cpuid.asm

section .bss ; $Revision: 1.6 $
vendor_id   resd    12	;reserve 12 bytes of memory
version     resd    4
features    resd    4
i           resd    4
curfeat     resd    4

section .text
global _start			;must be declared for linker (ld)
names	db	'FPU  VME  DE   PSE  TSC  MSR  PAE  MCE  CX8  APIC RESV SEP  MTRR PGE  MCA  CMOV PAT  PSE3 PSN  CLFS RESV DS   ACPI MMX  FXSR SSE  SSE2 SS   HTT  TM   RESV PBE '
newline db 0x0a

_start:					;tell linker entry point

mov eax,0
cpuid; get the vendor name
mov [vendor_id],ebx ; store the result in vendor_id
mov [vendor_id+4],edx
mov [vendor_id+8],ecx

;syscall(SYS_write, 0, str, sizeof(str)-1)
mov edx,12		;message length
mov ecx,vendor_id	;message to write (msg is a pointer to the start of the string)
mov ebx,1	;file descriptor (stdout)
mov eax,4	;system call number (sys_write)
int 0x80	;call kernel - i.e. run the system call

; Write out newline (\n)
mov edx, 1
mov ecx, newline
mov ebx,1
mov eax,4
int 0x80

mov eax,1 
cpuid; Get Features
mov [version],eax
mov [features],edx

;Equivalent of for(i = 8; i != 0; i++)
mov	eax,00000001h
mov	[curfeat],eax
mov     eax,-1
mov     [i],eax
.loop:
;;--i

mov     eax,[i]
inc eax; (i++)
cmp eax,31
jz .quitloop   ;quit loop if reached limit
mov [i],eax    ;put updated value on stack

;get current feature
mov ebx,[curfeat]
;test for feature - if feature exists ebx is non zero
and ebx,[features]
;left shift to test for next feature (will be used in next iteration of loop)
mov eax,[curfeat]
shl eax,1
mov [curfeat],eax

;jump if feaure not exist
cmp ebx,0
jz .loop ;check if zero flag is set - if it is it means that the feature didn't exist so we don't want to print anything out
;;otherwise this feature must exist lets print it out...
        mov     eax,[i] ;get value from stack           0x080480bf
        mov     edx,5   ;message length
        mov     ecx,names     ;message to write (msg is a pointer to the start of the string
times 5	add	ecx,eax
	
        mov     ebx,1   ;file descriptor (stdout)
        mov     eax,4   ;system call number (sys_write) 0x080480b7
        int     0x80    ;call kernel                    0x080480be

	jmp .loop ; unconditional jump
;}
.quitloop:

; Write out newline (\n)
mov edx, 1
mov ecx, newline
mov ebx,1
mov eax,4
int 0x80

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
mov	eax,1	;system call number (sys_exit)
mov	ebx,0	;exit status 0 (if not used is 1 as set before) "echo $?" to check
int	0x80	;call kernel