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 (file)
index 0000000..ba31d82
--- /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 (file)
index 0000000..e69de29