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/*
** SCCS ID: @(#)bootstrap.h 2.4 1/22/25
**
** @file bootstrap.h
**
** @author K. Reek
** @author Warren R. Carithers, Garrett C. Smith
**
** Addresses where various stuff goes in memory.
*/
#ifndef BOOTSTRAP_H_
#define BOOTSTRAP_H_
/*
** The boot device
*/
#define BDEV_FLOPPY 0x00
#define BDEV_USB 0x80 /* hard drive */
#define BDEV BDEV_USB /* default */
/*
** Bootstrap definitions
*/
#define BOOT_SEG 0x07c0 /* 07c0:0000 */
#define BOOT_DISP 0x0000
#define BOOT_ADDR ((BOOT_SEG << 4) + BOOT_DISP)
#define PART2_DISP 0x0200 /* 07c0:0200 */
#define PART2_ADDR ((BOOT_SEG << 4) + PART2_DISP)
#define SECTOR_SIZE 0x200 /* 512 bytes */
/* Note: this assumes the bootstrap is two sectors long! */
#define BOOT_SIZE (SECTOR_SIZE + SECTOR_SIZE)
#define OFFSET_LIMIT (0x10000 - SECTOR_SIZE)
#define BOOT_SP_DISP 0x4000 /* stack pointer 07c0:4000, or 0xbc00 */
#define BOOT_SP_ADDR ((BOOT_SEG << 4) + BOOT_SP_DISP)
#define SECTOR1_END (BOOT_ADDR + SECTOR_SIZE)
#define SECTOR2_END (BOOT_ADDR + BOOT_SIZE)
// location of the user blob data
// (three halfwords of data)
#define USER_BLOB_DATA (SECTOR2_END - 12)
/*
** The target program itself
*/
#define TARGET_SEG 0x00001000 /* 1000:0000 */
#define TARGET_ADDR 0x00010000 /* and upward */
#define TARGET_STACK 0x00010000 /* and downward */
/*
** The Global Descriptor Table (0000:0500 - 0000:2500)
*/
#define GDT_SEG 0x00000050
#define GDT_ADDR 0x00000500
/* segment register values */
#define GDT_LINEAR 0x0008 /* All of memory, R/W */
#define GDT_CODE 0x0010 /* All of memory, R/E */
#define GDT_DATA 0x0018 /* All of memory, R/W */
#define GDT_STACK 0x0020 /* All of memory, R/W */
/*
** The Interrupt Descriptor Table (0000:2500 - 0000:2D00)
*/
#define IDT_SEG 0x00000250
#define IDT_ADDR 0x00002500
/*
** Additional I/O ports used by the bootstrap code
*/
// keyboard controller
#define KBD_DATA 0x60
#define KBD_CMD 0x64
#define KBD_STAT 0x64
// status register bits
#define KBD_OBSTAT 0x01
#define KBD_IBSTAT 0x02
#define KBD_SYSFLAG 0x04
#define KBD_CMDDAT 0x08
// commands
#define KBD_P1_DISABLE 0xad
#define KBD_P1_ENABLE 0xae
#define KBD_RD_OPORT 0xd0
#define KBD_WT_OPORT 0xd1
#ifdef ASM_SRC
// segment descriptor macros for use in assembly source files
// layout:
// .word lower 16 bits of limit
// .word lower 16 bits of base
// .byte middle 8 bits of base
// .byte type byte
// .byte granularity byte
// .byte upper 8 bits of base
// we use 4K units, so we ignore the lower 12 bits of the limit
#define SEGNULL .word 0, 0, 0, 0
#define SEGMENT(base, limit, dpl, type) \
.word(((limit) >> 12) & 0xffff); \
.word((base) & 0xffff); \
.byte(((base) >> 16) & 0xff); \
.byte(SEG_PRESENT | (dpl) | SEG_NON_SYSTEM | (type)); \
.byte(SEG_GRAN_4KBYTE | SEG_DB_32BIT | (((limit) >> 28) & 0xf)); \
.byte(((base) >> 24) & 0xff)
#endif /* ASM_SRC */
#endif
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