From: Alan Cox <alan@linux.intel.com>
Date: Sun, 1 Feb 2015 21:31:01 +0000 (+0000)
Subject: 8086: just committing these unfinished so I don't forget to add them
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=af1f960d1b4e45487e0e58bc57d080da1e1507f9;p=FUZIX.git

8086: just committing these unfinished so I don't forget to add them
---

diff --git a/Kernel/lowlevel-8086.S b/Kernel/lowlevel-8086.S
new file mode 100644
index 00000000..ba31d828
--- /dev/null
+++ b/Kernel/lowlevel-8086.S
@@ -0,0 +1,149 @@
+
+		.code
+
+;
+;	FIXME: udata will really be a pointer
+;
+unix_syscall_entry:
+	push ds
+	push es
+
+	push bp
+	mov bp, sp
+	mov bx, cs:_kernel_ds	; Load our DS
+	mov ds, bx
+	mov es, bx
+
+	; We are now referencing the kernel except for the stack
+	; and that has our arguments on it with 6 bytes of trap
+	; return info before it and two segment registers we
+	; added. bp will reference ss: so we can now stash away our
+	; arguments in peace
+
+	mov bx, _udataptr
+	mov U_DATA__U_CALLNO[bx], ax
+	mov ax, 10[bp]
+	mov U_DATA__U_ARGN[bx], ax
+	mov ax, 12[bp]
+	mov U_DATA__U_ARGN1[bx], ax
+	mov ax, 14[bp]
+	mov U_DATA__U_ARGN2[bx], ax
+	mov ax, 16[bp]
+	mov U_DATA__U_ARGN3[bx], ax
+
+	;
+	; Time to stack switch (we need SP for brk() even though the
+	; entry/exit code has no need of it and can use bp
+	;
+	mov ax, sp
+	mov U_DATA__U_SYSCALL_SP[bx], ax
+	; save SS anyway - will be useful if we ever do multi-segment
+	; binaries
+	mov ax, ss
+	mov U_DATA__U_SYSCALL_SS[bx], ax
+
+	;
+	; Stack switch. Load sp the instruction after ss. Doesn't matter
+	; currently as IRQs are off, but may if this changes
+	;
+	mov ax, ds
+	mov ss, ax
+	mov sp, U_DATA__U_KSTACK[bx]
+
+	mov byte _kernel_flag, #1
+
+	sti	
+	call _unix_syscall
+	cli
+
+	mov byte _kernel_flag, #0
+;
+;	SIGNALS TODO
+;
+
+	;
+	; We effective return a 32bit ulong to bcc half of which is return
+	; and error
+	;
+	mov dx, U_DATA__U_ERROR[bx]
+	mov ax, U_DATA__U_RETVAL[bx]
+
+	;
+	; Stack back
+	;
+	mov bx, U_DATA__U_SYSCALL_SS[bx]
+	mov ss, bx
+	mov sp, bp
+	pop es
+	pop ds
+	iret
+
+;
+;	AX is the address to jump to
+;
+_doexec:
+	cli
+	mov byte _kernel_flag, #0
+	mov bx, _udata_ptr
+	;
+	; Stack the new CS
+	;
+	mov dx, U_DATA__U_CS[bx], dx
+	push dx
+	push ax			; 32bit target address
+	;
+	; Load the initial stack
+	;
+	mov dx, U_DATA__U_SIP[bx]
+	mov sp, dx
+	mov dx, U_DATA__U_SS[bx], dx
+	mov ss, dx
+	;
+	; Load the data segment into ES
+	;
+	mov dx, U_DATA__U_DS[bx], dx
+	mov es, dx
+	;
+	; Just ES and DS left to go
+	;
+	mov byte U_DATA__U_INSYS, #0
+	;
+	; And go
+	;
+	mov ds, dx
+	mov ax, #0
+	mov bx, ax
+	mov cx, ax
+	mov dx, ax
+	mov si, ax
+	mov di, ax
+	mov bp, ax
+	sti			; will occur after the retf completes
+	retf
+
+interrupt_handler:
+	/* TODO */
+	iret
+
+trap_signal:
+	mov bx, _udata_ptr
+	mov U_DATA__U_PTAB[bx], ax
+	jmp _ssig
+
+outstring:
+outstringhex:
+outax:
+outcharhex:	
+	ret
+
+_di:
+	pushf
+	pop ax
+	cli
+	ret
+
+_irqrestore:
+	push ax
+	popf
+	ret
+	
\ No newline at end of file
diff --git a/Kernel/usermem_std-8086.S b/Kernel/usermem_std-8086.S
new file mode 100644
index 00000000..e69de29b