 C166 User's Guide | |
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C166 User's Guide
C166 Introduction Compiling Programs Language Extensions Preprocessor Advanced Programming Sections, Classes, and Groups
Special Sections Locating Sections Customization Files Startup Code STARTUP.A66 START167.A66 Basic I/O Memory Allocation TRAPS.C Optimizer Optimizer Options General Optimizations 80C166-Specific Optimizations Global Register Coloring DPP Registers Stacks System Stack User Stack Stack Sizes System Stack Size User Stack Size XBUS Memory and Peripherals On-chip XRAM XBUS Peripherals Interfacing C to Assembler Function Parameters Function Return Values Using the SRC Directive Register Usage Example Routines TINY Model SMALL Model COMPACT Model MEDIUM Model LARGE Model Data Storage Formats Bit Variables 1-byte Scalars 2-byte Scalars 4-byte Scalars float Scalars float Errors double Scalars double Errors near Pointers far Pointers huge Pointers xhuge Pointers Absolute Memory Access Absolute Access Macros Linker Location Controls Debugging Error Messages Library Reference Appendixhuge Pointers
Pointers to huge objects are stored using four bytes (32 bits). The bytes are stored little endian or low to high order. The first word contains the 16-bit memory offset. The second word contains the segment number. The memory address is calculated as follows:
Address = (Segment * 0x10000L) + Offset
A huge pointer is stored in memory at a word boundary as follows:
| Address+0 | Address+1 | Address+2 | Address+3 | |
|---|---|---|---|---|
| Contents | Offset (LSB) | Offset (MSB) | Segment (LSB) | Segment (MSB) |
A huge pointer can access objects up to 64K in size in any memory area. Objects larger than 64K must be accessed using xhuge pointers.
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