/* SPDX-License-Identifier: GPL-2.0 */
/* checksum.S: Sparc V9 optimized checksum code.
 *
 *  Copyright(C) 1995 Linus Torvalds
 *  Copyright(C) 1995 Miguel de Icaza
 *  Copyright(C) 1996, 2000 David S. Miller
 *  Copyright(C) 1997 Jakub Jelinek
 *
 * derived from:
 *      Linux/Alpha checksum c-code
 *      Linux/ix86 inline checksum assembly
 *      RFC1071 Computing the Internet Checksum (esp. Jacobsons m68k code)
 *      David Mosberger-Tang for optimized reference c-code
 *      BSD4.4 portable checksum routine
 */

#include <linux/export.h>
        .text

csum_partial_fix_alignment:
        /* We checked for zero length already, so there must be
         * at least one byte.
         */
        be,pt           %icc, 1f
         nop
        ldub            [%o0 + 0x00], %o4
        add             %o0, 1, %o0
        sub             %o1, 1, %o1
1:      andcc           %o0, 0x2, %g0
        be,pn           %icc, csum_partial_post_align
         cmp            %o1, 2
        blu,pn          %icc, csum_partial_end_cruft
         nop
        lduh            [%o0 + 0x00], %o5
        add             %o0, 2, %o0
        sub             %o1, 2, %o1
        ba,pt           %xcc, csum_partial_post_align
         add            %o5, %o4, %o4

        .align          32
        .globl          csum_partial
        .type           csum_partial,#function
        EXPORT_SYMBOL(csum_partial)
csum_partial:           /* %o0=buff, %o1=len, %o2=sum */
        prefetch        [%o0 + 0x000], #n_reads
        clr             %o4
        prefetch        [%o0 + 0x040], #n_reads
        brz,pn          %o1, csum_partial_finish
         andcc          %o0, 0x3, %g0

        /* We "remember" whether the lowest bit in the address
         * was set in %g7.  Because if it is, we have to swap
         * upper and lower 8 bit fields of the sum we calculate.
        */
        bne,pn          %icc, csum_partial_fix_alignment
         andcc          %o0, 0x1, %g7

csum_partial_post_align:
        prefetch        [%o0 + 0x080], #n_reads
        andncc          %o1, 0x3f, %o3

        prefetch        [%o0 + 0x0c0], #n_reads
        sub             %o1, %o3, %o1
        brz,pn          %o3, 2f
         prefetch       [%o0 + 0x100], #n_reads

        /* So that we don't need to use the non-pairing
         * add-with-carry instructions we accumulate 32-bit
         * values into a 64-bit register.  At the end of the
         * loop we fold it down to 32-bits and so on.
         */
        prefetch        [%o0 + 0x140], #n_reads
1:      lduw            [%o0 + 0x00], %o5
        lduw            [%o0 + 0x04], %g1
        lduw            [%o0 + 0x08], %g2
        add             %o4, %o5, %o4
        lduw            [%o0 + 0x0c], %g3
        add             %o4, %g1, %o4
        lduw            [%o0 + 0x10], %o5
        add             %o4, %g2, %o4
        lduw            [%o0 + 0x14], %g1
        add             %o4, %g3, %o4
        lduw            [%o0 + 0x18], %g2
        add             %o4, %o5, %o4
        lduw            [%o0 + 0x1c], %g3
        add             %o4, %g1, %o4
        lduw            [%o0 + 0x20], %o5
        add             %o4, %g2, %o4
        lduw            [%o0 + 0x24], %g1
        add             %o4, %g3, %o4
        lduw            [%o0 + 0x28], %g2
        add             %o4, %o5, %o4
        lduw            [%o0 + 0x2c], %g3
        add             %o4, %g1, %o4
        lduw            [%o0 + 0x30], %o5
        add             %o4, %g2, %o4
        lduw            [%o0 + 0x34], %g1
        add             %o4, %g3, %o4
        lduw            [%o0 + 0x38], %g2
        add             %o4, %o5, %o4
        lduw            [%o0 + 0x3c], %g3
        add             %o4, %g1, %o4
        prefetch        [%o0 + 0x180], #n_reads
        add             %o4, %g2, %o4
        subcc           %o3, 0x40, %o3
        add             %o0, 0x40, %o0
        bne,pt          %icc, 1b
         add            %o4, %g3, %o4

2:      and             %o1, 0x3c, %o3
        brz,pn          %o3, 2f
         sub            %o1, %o3, %o1
1:      lduw            [%o0 + 0x00], %o5
        subcc           %o3, 0x4, %o3
        add             %o0, 0x4, %o0
        bne,pt          %icc, 1b
         add            %o4, %o5, %o4

2:
        /* fold 64-->32 */
        srlx            %o4, 32, %o5
        srl             %o4, 0, %o4
        add             %o4, %o5, %o4
        srlx            %o4, 32, %o5
        srl             %o4, 0, %o4
        add             %o4, %o5, %o4

        /* fold 32-->16 */
        sethi           %hi(0xffff0000), %g1
        srl             %o4, 16, %o5
        andn            %o4, %g1, %g2
        add             %o5, %g2, %o4
        srl             %o4, 16, %o5
        andn            %o4, %g1, %g2
        add             %o5, %g2, %o4

csum_partial_end_cruft:
        /* %o4 has the 16-bit sum we have calculated so-far.  */
        cmp             %o1, 2
        blu,pt          %icc, 1f
         nop
        lduh            [%o0 + 0x00], %o5
        sub             %o1, 2, %o1
        add             %o0, 2, %o0
        add             %o4, %o5, %o4
1:      brz,pt          %o1, 1f
         nop
        ldub            [%o0 + 0x00], %o5
        sub             %o1, 1, %o1
        add             %o0, 1, %o0
        sllx            %o5, 8, %o5
        add             %o4, %o5, %o4
1:
        /* fold 32-->16 */
        sethi           %hi(0xffff0000), %g1
        srl             %o4, 16, %o5
        andn            %o4, %g1, %g2
        add             %o5, %g2, %o4
        srl             %o4, 16, %o5
        andn            %o4, %g1, %g2
        add             %o5, %g2, %o4

1:      brz,pt          %g7, 1f
         nop

        /* We started with an odd byte, byte-swap the result.  */
        srl             %o4, 8, %o5
        and             %o4, 0xff, %g1
        sll             %g1, 8, %g1
        or              %o5, %g1, %o4

1:      addcc           %o2, %o4, %o2
        addc            %g0, %o2, %o2

csum_partial_finish:
        retl
         srl            %o2, 0, %o0