power of Two
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### Check if Power of 2
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```c
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int isPowerOfTwo(int n) {
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return n > 0 && (n & (n - 1)) == 0;
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}
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// Examples:
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// 4 (100) & 3 (011) = 0 → true
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// 5 (101) & 4 (100) = 4 → false
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// 8 (1000) & 7 (0111) = 0 → true
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```
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### Next Power of 2
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```c
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int nextPowerOfTwo(int n) {
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if (n <= 0) return 1;
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n--;
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n |= n >> 1;
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n |= n >> 2;
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n |= n >> 4;
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n |= n >> 8;
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n |= n >> 16;
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return n + 1;
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}
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int main(void) {
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printf("%d\n", nextPowerOfTwo(5)); // 8
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printf("%d\n", nextPowerOfTwo(17)); // 32
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return 0;
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}
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```
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---
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## 14.8 Swap Values
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### Without Temporary Variable
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```c
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void swap(int *a, int *b) {
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if (a != b) { // Must check for same address
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*a ^= *b;
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*b ^= *a;
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*a ^= *b;
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}
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}
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```
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### Swap Nibbles (4-bit)
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```c
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int swapNibbles(int n) {
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return ((n & 0x0F) << 4) | ((n & 0xF0) >> 4);
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}
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// Example: 0x5A → 0xA5
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```
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---
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## 14.9 Reverse Bits
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```c
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uint32_t reverseBits(uint32_t n) {
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uint32_t result = 0;
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for (int i = 0; i < 32; i++) {
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result <<= 1; // Shift result left
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result |= (n & 1); // Add rightmost bit of n
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n >>= 1; // Shift n right
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}
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return result;
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}
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```
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---
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## 14.10 Parity
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Check if number of set bits is even or odd:
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```c
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int getParity(int n) {
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int parity = 0;
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while (n > 0) {
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parity ^= (n & 1);
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n >>= 1;
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}
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return parity; // 0 = even, 1 = odd
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}
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```
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---
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## 14.11 Gray Code
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Convert between binary and Gray code:
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```c
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// Binary to Gray
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int binaryToGray(int n) {
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return n ^ (n >> 1);
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}
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|
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// Gray to Binary
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int grayToBinary(int n) {
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int binary = 0;
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while (n > 0) {
