kolibrios-gitea/programs/network/ircc/encodings.inc

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;;                                                                 ;;
;; Copyright (C) KolibriOS team 2004-2013. All rights reserved.    ;;
;; Distributed under terms of the GNU General Public License       ;;
;;                                                                 ;;
;;   Written by CleverMouse                                        ;;
;;                                                                 ;;
;;         GNU GENERAL PUBLIC LICENSE                              ;;
;;          Version 2, June 1991                                   ;;
;;                                                                 ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;


get_next_byte:
; Load next byte from the packet, translating to cp866 if necessary
; At input esi = pointer to data, edx = limit of data
; Output is either (translated) byte in al with CF set or CF cleared.
        mov     eax, [encoding]
        jmp     [get_byte_table+eax*4]

get_byte_cp866:
        cmp     esi, edx
        jae     .nothing
        lodsb
.nothing:
        ret

get_byte_cp1251:
        cmp     esi, edx
        jae     .nothing
        lodsb
        cmp     al, 0x80
        jb      @f
        and     eax, 0x7F
        mov     al, [cp1251_table+eax]
@@:
        stc
.nothing:
        ret

get_byte_utf8:
; UTF8 decoding is slightly complicated.
; One character can occupy one or more bytes.
; The boundary in packets theoretically can be anywhere in data,
; so this procedure keeps internal state between calls and handles
; one byte at a time, looping until character is read or packet is over.
; Globally, there are two distinct tasks: decode byte sequence to unicode char
; and convert this unicode char to our base encoding (that is cp866).
; 1. Check that there are data.
        cmp     esi, edx
        jae     .nothing
; 2. Load byte.
        lodsb
        movzx   ecx, al
; 3. Bytes in an UTF8 sequence can be of any of three types.
; If most significant bit is cleared, sequence is one byte and usual ASCII char.
; First byte of a sequence must be 11xxxxxx, other bytes are 10yyyyyy.
        and     al, 0xC0
        jns     .single_byte
        jp      .first_byte
; 4. This byte is not first in UTF8 sequence.
; 4a. Check that the sequence was started. If no, it is invalid byte
; and we simply ignore it.
        cmp     [utf8_bytes_rest], 0
        jz      get_byte_utf8
; 4b. Otherwise, it is really next byte and it gives some more bits of char.
        mov     eax, [utf8_char]
        shl     eax, 6
        lea     eax, [eax+ecx-0x80]
; 4c. Decrement number of bytes rest in the sequence.
; If it goes to zero, character is read, so return it.
        dec     [utf8_bytes_rest]
        jz      .got_char
        mov     [utf8_char], eax
        jmp     get_byte_utf8
; 5. If the byte is first in UTF8 sequence, calculate the number of leading 1s
; - it equals total number of bytes in the sequence; some other bits rest for
; leading bits in the character.
.first_byte:
        mov     eax, -1
@@:
        inc     eax
        add     cl, cl
        js      @b
        mov     [utf8_bytes_rest], eax
        xchg    eax, ecx
        inc     ecx
        shr     al, cl
        mov     [utf8_char], eax
        jmp     get_byte_utf8
; 6. If the byte is ASCII char, it is the character.
.single_byte:
        xchg    eax, ecx
.got_char:
; We got the character, now abandon a possible sequence in progress.
        and     [utf8_bytes_rest], 0
; Now second task. The unicode character is in eax, and now we shall convert it
; to cp866.
        cmp     eax, 0x80
        jb      .done
; 0x410-0x43F -> 0x80-0xAF, 0x440-0x44F -> 0xE0-0xEF, 0x401 -> 0xF0, 0x451 -> 0xF1
        cmp     eax, 0x401
        jz      .YO
        cmp     eax, 0x451
        jz      .yo
        cmp     eax, 0x410
        jb      .unrecognized
        cmp     eax, 0x440
        jb      .part1
        cmp     eax, 0x450
        jae     .unrecognized
        sub     al, (0x40-0xE0) and 0xFF
        ret
.part1:
        sub     al, 0x10-0x80
.nothing:
.done:
        ret
.unrecognized:
        mov     al, '?'
        stc
        ret
.YO:
        mov     al, 0xF0
        stc
        ret
.yo:
        mov     al, 0xF1
        stc
        ret



