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; inffasx64.asm is a hand tuned assembler version of inffast.c - fast decoding
; version for AMD64 on Windows using Microsoft C compiler
;
; inffasx64.asm is automatically convert from AMD64 portion of inffas86.c
; inffasx64.asm is called by inffas8664.c, which contain more info.


; to compile this file, I use option
;   ml64.exe /Flinffasx64 /c /Zi inffasx64.asm
;   with Microsoft Macro Assembler (x64) for AMD64
;
;   ml64.exe is given with Visual Studio 2005, Windows 2003 server DDK
;
;   (you can get Windows 2003 server DDK with ml64 and cl.exe for AMD64 from 
;      http://www.microsoft.com/whdc/devtools/ddk/default.mspx for low price)
;

.code
inffas8664fnc PROC

; see http://weblogs.asp.net/oldnewthing/archive/2004/01/14/58579.aspx and
; http://msdn.microsoft.com/library/en-us/kmarch/hh/kmarch/64bitAMD_8e951dd2-ee77-4728-8702-55ce4b5dd24a.xml.asp
;
; All registers must be preserved across the call, except for
;   rax, rcx, rdx, r8, r-9, r10, and r11, which are scratch.


        mov [rsp-8],rsi
        mov [rsp-16],rdi
        mov [rsp-24],r12
        mov [rsp-32],r13
        mov [rsp-40],r14
        mov [rsp-48],r15
        mov [rsp-56],rbx

        mov rax,rcx

        mov     [rax+8], rbp       ; /* save regs rbp and rsp */
        mov     [rax], rsp

        mov     rsp, rax          ; /* make rsp point to &ar */

        mov     rsi, [rsp+16]      ; /* rsi  = in */
        mov     rdi, [rsp+32]      ; /* rdi  = out */
        mov     r9, [rsp+24]       ; /* r9   = last */
        mov     r10, [rsp+48]      ; /* r10  = end */
        mov     rbp, [rsp+64]      ; /* rbp  = lcode */
        mov     r11, [rsp+72]      ; /* r11  = dcode */
        mov     rdx, [rsp+80]      ; /* rdx  = hold */
        mov     ebx, [rsp+88]      ; /* ebx  = bits */
        mov     r12d, [rsp+100]    ; /* r12d = lmask */
        mov     r13d, [rsp+104]    ; /* r13d = dmask */
                                          ; /* r14d = len */
                                          ; /* r15d = dist */


        cld
        cmp     r10, rdi
        je      L_one_time           ; /* if only one decode left */
        cmp     r9, rsi

    jne L_do_loop


L_one_time:
        mov     r8, r12           ; /* r8 = lmask */
        cmp     bl, 32
        ja      L_get_length_code_one_time

        lodsd                         ; /* eax = *(uint *)in++ */
        mov     cl, bl            ; /* cl = bits, needs it for shifting */
        add     bl, 32             ; /* bits += 32 */
        shl     rax, cl
        or      rdx, rax          ; /* hold |= *((uint *)in)++ << bits */
        jmp     L_get_length_code_one_time

ALIGN 4
L_while_test:
        cmp     r10, rdi
        jbe     L_break_loop
        cmp     r9, rsi
        jbe     L_break_loop

L_do_loop:
        mov     r8, r12           ; /* r8 = lmask */
        cmp     bl, 32
        ja      L_get_length_code    ; /* if (32 < bits) */

        lodsd                         ; /* eax = *(uint *)in++ */
        mov     cl, bl            ; /* cl = bits, needs it for shifting */
        add     bl, 32             ; /* bits += 32 */
        shl     rax, cl
        or      rdx, rax          ; /* hold |= *((uint *)in)++ << bits */

L_get_length_code:
        and     r8, rdx            ; /* r8 &= hold */
        mov     eax, [rbp+r8*4]  ; /* eax = lcode[hold & lmask] */

        mov     cl, ah            ; /* cl = this.bits */
        sub     bl, ah            ; /* bits -= this.bits */
        shr     rdx, cl           ; /* hold >>= this.bits */

        test    al, al
        jnz     L_test_for_length_base ; /* if (op != 0) 45.7% */

        mov     r8, r12            ; /* r8 = lmask */
        shr     eax, 16            ; /* output this.val char */
        stosb

L_get_length_code_one_time:
        and     r8, rdx            ; /* r8 &= hold */
        mov     eax, [rbp+r8*4] ; /* eax = lcode[hold & lmask] */

L_dolen:
        mov     cl, ah            ; /* cl = this.bits */
        sub     bl, ah            ; /* bits -= this.bits */
        shr     rdx, cl           ; /* hold >>= this.bits */

        test    al, al
        jnz     L_test_for_length_base ; /* if (op != 0) 45.7% */

        shr     eax, 16            ; /* output this.val char */
        stosb
        jmp     L_while_test

