8086asm: clarify operands and fix stupidities

MBR code now strictly loads OS code into memory and jumps into it.

Now, I've got to consolidate my assembler code, modrm logic is
messed up.

blk/730

@@ -2,15 +2,15 @@
 
 Work in progress. Load with "750 LOAD".
 
+Mnemonics are followed by argument types. For example, MOVri,
+moves 8-bit immediate to 8-bit register.
 
+'r' = 8-bit register           'x' = 16-bit register
+'i' = immediate, size depends on other operand.
+'s' = SREG register
 
+Mnemonics that only have one signature (for example INT,) don't
+have operands letters.
 
-
-
-
-
-
-
-
-
+For jumps, it's special. 's' is SHORT, 'n' is NEAR, 'f' is FAR.
 

blk/751

@@ -3,6 +3,6 @@ CREATE BIN( 0 , : BIN(+ BIN( @ + ;
 VARIABLE L1 VARIABLE L2 VARIABLE L3 VARIABLE L4
 : AL 0 ; : CL 1 ; : DL 2 ; : BL 3 ;
 : AH 4 ; : CH 5 ; : DH 6 ; : BH 7 ;
-: AX 8 ; : CX 9 ; : DX 10 ; : BX 11 ;
-: SP 12 ; : BP 13 ; : SI 14 ; : DI 15 ;
+: AX 0 ; : CX 1 ; : DX 2 ; : BX 3 ;
+: SP 4 ; : BP 5 ; : SI 6 ; : DI 7 ;
 : ES 0 ; : CS 1 ; : SS 2 ; : DS 3 ;

blk/752

@@ -4,5 +4,3 @@
 ;
 : PC H@ ORG @ - BIN( @ + ;
 : A, C, ;
-( dst8 src8 -- modrm )
-: MODRMrr 0x7 AND 3 LSHIFT SWAP 0x7 AND OR 0xc0 OR ;

blk/753

@@ -1,11 +1,12 @@
+: OP1 CREATE C, DOES> C@ A, ;
+0xac OP1 LODSB,      0xfa OP1 CLI,       0xfb OP1 STI,
+0xf4 OP1 HLT,        0xfc OP1 CLD,       0xfd OP1 STD,
+( no argument, jumps with abs addrs are special )
+0xeb OP1 JMPs,       0xe9 OP1 JMPn,      0x74 OP1 JZ,
 : MOVri, SWAP 0xb0 OR A, A, ;
-: MOVrI, SWAP 0xb0 OR A, SPLITB A, A, ;
-: MOVsx, 0x8e A, SWAP MODRMrr A, ;
+: MOVxi, SWAP 0xb8 OR A, SPLITB A, A, ;
+: MOVsx, 0x8e A, SWAP 3 LSHIFT OR 0xc0 OR A, ;
 : INT, 0xcd A, A, ;
-( no argument, flow ops are special )
-: JMP8, 0xeb A, ; : JMP16, 0xe9 A, ; : JZ, 0x74 A, ;
-: LODSB, 0xac A, ; : CLI, 0xfa A, ; : HLT, 0xf4 A, ;
-: STI, 0xfb A, ;
-: ORrr, 0x08 A, MODRMrr A, ;
-: XORxx, 0x31 A, MODRMrr A, ;
-: CLD, 0xfc A, ; : STD, 0xfd A, ;
+: JMPr, 0xff A, 7 AND 0xe0 OR A, ;
+: OPrr CREATE C, DOES> C@ A, 3 LSHIFT OR 0xc0 OR A, ;
+0x31 OPrr XORxx,     0x08 OPrr ORrr,

blk/755

@@ -1,4 +1,4 @@
-: FWR8 BSET 0 A, ;
+: FWRs BSET 0 A, ;
 : FSET @ THEN, ;
 ( : BREAK, FJR, 0x8000 OR ;
 : BREAK?, DUP 0x8000 AND IF

