/* At entry, the processor is in 16 bit real mode and the code is being
* executed from an address it was not linked to. Code must be pic and
* 32 bit sensitive until things are fixed up.
*
* Also be very careful as the stack is at the rear end of the interrupt
* table so using a noticeable amount of stack space is a no-no.
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL )
#include <librm.h>
#include <config/general.h>
#include <config/branding.h>
#define PNP_SIGNATURE ( '$' + ( 'P' << 8 ) + ( 'n' << 16 ) + ( 'P' << 24 ) )
#define PMM_SIGNATURE ( '$' + ( 'P' << 8 ) + ( 'M' << 16 ) + ( 'M' << 24 ) )
#define PCI_SIGNATURE ( 'P' + ( 'C' << 8 ) + ( 'I' << 16 ) + ( ' ' << 24 ) )
#define STACK_MAGIC ( 'L' + ( 'R' << 8 ) + ( 'E' << 16 ) + ( 'T' << 24 ) )
#define PMM_ALLOCATE 0x0000
#define PMM_FIND 0x0001
#define PMM_HANDLE_BASE ( ( ( 'F' - 'A' + 1 ) << 26 ) + \
( ( 'E' - 'A' + 1 ) << 21 ) + \
( ( 'N' - 'A' + 1 ) << 16 ) )
#define PMM_HANDLE_BASE_IMAGE_SOURCE \
( PMM_HANDLE_BASE | 0x00001000 )
#define PMM_HANDLE_BASE_DECOMPRESS_TO \
( PMM_HANDLE_BASE | 0x00002000 )
#define PCI_FUNC_MASK 0x07
/* ROM banner timeout, converted to a number of (18Hz) timer ticks. */
#define ROM_BANNER_TIMEOUT_TICKS ( ( 18 * ROM_BANNER_TIMEOUT ) / 10 )
/* Allow payload to be excluded from ROM size
*/
#if ROMPREFIX_EXCLUDE_PAYLOAD
#define ZINFO_TYPE_ADxB "ADHB"
#define ZINFO_TYPE_ADxW "ADHW"
#else
#define ZINFO_TYPE_ADxB "ADDB"
#define ZINFO_TYPE_ADxW "ADDW"
#endif
/* Allow ROM to be marked as containing multiple images
*/
#if ROMPREFIX_MORE_IMAGES
#define INDICATOR 0x00
#else
#define INDICATOR 0x80
#endif
/* Default to building a PCI ROM if no bus type is specified
*/
#ifndef BUSTYPE
#define BUSTYPE "PCIR"
#endif
.section ".note.GNU-stack", "", @progbits
.text
.code16
.arch i386
.section ".prefix", "ax", @progbits
.globl _rom_start
_rom_start:
.org 0x00
romheader:
.word 0xAA55 /* BIOS extension signature */
romheader_size: .byte 0 /* Size in 512-byte blocks */
jmp init /* Initialisation vector */
checksum:
.byte 0
.org 0x10
.word ipxeheader
.org 0x16
.word undiheader
.ifeqs BUSTYPE, "PCIR"
.org 0x18
.word pciheader
.endif
.org 0x1a
.word pnpheader
.size romheader, . - romheader
.section ".zinfo.fixup", "a", @progbits /* Compressor fixups */
.ascii ZINFO_TYPE_ADxB
.long romheader_size
.long 512
.long 0
.previous
.ifeqs BUSTYPE, "PCIR"
.balign 4
pciheader:
.ascii "PCIR" /* Signature */
.word pci_vendor_id /* Vendor identification */
.word pci_device_id /* Device identification */
.word ( pci_devlist - pciheader ) /* Device list pointer */
.word pciheader_len /* PCI data structure length */
.byte 0x03 /* PCI data structure revision */
.byte 0x00, 0x00, 0x02 /* Class code */
pciheader_image_length:
.word 0 /* Image length */
.word 0x0001 /* Revision level */
.byte 0x00 /* Code type */
.byte INDICATOR /* Last image indicator */
pciheader_runtime_length:
.word 0 /* Maximum run-time image length */
.word 0x0000 /* Configuration utility code header */
.word 0x0000 /* DMTF CLP entry point */
.equ pciheader_len, . - pciheader
.size pciheader, . - pciheader
/* PCI additional device list (filled in by linker) */
.section ".pci_devlist.00000000", "a", @progbits