ALIGN 4
L_test_for_length_base:
        mov     r14d, eax         ; /* len = this */
        shr     r14d, 16           ; /* len = this.val */
        mov     cl, al

        test    al, 16
        jz      L_test_for_second_level_length ; /* if ((op & 16) == 0) 8% */
        and     cl, 15             ; /* op &= 15 */
        jz      L_decode_distance    ; /* if (!op) */

L_add_bits_to_len:
        sub     bl, cl
        xor     eax, eax
        inc     eax
        shl     eax, cl
        dec     eax
        and     eax, edx          ; /* eax &= hold */
        shr     rdx, cl
        add     r14d, eax         ; /* len += hold & mask[op] */

L_decode_distance:
        mov     r8, r13           ; /* r8 = dmask */
        cmp     bl, 32
        ja      L_get_distance_code  ; /* if (32 < bits) */

        lodsd                         ; /* eax = *(uint *)in++ */
        mov     cl, bl            ; /* cl = bits, needs it for shifting */
        add     bl, 32             ; /* bits += 32 */
        shl     rax, cl
        or      rdx, rax          ; /* hold |= *((uint *)in)++ << bits */

L_get_distance_code:
        and     r8, rdx           ; /* r8 &= hold */
        mov     eax, [r11+r8*4] ; /* eax = dcode[hold & dmask] */

L_dodist:
        mov     r15d, eax         ; /* dist = this */
        shr     r15d, 16           ; /* dist = this.val */
        mov     cl, ah
        sub     bl, ah            ; /* bits -= this.bits */
        shr     rdx, cl           ; /* hold >>= this.bits */
        mov     cl, al            ; /* cl = this.op */

        test    al, 16             ; /* if ((op & 16) == 0) */
        jz      L_test_for_second_level_dist
        and     cl, 15             ; /* op &= 15 */
        jz      L_check_dist_one

L_add_bits_to_dist:
        sub     bl, cl
        xor     eax, eax
        inc     eax
        shl     eax, cl
        dec     eax                 ; /* (1 << op) - 1 */
        and     eax, edx          ; /* eax &= hold */
        shr     rdx, cl
        add     r15d, eax         ; /* dist += hold & ((1 << op) - 1) */

L_check_window:
        mov     r8, rsi           ; /* save in so from can use it's reg */
        mov     rax, rdi
        sub     rax, [rsp+40]      ; /* nbytes = out - beg */

        cmp     eax, r15d
        jb      L_clip_window        ; /* if (dist > nbytes) 4.2% */

        mov     ecx, r14d         ; /* ecx = len */
        mov     rsi, rdi
        sub     rsi, r15          ; /* from = out - dist */

        sar     ecx, 1
        jnc     L_copy_two           ; /* if len % 2 == 0 */

        rep     movsw
        mov     al, [rsi]
        mov     [rdi], al
        inc     rdi

        mov     rsi, r8           ; /* move in back to %rsi, toss from */
        jmp     L_while_test

L_copy_two:
        rep     movsw
        mov     rsi, r8           ; /* move in back to %rsi, toss from */
        jmp     L_while_test

ALIGN 4
L_check_dist_one:
        cmp     r15d, 1            ; /* if dist 1, is a memset */
        jne     L_check_window
        cmp     [rsp+40], rdi      ; /* if out == beg, outside window */
        je      L_check_window

        mov     ecx, r14d         ; /* ecx = len */
        mov     al, [rdi-1]
        mov     ah, al

        sar     ecx, 1
        jnc     L_set_two
        mov     [rdi], al
        inc     rdi

L_set_two:
        rep     stosw
        jmp     L_while_test

ALIGN 4
L_test_for_second_level_length:
        test    al, 64
        jnz     L_test_for_end_of_block ; /* if ((op & 64) != 0) */

        xor     eax, eax
        inc     eax
        shl     eax, cl
        dec     eax
        and     eax, edx         ; /* eax &= hold */
        add     eax, r14d        ; /* eax += len */
        mov     eax, [rbp+rax*4] ; /* eax = lcode[val+(hold&mask[op])]*/
        jmp     L_dolen

ALIGN 4
L_test_for_second_level_dist:
        test    al, 64
        jnz     L_invalid_distance_code ; /* if ((op & 64) != 0) */

        xor     eax, eax
        inc     eax
        shl     eax, cl
        dec     eax
        and     eax, edx         ; /* eax &= hold */
        add     eax, r15d        ; /* eax += dist */
        mov     eax, [r11+rax*4] ; /* eax = dcode[val+(hold&mask[op])]*/
        jmp     L_dodist

