+# pcboot - bootable PC demo/game kernel
+# Copyright (C) 2018 John Tsiombikas <nuclear@member.fsf.org>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY, without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <https://www.gnu.org/licenses/>.
+
# this is the second-stage boot loader
.code16
.section .boot2,"a"
- .extern ser_putchar
+ # make sure any BIOS call didn't re-enable interrupts
+ cli
+
+ # just in case we were loaded from floppy, turn all floppy motors off
+ call motor_off
mov $0x13, %ax
int $0x10
+ # load initial GDT/IDT
+ lgdt (gdt_lim)
+ lidt (idt_lim)
+ # enable protection
+ mov %cr0, %eax
+ or $1, %eax
+ mov %eax, %cr0
+ # inter-segment jump to set cs selector to segment 1
+ ljmp $0x8,$0f
+
+ .code32
+ # set all data selectors to segment 2
+0: mov $0x10, %ax
+ mov %ax, %ds
+ mov %ax, %ss
+ mov %ax, %es
+ mov %ax, %gs
+ mov %ax, %fs
+
movb $10, %al
call ser_putchar
+ call clearscr
+
+ mov $hello, %esi
+ call putstr
+
+ # enable A20 line
+ call enable_a20
+
+ call logohack
+
+ cli
+ hlt
+
+hello: .asciz "Switched to 32bit\n"
+
+ .align 4
+gdt_lim: .word 23
+gdt_base:.long gdt
+
+ .align 4
+idt_lim: .word 111
+idt_base:.long idt
+
+
+ .align 8
+gdt: # 0: null segment
+ .long 0
+ .long 0
+ # 1: code - base:0, lim:4g, G:4k, 32bit, avl, pres|app, dpl:0, type:code/non-conf/rd
+ .long 0x0000ffff
+ .long 0x00cf9a00
+ # 2: data - base:0, lim:4g, G:4k, 32bit, avl, pres|app, dpl:0, type:data/rw
+ .long 0x0000ffff
+ .long 0x00cf9200
+
+
+ .align 8
+idt: .space 104
+ # trap gate 13: general protection fault
+ .short prot_fault
+ .short 0x8
+ # type: trap, present, default
+ .short 0x8f00
+ .short 0
+
+gpf_msg: .asciz "GP fault "
+
+prot_fault:
+ mov (%esp), %eax
+ shr $3, %eax
+ call print_num
+ mov $64, %al
+ call putchar
+ mov 4(%esp), %eax
+ call print_num
+ mov $10, %al
+ call putchar
+ hlt
+
+ena20_msg: .asciz "A20 line enabled\n"
+
+enable_a20:
+ call test_a20
+ jnc a20done
+ call enable_a20_kbd
+ call test_a20
+ jnc a20done
+ call enable_a20_fast
+ call test_a20
+ jnc a20done
+ # keep trying ... we can't do anything useful without A20 anyway
+ jmp enable_a20
+a20done:
+ mov $ena20_msg, %esi
+ call putstr
+ ret
+
+ # CF = 1 if A20 test fails (not enabled)
+test_a20:
+ mov $0x07c000, %ebx
+ mov $0x17c000, %edx
+ movl $0xbaadf00d, (%ebx)
+ movl $0xaabbcc42, (%edx)
+ subl $0xbaadf00d, (%ebx)
+ ret
+
+ # enable A20 line through port 0x92 (fast A20)
+enable_a20_fast:
+ mov $ena20_fast_msg, %esi
+ call putstr
+
+ in $0x92, %al
+ or $2, %al
+ out %al, $0x92
+ ret
+
+ena20_fast_msg: .asciz "Attempting fast A20 enable\n"
+
+
+ # enable A20 line through the keyboard controller
+ .set KBC_DATA_PORT, 0x60
+ .set KBC_CMD_PORT, 0x64
+ .set KBC_STATUS_PORT, 0x64
+ .set KBC_CMD_RD_OUTPORT, 0xd0
+ .set KBC_CMD_WR_OUTPORT, 0xd1
+
+ .set KBC_STAT_OUT_RDY, 0x01
+ .set KBC_STAT_IN_FULL, 0x02
+
+enable_a20_kbd:
+ mov $ena20_kbd_msg, %esi
+ call putstr
+
+ call kbc_wait_write
+ mov $KBC_CMD_WR_OUTPORT, %al
+ out %al, $KBC_CMD_PORT
+ call kbc_wait_write
+ mov $0xdf, %al
+ out %al, $KBC_DATA_PORT
+ ret
+
+ena20_kbd_msg: .asciz "Attempting KBD A20 enable\n"
+
+ # wait until the keyboard controller is ready to accept another byte
+kbc_wait_write:
+ in $KBC_STATUS_PORT, %al
+ and $KBC_STAT_IN_FULL, %al
+ jnz kbc_wait_write
+ ret
+
+ # better print routines, since we're not constrainted by the 512b of
+ # the boot sector.