pci_devlist:
.previous
.section ".pci_devlist.ffffffff", "a", @progbits
pci_devlist_end:
.short 0x0000 /* List terminator */
.previous
/* Ensure that terminator is always present */
.reloc pciheader, RELOC_TYPE_NONE, pci_devlist_end
.section ".zinfo.fixup", "a", @progbits /* Compressor fixups */
.ascii ZINFO_TYPE_ADxW
.long pciheader_image_length
.long 512
.long 0
.ascii "ADHW"
.long pciheader_runtime_length
.long 512
.long 0
.previous
.endif /* PCIR */
/* PnP doesn't require any particular alignment, but IBM
* BIOSes will scan on 16-byte boundaries rather than using
* the offset stored at 0x1a
*/
.balign 16
pnpheader:
.ascii "$PnP" /* Signature */
.byte 0x01 /* Structure revision */
.byte ( pnpheader_len / 16 ) /* Length (in 16 byte increments) */
.word 0x0000 /* Offset of next header */
.byte 0x00 /* Reserved */
.byte 0x00 /* Checksum */
.long 0x00000000 /* Device identifier */
.word mfgstr /* Manufacturer string */
.word prodstr /* Product name */
.byte 0x02 /* Device base type code */
.byte 0x00 /* Device sub-type code */
.byte 0x00 /* Device interface type code */
.byte 0xf4 /* Device indicator */
.word 0x0000 /* Boot connection vector */
.word 0x0000 /* Disconnect vector */
.word bev_entry /* Boot execution vector */
.word 0x0000 /* Reserved */
.word 0x0000 /* Static resource information vector*/
.equ pnpheader_len, . - pnpheader
.size pnpheader, . - pnpheader
/* Manufacturer string */
mfgstr:
.asciz "https://ipxe.org"
.size mfgstr, . - mfgstr
/* Product string
*
* Defaults to PRODUCT_SHORT_NAME. If the ROM image is writable at
* initialisation time, it will be filled in to include the PCI
* bus:dev.fn number of the card as well.
*/
prodstr:
.ascii PRODUCT_SHORT_NAME
.ifeqs BUSTYPE, "PCIR"
prodstr_separator:
.byte 0
.ascii "(PCI "
prodstr_pci_id:
.ascii "xx:xx.x)" /* Filled in by init code */
.endif /* PCIR */
.byte 0
.size prodstr, . - prodstr
.globl undiheader
.weak undiloader
.balign 4
undiheader:
.ascii "UNDI" /* Signature */
.byte undiheader_len /* Length of structure */
.byte 0 /* Checksum */
.byte 0 /* Structure revision */
.byte 0,1,2 /* PXE version: 2.1.0 */
.word undiloader /* Offset to loader routine */
.word _data16_memsz /* Stack segment size */
.word _data16_memsz /* Data segment size */
.word _text16_memsz /* Code segment size */
.ascii BUSTYPE /* Bus type */
.equ undiheader_len, . - undiheader
.size undiheader, . - undiheader
.balign 4
ipxeheader:
.ascii "iPXE" /* Signature */
.byte ipxeheader_len /* Length of structure */
.byte 0 /* Checksum */
shrunk_rom_size:
.byte 0 /* Shrunk size (in 512-byte blocks) */
.byte 0 /* Reserved */
build_id:
.long _build_id /* Randomly-generated build ID */
.equ ipxeheader_len, . - ipxeheader
.size ipxeheader, . - ipxeheader
.section ".zinfo.fixup", "a", @progbits /* Compressor fixups */
.ascii "ADHB"
.long shrunk_rom_size
.long 512
.long 0
.previous
/* Initialisation (called once during POST)
*
* Determine whether or not this is a PnP system via a signature
* check. If it is PnP, return to the PnP BIOS indicating that we are
* a boot-capable device; the BIOS will call our boot execution vector
* if it wants to boot us. If it is not PnP, hook INT 19.
