Espresso/arch/x86/cpuid_asm.asm

global get_cpu_brand_string

section .text

; void get_cpu_brand_string(char* buffer)

get_cpu_brand_string:
    pushad                      ; Save registers

    mov edi, eax               ; EAX = pointer to output buffer

    mov eax, 0x80000000
    cpuid
    cmp eax, 0x80000004
    jb .not_supported

    mov esi, edi               ; Buffer pointer → ESI

    ; ---- CPUID leaf 0x80000002 ----
    mov eax, 0x80000002
    cpuid
    mov [esi],     eax
    mov [esi+4],   ebx
    mov [esi+8],   ecx
    mov [esi+12],  edx

    ; ---- CPUID leaf 0x80000003 ----
    mov eax, 0x80000003
    cpuid
    mov [esi+16],  eax
    mov [esi+20],  ebx
    mov [esi+24],  ecx
    mov [esi+28],  edx

    ; ---- CPUID leaf 0x80000004 ----
    mov eax, 0x80000004
    cpuid
    mov [esi+32],  eax
    mov [esi+36],  ebx
    mov [esi+40],  ecx
    mov [esi+44],  edx

    mov byte [esi+48], 0        ; Null terminator

    jmp .done

.not_supported:
    mov byte [edi], 0

.done:
    popad
    ret