duskos

commit d27c3be65ff94d7382ee81f21e05142a3e89e4ad
parent 0a6dbc7a465cf432521d1702fe9b039bb64d7bae
Author: Virgil Dupras <hsoft@hardcoded.net>
Date:   Wed, 20 Jul 2022 21:10:27 -0400

Bare metal on PC: first tiny step

Diffstat:
M
.gitignore
 | 
1
+
M
Makefile
 | 
7
+++++++
A
buildpc.fs
 | 
4
++++
M
dusk.asm
 | 
9
+++++++++
M
fs/asm/i386.fs
 | 
5
++++-
A
fs/xcomp/pc/mbr.fs
 | 
10
++++++++++

6 files changed, 35 insertions(+), 1 deletion(-)
diff --git a/.gitignore b/.gitignore
@@ -1,4 +1,5 @@
 /dusk
 /fatfs
 /boot.fs
+/pc.bin
 *.o
diff --git a/Makefile b/Makefile
@@ -20,6 +20,13 @@ fatfs: $(ALLSRCS)
 	mformat -M 512 -d 1 -i $@ ::
 	mcopy -sQ -i $@ fs/* ::
 
+pc.bin: dusk
+	./dusk < buildpc.fs 2> $@
+
+.PHONY: pcrun
+pcrun: pc.bin
+	qemu-system-i386 -drive file=pc.bin,if=floppy,format=raw
+
 .PHONY: run
 run: dusk
 	stty -icanon -echo; ./dusk ; stty icanon echo
diff --git a/buildpc.fs b/buildpc.fs
@@ -0,0 +1,4 @@
+: spit ( a u -- ) >r begin c@+ stderr next ;
+f<< /xcomp/pc/mbr.fs
+
+ORG $200 spit bye
diff --git a/dusk.asm b/dusk.asm
@@ -230,6 +230,15 @@ defword '(emit)', 6, word__emit
 defword 'emit', 4, word_emit
 	sysalias emit
 
+defword 'stderr', 6, word_stderr
+	mov eax, SYSCALL_WRITE
+	mov ebx, 2				; stderr
+	mov ecx, ebp			; buffer: top of PS, little endian
+	mov edx, 1				; len
+	int 0x80
+	pspop eax
+	ret
+
 defword 'key', 3, word_key
 	pspush 0
 	mov eax, SYSCALL_READ
diff --git a/fs/asm/i386.fs b/fs/asm/i386.fs
@@ -24,6 +24,7 @@ SZ32 value opsz
 0 value imm \ value of current immediate, if set
 0 value disp \ displacement value
 0 value sib \ value of the SIB byte
+0 value ORG \ base address for jmp, and call, rel32 computing
 
 \ Utilities
 : asm$ SZ32 to opsz 1 to opdirec 3 to opmod -1 to opreg -1 to oprm 0 to imm? ;
@@ -149,7 +150,7 @@ $840f op jz,        $850f op jnz,
 \ the "opreg" for the modrm version.
 : op ( opcode -- ) doer , does> @ ( rel32? opcode -- )
   opreg 0< if ( rel32 opcode )
-    c, here - 4 - , asm$
+    c, here - ORG + 4 - , asm$
   else \ ( opcode )
     8 rshift opreg! $ff opmodrm,
   then ;
@@ -208,3 +209,5 @@ $58 op pop,        $50 op _push,
     else $c7 c, 0 opreg! msd, imm, asm$ then
   else $88 opmodrm, then ;
 
+\ INT is special
+: int, ( n -- ) $cd c, c, ;
diff --git a/fs/xcomp/pc/mbr.fs b/fs/xcomp/pc/mbr.fs
@@ -0,0 +1,10 @@
+\ x86 bootloader
+?f<< /asm/i386.fs
+
+here to ORG here $200 0 fill
+$26 jmp, \ bypass BPB
+$21 allot
+ax $0e58 i) mov,
+$10 int,
+here jmp,
+$55 ORG $1fe + c!+ $aa swap c!