root/arch/arm/lib/io-readsb.S
/* SPDX-License-Identifier: GPL-2.0-only */
/*
 *  linux/arch/arm/lib/io-readsb.S
 *
 *  Copyright (C) 1995-2000 Russell King
 */
#include <linux/linkage.h>
#include <asm/assembler.h>

.Linsb_align:   rsb     ip, ip, #4
                cmp     ip, r2
                movgt   ip, r2
                cmp     ip, #2
                ldrb    r3, [r0]
                strb    r3, [r1], #1
                ldrbge  r3, [r0]
                strbge  r3, [r1], #1
                ldrbgt  r3, [r0]
                strbgt  r3, [r1], #1
                subs    r2, r2, ip
                bne     .Linsb_aligned

ENTRY(__raw_readsb)
                teq     r2, #0          @ do we have to check for the zero len?
                reteq   lr
                ands    ip, r1, #3
                bne     .Linsb_align

.Linsb_aligned: stmfd   sp!, {r4 - r6, lr}

                subs    r2, r2, #16
                bmi     .Linsb_no_16

.Linsb_16_lp:   ldrb    r3, [r0]
                ldrb    r4, [r0]
                ldrb    r5, [r0]
                mov     r3, r3,     put_byte_0
                ldrb    r6, [r0]
                orr     r3, r3, r4, put_byte_1
                ldrb    r4, [r0]
                orr     r3, r3, r5, put_byte_2
                ldrb    r5, [r0]
                orr     r3, r3, r6, put_byte_3
                ldrb    r6, [r0]
                mov     r4, r4,     put_byte_0
                ldrb    ip, [r0]
                orr     r4, r4, r5, put_byte_1
                ldrb    r5, [r0]
                orr     r4, r4, r6, put_byte_2
                ldrb    r6, [r0]
                orr     r4, r4, ip, put_byte_3
                ldrb    ip, [r0]
                mov     r5, r5,     put_byte_0
                ldrb    lr, [r0]
                orr     r5, r5, r6, put_byte_1
                ldrb    r6, [r0]
                orr     r5, r5, ip, put_byte_2
                ldrb    ip, [r0]
                orr     r5, r5, lr, put_byte_3
                ldrb    lr, [r0]
                mov     r6, r6,     put_byte_0
                orr     r6, r6, ip, put_byte_1
                ldrb    ip, [r0]
                orr     r6, r6, lr, put_byte_2
                orr     r6, r6, ip, put_byte_3
                stmia   r1!, {r3 - r6}

                subs    r2, r2, #16
                bpl     .Linsb_16_lp

                tst     r2, #15
                ldmfdeq sp!, {r4 - r6, pc}

.Linsb_no_16:   tst     r2, #8
                beq     .Linsb_no_8

                ldrb    r3, [r0]
                ldrb    r4, [r0]
                ldrb    r5, [r0]
                mov     r3, r3,     put_byte_0
                ldrb    r6, [r0]
                orr     r3, r3, r4, put_byte_1
                ldrb    r4, [r0]
                orr     r3, r3, r5, put_byte_2
                ldrb    r5, [r0]
                orr     r3, r3, r6, put_byte_3
                ldrb    r6, [r0]
                mov     r4, r4,     put_byte_0
                ldrb    ip, [r0]
                orr     r4, r4, r5, put_byte_1
                orr     r4, r4, r6, put_byte_2
                orr     r4, r4, ip, put_byte_3
                stmia   r1!, {r3, r4}

.Linsb_no_8:    tst     r2, #4
                beq     .Linsb_no_4

                ldrb    r3, [r0]
                ldrb    r4, [r0]
                ldrb    r5, [r0]
                ldrb    r6, [r0]
                mov     r3, r3,     put_byte_0
                orr     r3, r3, r4, put_byte_1
                orr     r3, r3, r5, put_byte_2
                orr     r3, r3, r6, put_byte_3
                str     r3, [r1], #4

.Linsb_no_4:    ands    r2, r2, #3
                ldmfdeq sp!, {r4 - r6, pc}

                cmp     r2, #2
                ldrb    r3, [r0]
                strb    r3, [r1], #1
                ldrbge  r3, [r0]
                strbge  r3, [r1], #1
                ldrbgt  r3, [r0]
                strbgt  r3, [r1]

                ldmfd   sp!, {r4 - r6, pc}
ENDPROC(__raw_readsb)