*/
init:
/* Preserve registers, clear direction flag, set %ds=%cs */
pushaw
pushw %ds
pushw %es
pushw %fs
pushw %gs
cld
pushw %cs
popw %ds
/* Print message as early as possible */
movw $init_message, %si
xorw %di, %di
call print_message
/* Store PCI 3.0 runtime segment address for later use, if
* applicable.
*/
.ifeqs BUSTYPE, "PCIR"
movw %bx, %gs
.endif
/* Store PCI bus:dev.fn address, print PCI bus:dev.fn, and add
* PCI bus:dev.fn to product name string, if applicable.
*/
.ifeqs BUSTYPE, "PCIR"
xorw %di, %di
call print_space
movw %ax, init_pci_busdevfn
call print_pci_busdevfn
movw $prodstr_pci_id, %di
call print_pci_busdevfn
movb $( ' ' ), prodstr_separator
.endif
/* Print segment address */
xorw %di, %di
call print_space
movw %cs, %ax
call print_hex_word
/* Check for PCI BIOS version, if applicable */
.ifeqs BUSTYPE, "PCIR"
pushl %ebx
pushl %edx
pushl %edi
stc
movw $0xb101, %ax
int $0x1a
jc no_pci3
cmpl $PCI_SIGNATURE, %edx
jne no_pci3
testb %ah, %ah
jnz no_pci3
movw $init_message_pci, %si
xorw %di, %di
call print_message
movb %bh, %al
call print_hex_nibble
movb $( '.' ), %al
call print_character
movb %bl, %al
call print_hex_byte
cmpb $3, %bh
jb no_pci3
/* PCI >=3.0: leave %gs as-is if sane */
movw %gs, %ax
cmpw $0xa000, %ax /* Insane if %gs < 0xa000 */
jb pci3_insane
movw %cs, %bx /* Sane if %cs == %gs */
cmpw %bx, %ax
je 1f
movzbw romheader_size, %cx /* Sane if %cs+len <= %gs */
shlw $5, %cx
addw %cx, %bx
cmpw %bx, %ax
jae 1f
movw %cs, %bx /* Sane if %gs+len <= %cs */
addw %cx, %ax
cmpw %bx, %ax
jbe 1f
pci3_insane: /* PCI 3.0 with insane %gs value: print error and ignore %gs */
movb $( '!' ), %al
call print_character
movw %gs, %ax
call print_hex_word
no_pci3:
/* PCI <3.0: set %gs (runtime segment) = %cs (init-time segment) */
pushw %cs
popw %gs
1: popl %edi
popl %edx
popl %ebx
.endif /* PCIR */
/* Check for PnP BIOS. Although %es:di should point to the
* PnP BIOS signature on entry, some BIOSes fail to do this.
