Types Module - User Guide

What is Types?

• Types module defines fixed-width integer types for safety-critical systems.
• All framework code uses uint32_t, int16_t, etc. instead of bare int or
• long. This ensures consistent behavior across platforms (8-bit MCU, 32-bit ARM,
• 64-bit x86).
• Key principle: Platform-independent sizing guarantees.

Available Types

• * // Unsigned integers
  * uint8_t   uint16_t   uint32_t   uint64_t
  *
  * // Signed integers  
  * int8_t    int16_t    int32_t    int64_t
  *
  * // Boolean
  * bool      (C11 standard, true/false)
  *
  * // Standard types
  * size_t    (pointer-sized)
  * 

Quick Start

1. Include Header

• * #include "safeapi/types/sapi_types.h"
  * 

2. Use Fixed-Width Types

• * // BAD: Platform-dependent
  * int counter;          // Could be 16, 32, or 64 bits!
  * unsigned long value;  // Size varies
  *
  * // GOOD: Platform-independent
  * uint32_t counter;     // Always 32 bits
  * uint64_t value;       // Always 64 bits
  * 

Type Ranges

•  * uint8_t:   0 to 255
   * uint16_t:  0 to 65,535
   * uint32_t:  0 to 4,294,967,295
   * uint64_t:  0 to (2^64 - 1)
   *
   * int8_t:    -128 to 127
   * int16_t:   -32,768 to 32,767
   * int32_t:   -2,147,483,648 to 2,147,483,647
   * int64_t:   -(2^63) to +(2^63 - 1)
   * 

Practical Examples

Example 1: Type-Safe Structure

• * // For wire protocol (network or storage)
  * typedef struct {
  *     uint32_t message_id;      // Always 4 bytes
  *     uint16_t length;          // Always 2 bytes
  *     int16_t temperature;      // -50°C to +50°C
  *     uint8_t flags;            // Bit flags
  * } train_msg_t;
  *
  * // Size is predictable on ALL platforms
  * STATIC_ASSERT(sizeof(train_msg_t) == 9);
  * 

Example 2: Sized Counters

• * uint16_t packet_count;   // 0-65535 packets
  * uint32_t byte_count;     // 0-4B packets
  * uint64_t total_uptime_ms; // Milliseconds since boot
  * 

Best Practices

• 1. Never use bare int, long, char
• - Always explicit type: int32_t, uint8_t, etc.
• - Makes size guarantees visible
• 2. Match type to purpose
• - 16-bit counters: values 0-65535?
• - 32-bit time: milliseconds for ~49 days?
• - Don't over-allocate
• 3. Use uint8_t for bytes
• - Not unsigned char (confusing)
• - Not int (wrong size)
• - Always uint8_t for byte arrays
• 4. Use bool for single flags
• - bool enabled = true;
• - For multiple flags: uint32_t flags; with bit manipulation
• 5. Watch for overflow
• - uint8_t max = 255; max++; // Wraps to 0
• - int32_t sum = MAX + 1; // Undefined behavior!
• - Use next size up if needed

See Also

• - Types Module - Architecture for implementation details
• - Cast Module - User Guide for safe type conversions
• */