基本用法

    mov  edi, (80*2 + 0) * 2   ;屏幕第10行，第0列
    mov  ah,  0Ch               ;0000：黑底  1100：红字
    mov  al,  'z'
    mov  [gs:edi], ax

DspStr

DspStr:
    push    ebp
    mov ebp, esp

    mov esi, [ebp + 8]  ; pszInfo
    mov edi, [disp_pos]
    mov ah, 0Fh
.1:
    lodsb
    test    al, al
    jz  .2
    cmp al, 0Ah ; 是回车吗?
    jnz .3
    push    eax
    mov eax, edi
    mov bl, 160
    div bl
    and eax, 0FFh
    inc eax
    mov bl, 160
    mul bl
    mov edi, eax
    pop eax
    jmp .1
.3:
    mov [gs:edi], ax
    add edi, 2
    jmp .1

.2:
    mov [disp_pos], edi

    pop ebp
    ret

lodsb将字符串中的字符取到al中；
test al, al
字符串结束符'\0'的ascii值是0，此时test控制为0，jz成立；

DspStrFixPos

DspStrFixPos:
    push    ebp
    mov ebp, esp
    
    mov ebx, [ebp + 8]  ; pszLine
    mov [disp_pos_2], ebx

    mov esi, [ebp + 12] ; pszInfo
    mov edi, ebx;[disp_pos_2]
    mov ah, 0Fh
.1:
    lodsb
    test    al, al
    jz  .2
    cmp al, 0Ah ; 是回车吗?
    jnz .3
    push    eax
    mov eax, edi
    mov bl, 160
    div bl
    and eax, 0FFh
    inc eax
    mov bl, 160
    mul bl
    mov edi, eax
    pop eax
    jmp .1
.3:
    mov [gs:edi], ax
    add edi, 2
    jmp .1

.2:
    ;mov    [disp_pos_2], edi

    pop ebp
    ret

调用：

PUBLIC void cstart(){
    //DspStrFixPos((80*20+0)*2, str0);
    DspStrFixPos((80*24+0)*2, str1);
    
    //sprintf(buf, "hello os printk year is %d, month is %d, day is %d\n", 2020, 11, 8);
    //DspStrFixPos(12, buf);
    //sprintf(buf, "hello os sprintf, time is %d:%d\n", 14, 38);
    //DspStrFixPos(13, buf);
}

效果：