blk/811

@@ -1,14 +1,10 @@
 H@ ORG ! 0x7c00 BIN( ! ( BIOS loads boot bin at 0x7c00 )
-JMP8, L1 FWR8 ( start )
+JMPs, L1 FWRs ( start )
 ORG @ 0x25 + HERE ! ( bypass BPB )
-L2 BSET ( msg ) ," Hello, World!" 0 A,
 L1 FSET ( start )
-CLI, CLD, AX AX XORxx, DS AX MOVsx, STI,
-AH 0 MOVri, AL 2 MOVri, ( 80x25 BW video mode ) 0x10 INT,
-SI L2 @ ( msg ) MOVrI, AH 0x0e MOVri, ( print char )
-L1 BSET ( loop ) LODSB, AL AL ORrr, ( end of str? )
-JZ, L2 FWR8 ( next ) 0x10 INT, ( print char )
-JMP8, L1 ( loop ) BWR
-L2 FSET ( next ) AH 0 MOVri, 0x16 INT, ( read kbd )
-AH 0x0e MOVri, 0x10 INT, ( spit read char ) HLT, ( done )
+CLI, CLD, AX AX XORxx, DS AX MOVsx, ES AX MOVsx,
+SS AX MOVsx, SP 0xffff MOVxi, STI,
+AH 2 MOVri, DX 0 MOVxi, CH 0 MOVri, CL 2 MOVri, AL 1 MOVri,
+BX 0x8000 MOVxi, 0x13 INT, ( read 2nd sector of boot floppy )
+BX JMPr,
 ORG @ 0x1fe + HERE ! 0x55 A, 0xaa A,

blk/812

@@ -0,0 +1,10 @@
+H@ ORG ! 0x8000 BIN( !
+JMPs, L1 FWRs ( start )
+L2 ( msg ) BSET ," Hello World!" 0 A,
+L1 FSET ( start )
+SI L2 @ ( msg ) MOVxi, AH 0x0e MOVri, ( print char )
+L1 BSET ( loop ) LODSB, AL AL ORrr, ( end of str? )
+JZ, L2 FWRs ( next ) 0x10 INT, ( print char )
+JMPs, L1 ( loop ) BWR
+L2 FSET ( next ) AH 0 MOVri, 0x16 INT, ( read kbd )
+AH 0x0e MOVri, 0x10 INT, ( spit read char ) HLT, ( done )

emul/Makefile

@@ -44,4 +44,4 @@ unpack:
 
 .PHONY: clean
 clean:
-	rm -f $(TARGETS) emul.o *-bin.h blkfs
+	rm -f $(TARGETS) emul.o *-bin.h blkfs libz80/libz80.o

recipes/pcat/Makefile

@@ -1,16 +1,26 @@
-TARGET = boot.bin
+TARGET = disk.bin
 BASEDIR = ../..
 EDIR = $(BASEDIR)/emul
 STAGE = $(EDIR)/stage
 
 .PHONY: all
 all: $(TARGET) 
-$(TARGET): xcomp.fs $(STAGE)
+mbr.bin: mbr.fs $(STAGE)
+	cat mbr.fs | $(STAGE) > $@
+
+os.bin: xcomp.fs $(STAGE)
 	cat xcomp.fs | $(STAGE) > $@
 
+disk.bin: mbr.bin os.bin
+	cat mbr.bin os.bin > $@
+
 $(STAGE):
 	$(MAKE) -C $(EDIR) stage
 
 .PHONY: emul
 emul: $(TARGET)
 	qemu-system-i386 -fda $(TARGET)
+
+.PHONY: clean
+clean:
+	rm *.bin

recipes/pcat/mbr.fs

@@ -0,0 +1,4 @@
+750 LOAD
+811 LOAD
+ORG @ 256 /MOD 2 PC! 2 PC!
+H@ 256 /MOD 2 PC! 2 PC!

recipes/pcat/xcomp.fs

@@ -1,4 +1,4 @@
 750 LOAD
-811 LOAD
+812 LOAD
 ORG @ 256 /MOD 2 PC! 2 PC!
 H@ 256 /MOD 2 PC! 2 PC!