+# pcboot - bootable PC demo/game kernel
+# Copyright (C) 2018-2019 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/>.
+
.code32
- .section .startup
+ .section .startup,"ax"
.extern _bss_start
.extern _bss_end
+ .extern pcboot_main
+ .extern wait_vsync
+ .extern kb_getkey
+
+ .equ STACKTOP,0x80000
+ # move the stack to the top of the conventional memory
+ cli
+ movl $STACKTOP, %esp
+ # push a 0 ret-addr to terminate gdb backtraces
+ pushl $0
+
+ # zero the BSS section
xor %eax, %eax
- mov _bss_start, %edi
- mov _bss_size, %ecx
+ mov $_bss_start, %edi
+ mov $_bss_size, %ecx
+ cmp $0, %ecx
+ jz skip_bss_zero
shr $4, %ecx
rep stosl
+skip_bss_zero:
+
+ call pcboot_main
+ # pcboot_main never returns
+0: cli
+ hlt
+ jmp 0b
+
+ # this is called once after memory init, to move the protected mode
+ # stack to the top of usable memory, to avoid interference from 16bit
+ # programs (as much as possible)
+ .global move_stack
+move_stack:
+ # calculate the currently used lowest address of the stack (rounded
+ # down to 4-byte alignment), to see where to start copying
+ mov %esp, %esi
+ and $0xfffffffc, %esi
+ # calculate the size we need to copy
+ mov $STACKTOP, %ecx
+ sub %esi, %ecx
+ # load the destination address to edi
+ mov 4(%esp), %edi
+ sub %ecx, %edi
+ # size in longwords
+ shr $2, %ecx
+
+ # change esp to the new stack
+ mov $STACKTOP, %ecx
+ sub %esp, %ecx
+ mov 4(%esp), %eax
+ mov %eax, %esp
+ sub %ecx, %esp
+
+ rep movsd
+ ret
+
+ .global logohack
+logohack:
+ pusha
+
+ # copy palette
+ mov $logo_pal, %esi
+ xor %cl, %cl
+
+0: xor %eax, %eax
+ mov $0x3c8, %dx
+ movb %cl, %al
+ outb %al, %dx
+ inc %dx
+ # red
+ movb (%esi), %al
+ inc %esi
+ shr $2, %al
+ outb %al, %dx
+ # green
+ movb (%esi), %al
+ inc %esi
+ shr $2, %al
+ outb %al, %dx
+ # blue
+ movb (%esi), %al
+ inc %esi
+ shr $2, %al
+ outb %al, %dx
+ add $1, %cl
+ jnc 0b
+
+ # copy pixels
+ 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
+
+ mov yval, %eax
+ add %ecx, %eax
+ # bounds check
+ cmp $200, %eax
+ jl 0f
+ mov $199, %eax
+
+0: mov %eax, %ebx
+ shl $8, %eax
+ shl $6, %ebx
+ add %eax, %ebx
+
+ # 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
+
+ mov xval, %eax
+ add %ecx, %eax
+ # bounds check
+ cmp $320, %eax
+ jl 0f
+ mov $319, %eax
+
+0: add %eax, %ebx
+ mov (%ebx, %esi), %al
+
+ mov %al, (%edi)
+ inc %edi
+
+ incl xval
+ cmpl $320, xval
+ jnz xloop
+
+ incl yval
+ cmpl $200, yval
+ jnz yloop
+
+ incl frameno
+
+ call wait_vsync
+
+ # check for escape keypress
+ call kb_getkey
+ cmp $27, %eax
+ jz 0f
+
+ jmp frameloop
+
+0: popa
+ ret
+
+xval: .long 0
+yval: .long 0
+frameno: .long 0
+
+logo_pal:
+ .incbin "logo.pal"
+
+ .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