+cursor_x: .long 0
+cursor_y: .long 0
+
+putchar:
+ pusha
+ call ser_putchar
+
+ cmp $10, %al
+ jnz 0f
+ call video_newline
+ jmp 1f
+
+0: push %eax
+ mov cursor_y, %eax
+ mov $80, %ecx
+ mul %ecx
+ add cursor_x, %eax
+ mov %eax, %ebx
+ pop %eax
+
+ mov $0xb8000, %edx
+
+ # this looks retarded. in nasm: [ebx * 2 + edx]
+ mov %al, (%edx, %ebx, 2)
+ movb $7, 1(%edx, %ebx, 2)
+ incl cursor_x
+ cmpl $80, cursor_x
+ jnz 1f
+ call video_newline
+
+1: popa
+ ret
+
+ # expects string pointer in esi
+putstr:
+ mov (%esi), %al
+ cmp $0, %al
+ jz 0f
+ call putchar
+ inc %esi
+ jmp putstr
+0: ret
+
+ # expects number in eax
+print_num:
+ # save registers
+ pusha
+
+ mov $numbuf + 16, %esi
+ movb $0, (%esi)
+ mov $10, %ebx
+convloop:
+ xor %edx, %edx
+ div %ebx
+ add $48, %dl
+ dec %esi
+ mov %dl, (%esi)
+ cmp $0, %eax
+ jnz convloop
+
+ call putstr
+
+ # restore regs
+ popa
+ ret
+
+
+video_newline:
+ movl $0, cursor_x
+ incl cursor_y
+ cmpl $25, cursor_y
+ jnz 0f
+ call scrollup
+ decl cursor_y
+0: ret
+
+scrollup:
+ pusha
+ # move 80 * 24 lines from b8050 -> b8000
+ mov $0xb8000, %edi
+ mov $0xb8050, %esi
+ mov $480, %ecx
+ rep movsl
+ # clear last line (b8780)
+ mov $0xb8780, %edi
+ xor %eax, %eax
+ mov $20, %ecx
+ rep stosl
+ popa
+ ret
+
+clearscr:
+ mov $0xb8000, %edi
+ xor %eax, %eax
+ mov $500, %ecx
+ rep stosl
+ ret
+
+ .set UART_DATA, 0x3f8
+ .set UART_LSTAT, 0x3fd
+ .set LST_TREG_EMPTY, 0x20
+
+ser_putchar:
+ push %dx
+
+ cmp $10, %al
+ jnz 0f
+ push %ax
+ mov $13, %al
+ call ser_putchar
+ pop %ax
+
+0: mov %al, %ah
+ # wait until the transmit register is empty
+ mov $UART_LSTAT, %dx
+wait: in %dx, %al
+ and $LST_TREG_EMPTY, %al
+ jz wait
+ mov $UART_DATA, %dx
+ mov %ah, %al
+ out %al, %dx
+
+ pop %dx
+ ret
+
+
+motor_off:
+ mov $0x3f2, %dx
+ in %dx, %al
+ and $0xf0, %al
+ out %al, %dx
+ ret
+
+logohack:
# copy palette
- mov $logo_pal, %si
+ mov $logo_pal, %esi
xor %cl, %cl
0: xor %eax, %eax
mov $0x3c8, %dx
movb %cl, %al
outb %al, %dx
- #### DBG
- call ser_print_num
- mov $58, %al
- call ser_putchar
- mov $32, %al
- call ser_putchar
- xor %eax, %eax
- ####
inc %dx
# red
- movb (%si), %al
- inc %si
+ movb (%esi), %al
+ inc %esi
shr $2, %al
outb %al, %dx
- #### DBG
- call ser_print_num
- mov $32, %al
- call ser_putchar
- xor %eax, %eax
- ####
# green
- movb (%si), %al
- inc %si
+ movb (%esi), %al
+ inc %esi
shr $2, %al
outb %al, %dx
- #### DBG
- call ser_print_num
- mov $32, %al
- call ser_putchar
- xor %eax, %eax
- ####