*/
movw $( 0xf000 - 1 ), %bx
pnp_scan:
incw %bx
jz no_pnp
movw %bx, %es
cmpl $PNP_SIGNATURE, %es:0
jne pnp_scan
xorw %dx, %dx
xorw %si, %si
movzbw %es:5, %cx
1: es lodsb
addb %al, %dl
loop 1b
jnz pnp_scan
/* Is PnP: print PnP message */
movw $init_message_pnp, %si
xorw %di, %di
call print_message
jmp pnp_done
no_pnp: /* Not PnP-compliant - hook INT 19 */
#ifdef NONPNP_HOOK_INT19
movw $init_message_int19, %si
xorw %di, %di
call print_message
xorw %ax, %ax
movw %ax, %es
pushl %es:( 0x19 * 4 )
popl orig_int19
pushw %gs /* %gs contains runtime %cs */
pushw $int19_entry
popl %es:( 0x19 * 4 )
#endif /* NONPNP_HOOK_INT19 */
pnp_done:
/* Check for PMM */
movw $( 0xe000 - 1 ), %bx
pmm_scan:
incw %bx
jz no_pmm
movw %bx, %es
cmpl $PMM_SIGNATURE, %es:0
jne pmm_scan
xorw %dx, %dx
xorw %si, %si
movzbw %es:5, %cx
1: es lodsb
addb %al, %dl
loop 1b
jnz pmm_scan
/* PMM found: print PMM message */
movw $init_message_pmm, %si
xorw %di, %di
call print_message
/* We have PMM and so a 1kB stack: preserve whole registers */
pushal
/* Allocate image source PMM block. Round up the size to the
* nearest 4kB (8 512-byte sectors) to work around AMI BIOS bugs.
*/
movzbl romheader_size, %ecx
addw extra_size, %cx
addw $0x0007, %cx /* Round up to multiple of 8 512-byte sectors */
andw $0xfff8, %cx
shll $5, %ecx
movl $PMM_HANDLE_BASE_IMAGE_SOURCE, %ebx
movw $get_pmm_image_source, %bp
call get_pmm
movl %esi, image_source
jz 1f
/* Copy ROM to image source PMM block */
pushw %es
xorw %ax, %ax
movw %ax, %es
movl %esi, %edi
xorl %esi, %esi
movzbl romheader_size, %ecx
shll $7, %ecx
addr32 rep movsl /* PMM presence implies flat real mode */
popw %es
/* Shrink ROM */
movb shrunk_rom_size, %al
movb %al, romheader_size
1: /* Allocate decompression PMM block. Allow 4kB for page
* alignment and round up the size to the nearest 128kB, then
* use the size within the PMM handle; this allows the same
* decompression area to be shared between multiple iPXE ROMs
* even with differing build IDs
*/
movl $_textdata_memsz_pgh, %ecx
addl $( 0x00000100 /* 4kB */ + 0x00001fff /* 128kB - 1 */ ), %ecx
andl $( 0xffffe000 /* ~( 128kB - 1 ) */ ), %ecx
movl %ecx, %ebx
shrw $12, %bx
orl $PMM_HANDLE_BASE_DECOMPRESS_TO, %ebx
movw $get_pmm_decompress_to, %bp
call get_pmm
addl $( 0x00000fff /* 4kB - 1 */ ), %esi
andl $( 0xfffff000 /* ~( 4kB - 1 ) */ ), %esi
movl %esi, decompress_to
/* Restore registers */
popal
no_pmm:
/* Update checksum */
xorw %bx, %bx
xorw %si, %si
movzbw romheader_size, %cx
shlw $9, %cx
1: lodsb
addb %al, %bl
loop 1b
subb %bl, checksum
/* Copy self to option ROM space, if applicable. Required for
* PCI3.0, which loads us to a temporary location in low
* memory. Will be a no-op for lower PCI versions.
*/
.ifeqs BUSTYPE, "PCIR"
/* Get runtime segment address and length */
movw %gs, %ax
movw %ax, %es
movzbw romheader_size, %cx
/* Print runtime segment address */
xorw %di, %di
call print_space
call print_hex_word
/* Fail if we have insufficient space in final location */
movw %cs, %si
cmpw %si, %ax
je 1f
cmpw pciheader_runtime_length, %cx
jbe 1f
movb $( '!' ), %al
call print_character
xorw %cx, %cx
1: /* Copy to final location */
shlw $9, %cx
xorw %si, %si
xorw %di, %di
cs rep movsb
.endif
/* Skip prompt if this is not the first PCI function, if applicable */
.ifeqs BUSTYPE, "PCIR"
testb $PCI_FUNC_MASK, init_pci_busdevfn
jnz no_shell
.endif
/* Prompt for POST-time shell */
movw $init_message_prompt, %si
xorw %di, %di
call print_message
movw $prodstr, %si
call print_message
movw $init_message_dots, %si
call print_message
/* Wait for Ctrl-B */
movw $0xff02, %bx
call wait_for_key
/* Clear prompt */
pushf
xorw %di, %di
call print_kill_line
movw $init_message_done, %si
call print_message
popf
jnz no_shell
/* Ctrl-B was pressed: invoke iPXE. The keypress will be
* picked up by the initial shell prompt, and we will drop
* into a shell.