ALIGN 4
L_clip_window:
        mov     ecx, eax         ; /* ecx = nbytes */
        mov     eax, [rsp+92]     ; /* eax = wsize, prepare for dist cmp */
        neg     ecx                ; /* nbytes = -nbytes */

        cmp     eax, r15d
        jb      L_invalid_distance_too_far ; /* if (dist > wsize) */

        add     ecx, r15d         ; /* nbytes = dist - nbytes */
        cmp     dword ptr [rsp+96], 0
        jne     L_wrap_around_window ; /* if (write != 0) */

        mov     rsi, [rsp+56]     ; /* from  = window */
        sub     eax, ecx         ; /* eax  -= nbytes */
        add     rsi, rax         ; /* from += wsize - nbytes */

        mov     eax, r14d        ; /* eax = len */
        cmp     r14d, ecx
        jbe     L_do_copy           ; /* if (nbytes >= len) */

        sub     eax, ecx         ; /* eax -= nbytes */
        rep     movsb
        mov     rsi, rdi
        sub     rsi, r15         ; /* from = &out[ -dist ] */
        jmp     L_do_copy

ALIGN 4
L_wrap_around_window:
        mov     eax, [rsp+96]     ; /* eax = write */
        cmp     ecx, eax
        jbe     L_contiguous_in_window ; /* if (write >= nbytes) */

        mov     esi, [rsp+92]     ; /* from  = wsize */
        add     rsi, [rsp+56]     ; /* from += window */
        add     rsi, rax         ; /* from += write */
        sub     rsi, rcx         ; /* from -= nbytes */
        sub     ecx, eax         ; /* nbytes -= write */

        mov     eax, r14d        ; /* eax = len */
        cmp     eax, ecx
        jbe     L_do_copy           ; /* if (nbytes >= len) */

        sub     eax, ecx         ; /* len -= nbytes */
        rep     movsb
        mov     rsi, [rsp+56]     ; /* from = window */
        mov     ecx, [rsp+96]     ; /* nbytes = write */
        cmp     eax, ecx
        jbe     L_do_copy           ; /* if (nbytes >= len) */

        sub     eax, ecx         ; /* len -= nbytes */
        rep     movsb
        mov     rsi, rdi
        sub     rsi, r15         ; /* from = out - dist */
        jmp     L_do_copy

ALIGN 4
L_contiguous_in_window:
        mov     rsi, [rsp+56]     ; /* rsi = window */
        add     rsi, rax
        sub     rsi, rcx         ; /* from += write - nbytes */

        mov     eax, r14d        ; /* eax = len */
        cmp     eax, ecx
        jbe     L_do_copy           ; /* if (nbytes >= len) */

        sub     eax, ecx         ; /* len -= nbytes */
        rep     movsb
        mov     rsi, rdi
        sub     rsi, r15         ; /* from = out - dist */
        jmp     L_do_copy           ; /* if (nbytes >= len) */

ALIGN 4
L_do_copy:
        mov     ecx, eax         ; /* ecx = len */
        rep     movsb

        mov     rsi, r8          ; /* move in back to %esi, toss from */
        jmp     L_while_test

L_test_for_end_of_block:
        test    al, 32
        jz      L_invalid_literal_length_code
        mov     dword ptr [rsp+116], 1
        jmp     L_break_loop_with_status

L_invalid_literal_length_code:
        mov     dword ptr [rsp+116], 2
        jmp     L_break_loop_with_status

L_invalid_distance_code:
        mov     dword ptr [rsp+116], 3
        jmp     L_break_loop_with_status

L_invalid_distance_too_far:
        mov     dword ptr [rsp+116], 4
        jmp     L_break_loop_with_status

L_break_loop:
        mov     dword ptr [rsp+116], 0

L_break_loop_with_status:
; /* put in, out, bits, and hold back into ar and pop esp */
        mov     [rsp+16], rsi     ; /* in */
        mov     [rsp+32], rdi     ; /* out */
        mov     [rsp+88], ebx     ; /* bits */
        mov     [rsp+80], rdx     ; /* hold */

        mov     rax, [rsp]       ; /* restore rbp and rsp */
        mov     rbp, [rsp+8]
        mov     rsp, rax



        mov rsi,[rsp-8]
        mov rdi,[rsp-16]
        mov r12,[rsp-24]
        mov r13,[rsp-32]
        mov r14,[rsp-40]
        mov r15,[rsp-48]
        mov rbx,[rsp-56]
        
    ret 0
;          :
;          : "m" (ar)
;          : "memory", "%rax", "%rbx", "%rcx", "%rdx", "%rsi", "%rdi",
;            "%r8", "%r9", "%r10", "%r11", "%r12", "%r13", "%r14", "%r15"
;    );

inffas8664fnc   ENDP
;_TEXT  ENDS
END