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binary ^= n;
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n >>= 1;
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}
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return binary;
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}
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```
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---
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## 14.12 Position of Rightmost Set Bit
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```c
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int rightmostSetBit(int n) {
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return n & ~(n - 1);
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}
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// Example: 12 (1100)
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// Returns: 4 (0100) - position of rightmost 1
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```
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|
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---
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## 14.13 Toggle All Bits After Rightmost Set Bit
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|
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```c
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int toggleAfterRightmost(int n) {
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return n ^ (n - 1);
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}
|
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|
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// Example: 12 (1100)
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// Returns: 15 (1111)
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||||
```
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|
||||
---
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|
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## 14.14 Extract and Set Bit Ranges
|
||||
|
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```c
|
||||
// Extract bits from position p to p+n
|
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int extractBits(int num, int p, int n) {
|
||||
return (num >> p) & ((1 << n) - 1);
|
||||
}
|
||||
|
||||
// Set bits from position p to p+n
|
||||
int setBits(int num, int p, int n, int value) {
|
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int mask = ((1 << n) - 1) << p;
|
||||
return (num & ~mask) | ((value << p) & mask);
|
||||
}
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 14.15 Practical Applications in Clay
|
||||
|
||||
### Bit Flags for UI State
|
||||
|
||||
```c
|
||||
typedef enum {
|
||||
CLAY_ELEMENT_VISIBLE = 1 << 0, // 0x01
|
||||
CLAY_ELEMENT_ENABLED = 1 << 1, // 0x02
|
||||
CLAY_ELEMENT_FOCUSED = 1 << 2, // 0x04
|
||||
CLAY_ELEMENT_HOVERED = 1 << 3, // 0x08
|
||||
CLAY_ELEMENT_PRESSED = 1 << 4, // 0x10
|
||||
CLAY_ELEMENT_SELECTED = 1 << 5, // 0x20
|
||||
CLAY_ELEMENT_DISABLED = 1 << 6, // 0x40
|
||||
CLAY_ELEMENT_HIDDEN = 1 << 7 // 0x80
|
||||
} Clay_ElementFlags;
|
||||
|
||||
typedef struct {
|
||||
uint32_t flags;
|
||||
} Clay_Element;
|
||||
|
||||
// Check state
|
||||
int isVisible(Clay_Element *el) {
|
||||
return (el->flags & CLAY_ELEMENT_VISIBLE) != 0;
|
||||
}
|
||||
|
||||
// Set state
|
||||
void setVisible(Clay_Element *el, int visible) {
|
||||
if (visible) {
|
||||
el->flags |= CLAY_ELEMENT_VISIBLE; // Set bit
|
||||
} else {
|
||||
el->flags &= ~CLAY_ELEMENT_VISIBLE; // Clear bit
|
||||
}
|
||||
}
|
||||
|
||||
// Toggle state
|
||||
void toggleVisible(Clay_Element *el) {
|
||||
el->flags ^= CLAY_ELEMENT_VISIBLE;
|
||||
}
|
||||
|
||||
// Multiple states at once
|
||||
void setInteractive(Clay_Element *el) {
|
||||
el->flags |= (CLAY_ELEMENT_VISIBLE |
|
||||
CLAY_ELEMENT_ENABLED);
|
||||
}
|
||||
```
|
||||
|
||||
### Optimized Hash Functions
|
||||
|
||||
```c
|
||||
// Clay uses hashing for element lookup
|
||||
uint32_t hashString(const char *str, size_t length) {
|
||||
uint32_t hash = 0;
|
||||
for (size_t i = 0; i < length; i++) {
|
||||
hash = (hash << 5) - hash + str[i]; // hash * 31 + c
|
||||
// Using bit shift instead of multiply
|
||||
}
|
||||
return hash;
|
||||
}
|
||||
```
|
||||
|
||||
### Memory Alignment
|
||||
|
||||
```c
|
||||
// Align size to power of 2
|
||||
size_t alignSize(size_t size, size_t alignment) {
|
||||
return (size + alignment - 1) & ~(alignment - 1);
|
||||
}
|
||||
|
||||
// Example: align to 16 bytes
|
||||
// size = 25
|
||||
// (25 + 15) & ~15 = 40 & 0xFFFFFFF0 = 32
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 14.16 Performance Tips
|
||||
|
||||
**Use bit operations for:**
|
||||
- ✅ Powers of 2 multiplication/division
|
||||
- ✅ Flag checks (faster than booleans)
|
||||
- ✅ Color packing/unpacking
|
||||
- ✅ Hash functions
|
||||
- ✅ Alignment calculations
|
||||
|
||||
**Avoid for:**
|
||||
- ❌ Regular arithmetic (compiler optimizes)
|
||||
- ❌ Readability-critical code
|
||||
- ❌ Floating-point operations
|
||||
|
||||
---
|
||||
|
||||
## 14.17 Key Concepts Learned
|
||||
- ✅ Bitwise operators: &, |, ^, ~, <<, >>
|
||||
- ✅ Bit manipulation: set, clear, toggle, check
|
||||
- ✅ Bit masks and extraction
|
||||
- ✅ Bit fields in structs
|
||||
- ✅ Counting set bits
|
||||
- ✅ Power of 2 operations
|
||||
- ✅ Practical applications in Clay
|
||||
- ✅ Performance considerations
|
||||
|
||||
---
|
||||
|
||||
## Practice Exercises
|
||||
|
||||
1. Write a function to count trailing zeros in a number
|
||||
2. Implement bitwise rotation (rotate left/right)
|
||||
3. Find the only non-duplicate number in an array (all others appear twice)
|
||||
4. Swap all odd and even bits in a number
|
||||
5. Add two numbers without using + operator
|
||||
6. Implement a bit vector data structure
|
||||
7. Create a compact permission system using bit flags
|
||||
8. Write efficient popcount for 64-bit numbers
|
||||
Loading…
Add table
Add a link
Reference in a new issue