go32 unit

GO32 - access to the 32-bit DOS extender.

This document describes the GO32 unit for the Free Pascal compiler under dos. It was donated by Thomas Schatzl (tom_at_work@geocities.com), for which my thanks. This unit was first written for dos by Florian Klaempfl.

Only the GO32V2 DPMI mode is discussed by me here due to the fact that new applications shouldn't be created with the older GO32V1 model. The go32v2 version is much more advanced and better. Additionally a lot of functions only work in DPMI mode anyway. I hope the following explanations and introductions aren't too confusing at all. If you notice an error or bug send it to the FPC mailing list or directly to me. So let's get started and happy and error free coding I wish you.... Thomas Schatzl, 25. August 1998

Classes and records

`tdpmiversioninfo`	record	Structure describing DPMI version.
`tmeminfo`	record	Memory information record.
`trealregs`	record	Record describing all processor registers.
`tseginfo`	record	Record to store 48-bits pointer.

Procedures and functions

`allocate_ldt_descriptors`	function	Allocate a number of descriptors.
`allocate_memory_block`	function	Allocate a block of linear memory.
`copyfromdos`	procedure	Copy data from DOS to heap.
`copytodos`	procedure	Copy data from heap to DOS memory.
`create_code_segment_alias_descriptor`	function	Create new descriptor from existing descriptor.
`disable`	procedure	Disable hardware interrupts.
`dpmi_dosmemfillchar`	procedure	Fill DOS memory with a character.
`dpmi_dosmemfillword`	procedure	Fill DOS memory with a word value.
`dpmi_dosmemget`	procedure	Move data from DOS memory to DPMI memory.
`dpmi_dosmemmove`	procedure	Move DOS memory.
`dpmi_dosmemput`	procedure	Move data from DPMI memory to DOS memory.
`enable`	procedure	Enable hardware interrupts.
`free_ldt_descriptor`	function	Free a descriptor.
`free_linear_addr_mapping`	function	? No description available.
`free_memory_block`	function	Free allocated memory block.
`free_rm_callback`	function	Release real mode callback.
`get_cs`	function	Get CS selector.
`get_descriptor_access_right`	function	Get descriptor's access rights.
`get_dpmi_version`	function	Return DPMI information.
`get_ds`	function	Get DS Selector.
`get_exception_handler`	function	Return current exception handler.
`get_linear_addr`	function	Convert physical to linear address.
`get_meminfo`	function	Return information on the available memory.
`get_next_selector_increment_value`	function	Return selector increment value.
`get_page_attributes`	function	? No description available.
`get_page_size`	function	Return the page size.
`get_pm_exception_handler`	function	Get protected mode exception handler.
`get_pm_interrupt`	function	Return protected mode interrupt handler.
`get_rm_callback`	function	Return real mode callback.
`get_rm_interrupt`	function	Get real mode interrupt vector.
`get_run_mode`	function	Return current run mode.
`get_segment_base_address`	function	Return base address from descriptor table.
`get_segment_limit`	function	Return segment limits from descriptor.
`get_ss`	function	Return SS selector.
`global_dos_alloc`	function	Allocate DOS real mode memory.
`global_dos_free`	function	Free DOS memory block.
`inportb`	function	Read byte from I/O port.
`inportl`	function	Read longint from I/O port.
`inportw`	function	Read word from I/O port.
`lock_code`	function	Lock code memory range.
`lock_data`	function	Lock data memory range.
`lock_linear_region`	function	Lock linear memory region.
`map_device_in_memory_block`	function	Map a device into program's memory space.
`outportb`	procedure	Write byte to I/O port.
`outportl`	procedure	Write longint to I/O port.
`outportw`	procedure	Write word to I/O port.
`realintr`	function	Simulate interrupt.
`request_linear_region`	function	Request linear address region.
`seg_fillchar`	procedure	Fill segment with byte value.
`seg_fillword`	procedure	Fill segment with word value.
`seg_move`	procedure	Move data between 2 locations.
`segment_to_descriptor`	function	Map segment address to descriptor.
`set_descriptor_access_right`	function	Set access rights to memory descriptor.
`set_exception_handler`	function	Set exception handler.
`set_page_attributes`	function	? No description available.
`set_pm_exception_handler`	function	Set protected mode exception handler.
`set_pm_interrupt`	function	Set protected mode interrupt handler.
`set_rm_interrupt`	function	Set real mode interrupt handler.
`set_segment_base_address`	function	Set descriptor's base address.
`set_segment_limit`	function	Set descriptor limit.
`tb_offset`	function	Return DOS transfer buffer offset.
`tb_segment`	function	Return DOS transfer buffer segment.
`tb_size`	function	Return DOS transfer memory buffer size.
`transfer_buffer`	function	Return offset of DOS transfer buffer.
`unlock_code`	function	Unlock code segment.
`unlock_data`	function	Unlock data segment.
`unlock_linear_region`	function	Unlock linear memory region.

Types

registers type Alias for .

Constants

`auxcarryflag`	constant	Check for auxiliary carry flag in .
`carryflag`	constant	Check for carry flag in .
`directionflag`	constant	Check for direction flag in .
`dosmemfillchar`	constant	Fill a region of DOS memory with a specific byte-sized value.
`dosmemfillword`	constant	Fill a region of DOS memory with a specific word-sized value.
`dosmemget`	constant	Copy data from DOS memory to the heap.
`dosmemmove`	constant	Move data between 2 DOS real mode memory locations.
`dosmemput`	constant	Copy data from the heap to DOS real mode memory.
`interruptflag`	constant	Check for interrupt flag in .
`overflowflag`	constant	Check for overflow flag in .
`parityflag`	constant	Check for parity flag in .
`rm_dpmi`	constant	return value: DPMI (e.g. dos box or 386Max).
`rm_raw`	constant	return value: raw (without HIMEM).
`rm_unknown`	constant	return value: Unknown runmode.
`rm_vcpi`	constant	return value: VCPI (with HIMEM and EMM386).
`rm_xms`	constant	return value: XMS (with HIMEM, without EMM386).
`signflag`	constant	Check for sign flag in .
`trapflag`	constant	Check for trap flag in .
`zeroflag`	constant	Check for zero flag in .

Variables

`dosmemselector`	variable	Selector to DOS memory.
`int31error`	variable	DPMI interrupt call result.

Topics

`CreatingInterruptHandlers`	topic	Creating your own interrupt handlers.
`DisablingInterrupts`	topic	Disabling interrupts.
`DosMemory`	topic	dos memory access.
`DPMI`	topic	What is DPMI.
`DPMIInterrupts`	topic	Handling interrupts with DPMI.
`DPMIvsProtectedInterrupts`	topic	Protected mode interrupts vs. Real mode interrupts.
`ExecutingInterrupts`	topic	Executing software interrupts.
`FPCspecs`	topic	FPC specialities.
`HardwareInterrupts`	topic	Hardware interrupts.
`InterruptHandling`	topic	Interrupt redirection.
`IOPorts`	topic	I/O port access.
`ProcessorAccess`	topic	Processor access.
`RealModeCallBacks`	topic	Real mode callbacks.
`SelectorsDescriptors`	topic	Selectors and descriptors.
`SoftwareInterrupts`	topic	Software interrupts.

An experiment, built from development snapshots. Not the official Free Pascal or Lazarus documentation.