; This contains the CPU-dependant variants of some routines.
; (C) 2005 Andreas Rumpf
; This code was inspired by the Freepascal compiler's sources
; All routines here have the _cdecl calling convention because
; that is the only convention any C compiler supports.

\python{
# as usual I use my own preprocessor :-)
import os

def c(name): 
  if os.name == 'posix':
    return name
  else:
    return "_" + name
}

segment code

global \c{cpu_inc_locked}
global \c{cpu_dec_locked}
global \c{cpu_lock}
global \c{cpu_unlock}

\c{cpu_dec_locked}:  
          push ebp 
          mov ebp,esp 
          mov eax,[ebp+8] ; first parameter to function 
          lock dec dword [eax]
          setz      al
          mov esp,ebp 
          pop ebp 
          ret

\c{cpu_inc_locked}:
          push ebp 
          mov ebp,esp 
          mov eax,[ebp+8] ; first parameter to function 
          lock inc dword [eax]
          mov esp,ebp 
          pop ebp 
          ret

; This code uses the highest bit of the RC to indicate that the RC is
; locked (spinlock).
\c{cpu_lock}
          push ebp 
          mov ebp, esp 
          mov eax, [ebp+8]     ; first parameter to function 
          mov edx, [eax]       ; load RC
          or  edx, 0x80000000  ; set highest bit
     spin:
          xchg [eax], edx      ; atomic instruction!
          pause                ; wait a few cycles
          and edx, 0x80000000  ; mask highest bit
          jnz spin
          mov esp, ebp
          pop ebp
          ret

\c{cpu_unlock}
          push ebp            
          mov ebp, esp 
          mov eax, [ebp+8]     ; first parameter to function 
          mov edx, [eax]       ; load RC
          and edx, 0x7FFFFFFF  ; unset highest bit
          xchg [eax], edx      ; atomic instruction!
          mov esp, ebp
          pop ebp
          ret