*/
xorl %ebp, %ebp /* Inhibit use of INT 15,e820 and INT 15,e801 */
pushw %cs
call exec
no_shell:
movb $( '\n' ), %al
xorw %di, %di
call print_character
/* Restore registers */
popw %gs
popw %fs
popw %es
popw %ds
popaw
/* Indicate boot capability to PnP BIOS, if present */
movw $0x20, %ax
lret
.size init, . - init
/* Attempt to find or allocate PMM block
*
* Parameters:
* %ecx : size of block to allocate, in paragraphs
* %ebx : PMM handle base
* %bp : routine to check acceptability of found blocks
* %es:0000 : PMM structure
* Returns:
* %ebx : PMM handle
* %esi : allocated block address, or zero (with ZF set) if allocation failed
*/
get_pmm:
/* Preserve registers */
pushl %eax
pushw %di
movw $( ' ' ), %di
get_pmm_find:
/* Try to find existing block */
pushl %ebx /* PMM handle */
pushw $PMM_FIND
lcall *%es:7
addw $6, %sp
pushw %dx
pushw %ax
popl %esi
/* Treat 0xffffffff (not supported) as 0x00000000 (not found) */
incl %esi
jz get_pmm_allocate
decl %esi
jz get_pmm_allocate
/* Block found - check acceptability */
call *%bp
jnc get_pmm_done
/* Block not acceptable - increment handle and retry */
incl %ebx
jmp get_pmm_find
get_pmm_allocate:
/* Block not found - try to allocate new block */
pushw $0x0002 /* Extended memory */
pushl %ebx /* PMM handle */
pushl %ecx /* Length */
pushw $PMM_ALLOCATE
lcall *%es:7
addw $12, %sp
pushw %dx
pushw %ax
popl %esi
movw $( '+' ), %di /* Indicate allocation attempt */
get_pmm_done:
/* Print block address */
movw %di, %ax
xorw %di, %di
call print_character
movl %esi, %eax
call print_hex_dword
/* Treat 0xffffffff (not supported) as 0x00000000 (allocation
* failed), and set ZF to indicate a zero result.
*/
incl %esi
jz 1f
decl %esi
1: /* Restore registers and return */
popw %di
popl %eax
ret
.size get_pmm, . - get_pmm
/* Check acceptability of image source block */
get_pmm_image_source:
pushw %es
xorw %ax, %ax
movw %ax, %es
movl build_id, %eax
addr32 cmpl %es:build_id(%esi), %eax
je 1f
stc
1: popw %es
ret
.size get_pmm_image_source, . - get_pmm_image_source
/* Check acceptability of decompression block */
get_pmm_decompress_to:
clc
ret
.size get_pmm_decompress_to, . - get_pmm_decompress_to
/*
* Note to hardware vendors:
*
* If you wish to brand this boot ROM, please do so by defining the
* strings PRODUCT_NAME and PRODUCT_SHORT_NAME in config/branding.h.
*
* While nothing in the GPL prevents you from removing all references
* to iPXE or https://ipxe.org, we prefer you not to do so.
*
* If you have an OEM-mandated branding requirement that cannot be
* satisfied simply by defining PRODUCT_NAME and PRODUCT_SHORT_NAME,
* please contact us.
