X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?a=blobdiff_plain;f=src%2Fboot%2Fboot2.s;h=0f2bbf83e235ce5358188b1ab259b37b77e55bd1;hb=c3e1be53f1269385b7f2b64442b85747e20b2412;hp=86ee611d309a754d3b773eb05e1f68e0d79b68c4;hpb=e552b31989dbb36f780428332be1b4958d26a37b;p=bootcensus

diff --git a/src/boot/boot2.s b/src/boot/boot2.s
index 86ee611..0f2bbf8 100644
--- a/src/boot/boot2.s
+++ b/src/boot/boot2.s
@@ -1,10 +1,323 @@
+# 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 print_num
-	.extern ser_putchar
+	.set drive_number, 0x7bec
+	# reset floppy drive
+	xor %ax, %ax
+	movb drive_number, %dl
+	int $0x13
+
+	# 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
+
+	mov $0x18, %ax
+	ltr %ax
+
+	#movb $10, %al
+	#call ser_putchar
+
+	call clearscr
+
+	mov $hello, %esi
+	call putstr
+
+	# enable A20 line
+	call enable_a20
+
+	cli
+	hlt
+
+hello: .asciz "Switched to 32bit\n"
+
+	.align 4
+gdt_lim: .word 31
+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
+	# 3: dummy TSS - base:tss, lim:103, type avail 32bit TSS, byte-granular
+	.short 103
+	.short tss
+	.short 0x8900
+	.short 0
+
+
+	.align 8
+idt:	.space 104
+	# trap gate 13: general protection fault
+	.short prot_fault
+	.short 0x8
+	# type: trap, present, default
+	.short 0x8f00
+	.short 0
+
+	.align 4
+tss:	.space 104
+
+gpf_msg: .asciz "GPF "
+
+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"
+foo_msg: .asciz "Foo\n"
+
+enable_a20:
+	mov $foo_msg, %esi
+	call putstr
+	jmp .La20done
+
+	call test_a20
+	jnc .La20done
+	call enable_a20_kbd
+	call test_a20
+	jnc .La20done
+	call enable_a20_fast
+	call test_a20
+	jnc .La20done
+	# keep trying ... we can't do anything useful without A20 anyway
+	jmp enable_a20
+.La20done:
+	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
+
+ena20_fast_msg: .asciz "Attempting fast A20 enable\n"
+
+enable_a20_fast:
+	mov $ena20_fast_msg, %esi
+	call putstr
+
+	in $0x92, %al
+	or $2, %al
+	out %al, $0x92
+	ret
+
+	.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
+
+ena20_kbd_msg: .asciz "Attempting KBD A20 enable\n"
+
+	# enable A20 line through the keyboard controller
+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
+
+	# 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
+.Lconvloop:
+	xor %edx, %edx
+	div %ebx
+	add $48, %dl
+	dec %esi
+	mov %dl, (%esi)
+	cmp $0, %eax
+	jnz .Lconvloop
+
+	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
+.Lwait:	in %dx, %al
+	and $LST_TREG_EMPTY, %al
+	jz .Lwait
+	mov $UART_DATA, %dx
+	mov %ah, %al
+	out %al, %dx
+
+	pop %dx
+	ret
 
+
+	.code16
+logohack:
 	mov $0x13, %ax
 	int $0x10
 
@@ -16,68 +329,132 @@
 	mov $0x3c8, %dx
 	movb %cl, %al
 	outb %al, %dx
-	#DBG
-	call 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
 	shr $2, %al
 	outb %al, %dx
-	#DBG
-	call print_num
-	mov $32, %al
-	call ser_putchar
-	xor %eax, %eax
-	####
 	# green
 	movb (%si), %al
 	inc %si
 	shr $2, %al
 	outb %al, %dx
-	#DBG
-	call print_num
-	mov $32, %al
-	call ser_putchar
-	xor %eax, %eax
-	####
 	# blue
 	movb (%si), %al
 	inc %si
 	shr $2, %al
 	outb %al, %dx
-	#DBG
-	call print_num
-	mov $32, %al
-	call ser_putchar
-	mov $13, %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 %ax, %ds
+	mov %ax, %gs
+	#mov $16000, %ecx
+	#rep movsl
 
-	cli
-	hlt
+	mov $sintab, %eax
+	shr $4, %eax
+	mov %ax, %fs
+
+.Lframeloop:
+	xor %di, %di
+
+	movw $0, yval
+.Lyloop:
+	movw $0, xval
+.Lxloop:
+	# calc src scanline address -> bx
+	mov yval, %bx
+	shl $2, %bx
+	add frameno, %bx
+	xor %bh, %bh
+	mov %fs:(%bx), %cl
+	xor %ch, %ch
+	shr $5, %cx
+
+	mov yval, %ax
+	add %cx, %ax
+	# bounds check
+	cmp $200, %ax
+	jl 0f
+	mov $199, %ax
+
+0:	mov %ax, %bx
+	shl $8, %ax
+	shl $6, %bx
+	add %ax, %bx
+
+	# calc src x offset -> si
+	mov xval, %ax
+	shl $2, %ax
+	add frameno, %ax
+	xor %ah, %ah
+	mov %ax, %si
+	mov %fs:(%si), %cl
+	xor %ch, %ch
+	shr $5, %cx
+
+	mov xval, %ax
+	add %cx, %ax
+	# bounds check
+	cmp $320, %ax
+	jl 0f
+	mov $319, %ax
+
+0:	mov %ax, %si
+
+	mov %gs:(%bx, %si), %al
+
+	mov %al, %es:(%di)
+	inc %di
+
+	incw xval
+	cmpw $320, xval
+	jnz .Lxloop
+
+	incw yval
+	cmpw $200, yval
+	jnz .Lyloop
+
+	incw 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 .Lframeloop
+
+xval: .word 0
+yval: .word 0
+frameno: .word 0
+
+	# expects string pointer in ds:si
+ser_print_str:
+	pusha
+
+0:	mov (%si), %al
+	cmp $0, %al
+	jz .Lend
+	call ser_putchar
+	inc %si
+	jmp 0b
+
+.Lend:	popa
+	ret
+
+
+
+numbuf: .space 16
 
 logo_pal:
 	.incbin "logo.pal"
@@ -85,3 +462,261 @@ 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