# blue
- movb (%si), %al
- inc %si
+ movb (%esi), %al
+ inc %esi
shr $2, %al
outb %al, %dx
- #### DBG
- call ser_print_num
- mov $32, %al
- call ser_putchar
- mov $10, %al
- call ser_putchar
- xor %eax, %eax
- ####
add $1, %cl
jnc 0b
# copy pixels
- pushw $0xa000
- pop %es
- xor %di, %di
- mov $logo_pix, %eax
- shr $4, %eax
- mov %ax, %ds
- xor %si, %si
- mov $16000, %ecx
- rep movsl
+ mov $sintab, %ebp
+ mov $logo_pix, %esi
+frameloop:
+ mov $0xa0000, %edi
+ movl $0, yval
+yloop:
+ movl $0, xval
+xloop:
+ # calc src scanline address -> ebx
+ xor %ecx, %ecx
+ mov yval, %ebx
+ shl $2, %ebx
+ add frameno, %ebx
+ and $0xff, %ebx
+ mov (%ebp, %ebx), %cl
+ shr $5, %ecx
- cli
- hlt
+ mov yval, %eax
+ add %ecx, %eax
+ # bounds check
+ cmp $200, %eax
+ jl 0f
+ mov $199, %eax
- # expects string pointer in ds:si
-ser_print_str:
- pusha
+0: mov %eax, %ebx
+ shl $8, %eax
+ shl $6, %ebx
+ add %eax, %ebx
-0: mov (%si), %al
- cmp $0, %al
- jz .Lend
- call ser_putchar
- inc %si
- jmp 0b
+ # calc src x offset -> eax
+ xor %ecx, %ecx
+ mov xval, %eax
+ shl $2, %eax
+ add frameno, %eax
+ and $0xff, %eax
+ mov (%ebp, %eax), %cl
+ shr $5, %ecx
-.Lend: popa
- ret
+ mov xval, %eax
+ add %ecx, %eax
+ # bounds check
+ cmp $320, %eax
+ jl 0f
+ mov $319, %eax
+0: add %eax, %ebx
+ mov (%ebx, %esi), %al
- # expects number in eax
-ser_print_num:
- # save registers
- pusha
+ mov %al, (%edi)
+ inc %edi
- movw $numbuf + 16, %si
- movb $0, (%si)
- mov $10, %ebx
-.Lconvloop:
- xor %edx, %edx
- div %ebx
- add $48, %dl
- dec %si
- mov %dl, (%si)
- cmp $0, %eax
- jnz .Lconvloop
+ incl xval
+ cmpl $320, xval
+ jnz xloop
- call ser_print_str
+ incl yval
+ cmpl $200, yval
+ jnz yloop
- # restore regs
- popa
- ret
+ incl frameno
+
+ # wait vsync
+ mov $0x3da, %dx
+0: in %dx, %al
+ and $8, %al
+ jnz 0b
+0: in %dx, %al
+ and $8, %al
+ jz 0b
+ jmp frameloop
+
+xval: .long 0
+yval: .long 0
+frameno: .long 0
numbuf: .space 16
.align 16
logo_pix:
.incbin "logo.raw"
+
+sintab:
+ .byte 127
+ .byte 130
+ .byte 133
+ .byte 136
+ .byte 139
+ .byte 143
+ .byte 146
+ .byte 149
+ .byte 152
+ .byte 155
+ .byte 158
+ .byte 161
+ .byte 164
+ .byte 167
+ .byte 170
+ .byte 173
+ .byte 176
+ .byte 179
+ .byte 182
+ .byte 184
+ .byte 187
+ .byte 190
+ .byte 193
+ .byte 195
+ .byte 198
+ .byte 200
+ .byte 203
+ .byte 205
+ .byte 208
+ .byte 210
+ .byte 213
+ .byte 215
+ .byte 217
+ .byte 219
+ .byte 221
+ .byte 224
+ .byte 226
+ .byte 228
+ .byte 229
+ .byte 231
+ .byte 233
+ .byte 235