*
* [ Including an ASCII NUL in PRODUCT_NAME is considered to be
* bypassing the spirit of this request! ]
*/
init_message:
.ascii "\n"
.ascii PRODUCT_NAME
.ascii "\n"
.ascii PRODUCT_SHORT_NAME
.ascii " ("
.ascii PRODUCT_URI
.asciz ")"
.size init_message, . - init_message
.ifeqs BUSTYPE, "PCIR"
init_message_pci:
.asciz " PCI"
.size init_message_pci, . - init_message_pci
.endif /* PCIR */
init_message_pnp:
.asciz " PnP"
.size init_message_pnp, . - init_message_pnp
init_message_pmm:
.asciz " PMM"
.size init_message_pmm, . - init_message_pmm
init_message_int19:
.asciz " INT19"
.size init_message_int19, . - init_message_int19
init_message_prompt:
.asciz "\nPress Ctrl-B to configure "
.size init_message_prompt, . - init_message_prompt
init_message_dots:
.asciz "..."
.size init_message_dots, . - init_message_dots
init_message_done:
.asciz "\n\n"
.size init_message_done, . - init_message_done
/* PCI bus:dev.fn
*
*/
.ifeqs BUSTYPE, "PCIR"
init_pci_busdevfn:
.word 0
.size init_pci_busdevfn, . - init_pci_busdevfn
.endif /* PCIR */
/* Image source area
*
* May be either zero (indicating to use option ROM space as source),
* or within a PMM-allocated block.
*/
.globl image_source
image_source:
.long 0
.size image_source, . - image_source
/* Additional image source size (in 512-byte sectors)
*
*/
extra_size:
.word 0
.size extra_size, . - extra_size
/* Temporary decompression area
*
* May be either zero (indicating to use default decompression area in
* high memory), or within a PMM-allocated block.
*/
.globl decompress_to
decompress_to:
.long 0
.size decompress_to, . - decompress_to
/* Boot Execution Vector entry point
*
* Called by the PnP BIOS when it wants to boot us.
*/
bev_entry:
orl $0xffffffff, %ebp /* Allow arbitrary relocation */
pushw %cs
call exec
lret
.size bev_entry, . - bev_entry
/* INT19 entry point
*
* Called via the hooked INT 19 if we detected a non-PnP BIOS. We
* attempt to return via the original INT 19 vector (if we were able
* to store it).
*/
int19_entry:
pushw %cs
popw %ds
/* Prompt user to press B to boot */
movw $int19_message_prompt, %si
xorw %di, %di
call print_message
movw $prodstr, %si
call print_message
movw $int19_message_dots, %si
call print_message
movw $0xdf4e, %bx
call wait_for_key
pushf
xorw %di, %di
call print_kill_line
movw $int19_message_done, %si
call print_message
popf
jz 1f
/* Leave keypress in buffer and start iPXE. The keypress will
* cause the usual initial Ctrl-B prompt to be skipped.
*/
orl $0xffffffff, %ebp /* Allow arbitrary relocation */
pushw %cs
call exec
1: /* Try to call original INT 19 vector */
movl %cs:orig_int19, %eax
testl %eax, %eax
je 2f
ljmp *%cs:orig_int19
2: /* No chained vector: issue INT 18 as a last resort */
int $0x18
.size int19_entry, . - int19_entry
orig_int19:
.long 0
.size orig_int19, . - orig_int19
int19_message_prompt:
.asciz "Press N to skip booting from "
.size int19_message_prompt, . - int19_message_prompt
int19_message_dots:
.asciz "..."
