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