recode_to_cp866:
        rep     movsb
        ret

recode_to_cp1251:
        xor     eax, eax
        jecxz   .nothing
  .loop:
        lodsb
        cmp     al,0x80
        jb      @f
        mov     al, [cp866_table-0x80+eax]
    @@: stosb
        loop    .loop
  .nothing:
        ret

recode_to_utf8:
        jecxz   .nothing
  .loop:
        lodsb
        cmp     al, 0x80
        jb      .single_byte
        and     eax, 0x7F
        mov     ax, [utf8_table+eax*2]
        stosw
        loop    .loop
        ret
  .single_byte:
        stosb
        loop    .loop
  .nothing:
        ret

recode:
        mov     eax, [encoding]
        jmp     [recode_proc+eax*4]



encoding        dd      UTF8
recode_proc     dd      recode_to_cp866, recode_to_cp1251, recode_to_utf8
get_byte_table  dd      get_byte_cp866, get_byte_cp1251, get_byte_utf8


cp1251_table:
  db '?','?','?','?','?','?','?','?' , '?','?','?','?','?','?','?','?' ; 8
  db '?','?','?','?','?',$F9,'?','?' , '?','?','?','?','?','?','?','?' ; 9
  db '?',$F6,$F7,'?',$FD,'?','?','?' , $F0,'?',$F2,'?','?','?','?',$F4 ; A
  db $F8,'?','?','?','?','?','?',$FA , $F1,$FC,$F3,'?','?','?','?',$F5 ; B
  db $80,$81,$82,$83,$84,$85,$86,$87 , $88,$89,$8A,$8B,$8C,$8D,$8E,$8F ; C
  db $90,$91,$92,$93,$94,$95,$96,$97 , $98,$99,$9A,$9B,$9C,$9D,$9E,$9F ; D
  db $A0,$A1,$A2,$A3,$A4,$A5,$A6,$A7 , $A8,$A9,$AA,$AB,$AC,$AD,$AE,$AF ; E
  db $E0,$E1,$E2,$E3,$E4,$E5,$E6,$E7 , $E8,$E9,$EA,$EB,$EC,$ED,$EE,$EF ; F

;    0   1   2   3   4   5   6   7     8   9   A   B   C   D   E   F

utf8_table:
        times 80h dw 0x98C3     ; default placeholder

; 0x80-0xAF -> 0x90D0-0xBFD0
repeat 0x30
        store byte 0xD0 at utf8_table+2*(%-1)
        store byte 0x90+%-1 at utf8_table+2*%-1
end repeat

; 0xE0-0xEF -> 0x80D1-0x8FD1
repeat 0x10
        store byte 0xD1 at utf8_table+2*(0xE0-0x80+%-1)
        store byte 0x80+%-1 at utf8_table+2*(0xE0-0x80+%)-1
end repeat

; 0xF0 -> 0x81D0, 0xF1 -> 0x91D1
        store dword 0x91D181D0 at utf8_table+2*(0xF0-0x80)

cp866_table:
  db $C0,$C1,$C2,$C3,$C4,$C5,$C6,$C7 , $C8,$C9,$CA,$CB,$CC,$CD,$CE,$CF ; 8
  db $D0,$D1,$D2,$D3,$D4,$D5,$D6,$D7 , $D8,$D9,$DA,$DB,$DC,$DD,$DE,$DF ; 9
  db $E0,$E1,$E2,$E3,$E4,$E5,$E6,$E7 , $E8,$E9,$EA,$EB,$EC,$ED,$EE,$EF ; A
  db '?','?','?','?','?','?','?','?' , '?','?','?','?','?','?','?','?' ; B
  db '?','?','?','?','?','?','?','?' , '?','?','?','?','?','?','?','?' ; C
  db '?','?','?','?','?','?','?','?' , '?','?','?','?','?','?','?','?' ; D
  db $F0,$F1,$F2,$F3,$F4,$F5,$F6,$F7 , $F8,$F9,$FA,$FB,$FC,$FD,$FE,$FF ; E
  db $A8,$B8,$AA,$BA,$AF,$BF,$A1,$A2 , $B0,$95,$B7,'?',$B9,$A4,'?','?' ; F

;    0   1   2   3   4   5   6   7     8   9   A   B   C   D   E   F