.size int19_message_dots, . - int19_message_dots
int19_message_done:
.asciz "\n\n"
.size int19_message_done, . - int19_message_done
/* Execute as a boot device
*
*/
exec: /* Set %ds = %cs */
pushw %cs
popw %ds
/* Print message as soon as possible */
movw $prodstr, %si
xorw %di, %di
call print_message
movw $exec_message_pre_install, %si
call print_message
/* Store magic word on BIOS stack and remember BIOS %ss:sp */
pushl $STACK_MAGIC
movw %ss, %cx
movw %sp, %dx
/* Obtain a reasonably-sized temporary stack */
xorw %bx, %bx
movw %bx, %ss
movw $0x7c00, %sp
/* Install iPXE */
call alloc_basemem
movl image_source, %esi
movl decompress_to, %edi
call install_prealloc
/* Print message indicating successful installation */
movw $exec_message_post_install, %si
xorw %di, %di
call print_message
/* Set up real-mode stack */
movw %bx, %ss
movw $_estack16, %sp
/* Jump to .text16 segment */
pushw %ax
pushw $1f
lret
.section ".text16", "awx", @progbits
1:
/* Retrieve PCI bus:dev.fn, if applicable */
.ifeqs BUSTYPE, "PCIR"
movw init_pci_busdevfn, %ax
.endif
/* Set up %ds for access to .data16 */
movw %bx, %ds
/* Store PCI bus:dev.fn, if applicable */
.ifeqs BUSTYPE, "PCIR"
#ifdef AUTOBOOT_ROM_FILTER
movw %ax, autoboot_busdevfn
#endif /* AUTOBOOT_ROM_FILTER */
.endif
/* Run iPXE */
virtcall main
/* Set up flat real mode for return to BIOS */
call flatten_real_mode
/* Uninstall iPXE */
call uninstall
/* Restore BIOS stack */
movw %cx, %ss
movw %dx, %sp
/* Check magic word on BIOS stack */
popl %eax
cmpl $STACK_MAGIC, %eax
jne 1f
/* BIOS stack OK: return to caller */
lret
1: /* BIOS stack corrupt: use INT 18 */
int $0x18
.previous
exec_message_pre_install:
.asciz " starting execution..."
.size exec_message_pre_install, . - exec_message_pre_install
exec_message_post_install:
.asciz "ok\n"
.size exec_message_post_install, . - exec_message_post_install
/* Wait for key press specified by %bl (masked by %bh)
*
* Used by init and INT19 code when prompting user. If the specified
* key is pressed, it is left in the keyboard buffer.
*
* Returns with ZF set iff specified key is pressed.
*/
wait_for_key:
/* Preserve registers */
pushw %cx
pushw %ax
1: /* Empty the keyboard buffer before waiting for input */
movb $0x01, %ah
int $0x16
jz 2f
xorw %ax, %ax
int $0x16
jmp 1b
2: /* Wait for a key press */
movw $ROM_BANNER_TIMEOUT_TICKS, %cx
3: decw %cx
js 99f /* Exit with ZF clear */
/* Wait for timer tick to be updated */
call wait_for_tick
/* Check to see if a key was pressed */
movb $0x01, %ah
int $0x16
jz 3b
/* Check to see if key was the specified key */
andb %bh, %al
cmpb %al, %bl
je 99f /* Exit with ZF set */
/* Not the specified key: remove from buffer and stop waiting */
pushfw
xorw %ax, %ax
int $0x16
popfw /* Exit with ZF clear */
99: /* Restore registers and return */
popw %ax
popw %cx
ret
.size wait_for_key, . - wait_for_key
/* Wait for timer tick
*
* Used by wait_for_key
*/
wait_for_tick:
pushl %eax
pushw %fs
movw $0x40, %ax
movw %ax, %fs
movl %fs:(0x6c), %eax
1: pushf
sti
hlt
popf
cmpl %fs:(0x6c), %eax
je 1b
popw %fs
popl %eax
ret
.size wait_for_tick, . - wait_for_tick
/* Drag in objects via _rom_start */
REQUIRING_SYMBOL ( _rom_start )
/* Drag in ROM configuration */
REQUIRE_OBJECT ( config_romprefix )