+ .byte 236
+ .byte 238
+ .byte 239
+ .byte 241
+ .byte 242
+ .byte 244
+ .byte 245
+ .byte 246
+ .byte 247
+ .byte 248
+ .byte 249
+ .byte 250
+ .byte 251
+ .byte 251
+ .byte 252
+ .byte 253
+ .byte 253
+ .byte 254
+ .byte 254
+ .byte 254
+ .byte 254
+ .byte 254
+ .byte 255
+ .byte 254
+ .byte 254
+ .byte 254
+ .byte 254
+ .byte 254
+ .byte 253
+ .byte 253
+ .byte 252
+ .byte 251
+ .byte 251
+ .byte 250
+ .byte 249
+ .byte 248
+ .byte 247
+ .byte 246
+ .byte 245
+ .byte 244
+ .byte 242
+ .byte 241
+ .byte 239
+ .byte 238
+ .byte 236
+ .byte 235
+ .byte 233
+ .byte 231
+ .byte 229
+ .byte 228
+ .byte 226
+ .byte 224
+ .byte 221
+ .byte 219
+ .byte 217
+ .byte 215
+ .byte 213
+ .byte 210
+ .byte 208
+ .byte 205
+ .byte 203
+ .byte 200
+ .byte 198
+ .byte 195
+ .byte 193
+ .byte 190
+ .byte 187
+ .byte 184
+ .byte 182
+ .byte 179
+ .byte 176
+ .byte 173
+ .byte 170
+ .byte 167
+ .byte 164
+ .byte 161
+ .byte 158
+ .byte 155
+ .byte 152
+ .byte 149
+ .byte 146
+ .byte 143
+ .byte 139
+ .byte 136
+ .byte 133
+ .byte 130
+ .byte 127
+ .byte 124
+ .byte 121
+ .byte 118
+ .byte 115
+ .byte 111
+ .byte 108
+ .byte 105
+ .byte 102
+ .byte 99
+ .byte 96
+ .byte 93
+ .byte 90
+ .byte 87
+ .byte 84
+ .byte 81
+ .byte 78
+ .byte 75
+ .byte 72
+ .byte 70
+ .byte 67
+ .byte 64
+ .byte 61
+ .byte 59
+ .byte 56
+ .byte 54
+ .byte 51
+ .byte 49
+ .byte 46
+ .byte 44
+ .byte 41
+ .byte 39
+ .byte 37
+ .byte 35
+ .byte 33
+ .byte 30
+ .byte 28
+ .byte 26
+ .byte 25
+ .byte 23
+ .byte 21
+ .byte 19
+ .byte 18
+ .byte 16
+ .byte 15
+ .byte 13
+ .byte 12
+ .byte 10
+ .byte 9
+ .byte 8
+ .byte 7
+ .byte 6
+ .byte 5
+ .byte 4
+ .byte 3
+ .byte 3
+ .byte 2
+ .byte 1
+ .byte 1
+ .byte 0
+ .byte 0
+ .byte 0
+ .byte 0
+ .byte 0
+ .byte 0
+ .byte 0
+ .byte 0
+ .byte 0
+ .byte 0
+ .byte 0
+ .byte 1
+ .byte 1
+ .byte 2
+ .byte 3
+ .byte 3
+ .byte 4
+ .byte 5
+ .byte 6
+ .byte 7
+ .byte 8
+ .byte 9
+ .byte 10
+ .byte 12
+ .byte 13
+ .byte 15
+ .byte 16
+ .byte 18
+ .byte 19
+ .byte 21
+ .byte 23
+ .byte 25
+ .byte 26
+ .byte 28
+ .byte 30
+ .byte 33
+ .byte 35
+ .byte 37
+ .byte 39
+ .byte 41
+ .byte 44
+ .byte 46
+ .byte 49
+ .byte 51
+ .byte 54
+ .byte 56
+ .byte 59
+ .byte 61
+ .byte 64
+ .byte 67
+ .byte 70
+ .byte 72
+ .byte 75
+ .byte 78
+ .byte 81
+ .byte 84
+ .byte 87
+ .byte 90
+ .byte 93
+ .byte 96
+ .byte 99
+ .byte 102
+ .byte 105
+ .byte 108
+ .byte 111
+ .byte 115
+ .byte 118
+ .byte 121
+ .byte 124
projects / bootcensus / blobdiff