kvisc/ka/usr/cmd/dir.k

; The OS/K Team licenses this file to you under the MIT license.
; See the LICENSE file in the project root for more information.

NAME_MAX := 256

builtins.dir:
    push rbp
    mov rbp, rsp

    push r12
    mov r12, zero        # no. of files found

    mov rcx, STRLEN_MAX
    mov rdx, .dirmsg
    prns.rep.nz rdx

.dirmsg = "Directory of C:\\\n\n"

.first:
    mov rax, Sys.FindFirst
    mov ax0, .buf
    mov ax1, NAME_MAX
    trap 0

    jmp .list

.next:
    mov rax, Sys.FindNext
    mov ax0, .buf
    mov ax1, NAME_MAX
    trap 0

.list:
    jmp.axz .end

    ; found something
    add r12, r12, 1

    ; separate extension from file name
    mov rcx, NAME_MAX
    mov rsi, .buf
    mov rdi, rsi
    scasb.rep.nz rsi, '.'

    ; print file name
    sub rcx, rsi, rdi
    prns.rep rdi

    ; calculate where to put extension
    sub rdi, rsi, .buf
    sub rdi, rdi, 1

.ext_pad:
    ; print at least 11 non-space characters before extension
    b.ae rdi, 11, .print_ext
    prn ' '
    add rdi, rdi, 1
    jmp .ext_pad

.print_ext:
    ; here we print at least 4 characters excluding '.'
    mov rcx, 4
    prn ' '

    cmp b[rsi], '.'
    add.z rsi, rsi, 1

.print_ext.1:
    b.z b[rsi], 0, .print_ext.2

    ; print and decrease rcx, unless it's already 0
    mov rbx, b[rsi]
    prn rbx
    add rsi, rsi, 1
    sub.cxnz rcx, rcx, 1

    jmp .print_ext.1

.print_ext.2:
    ; did we print at least 4 bytes?
    jmp.cxz .print_bytes    ; yes, carry on

    prn.rep ' '

.print_bytes:
    ; print file size in bytes
    prn ' '
    prn ' '
    prn ' '

    shr rax, rdx, 10
    and rdx, rdx, 1023

    push rdx
    push rax
    call printf, .bytesstr
    add rsp, rsp, 16

.bytesstr = "%d kilobytes + %d bytes"

.prepare_next:
    ; go find next entry
    prn 10
    jmp .next

.end:
    push r12
    call printf, .endstr1
    add rsp, rsp, 8

    call print, .endstr2

    pop r12

    leave
    ret

.buf = [256]
.endstr1 = "             %d file(s)\n"
.endstr2 = "             0 dir(s)\n"