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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* linux/arch/arm/lib/ll_char_wr.S
*
* Copyright (C) 1995, 1996 Russell King.
*
* Speedups & 1bpp code (C) 1996 Philip Blundell & Russell King.
*
* 10-04-96 RMK Various cleanups & reduced register usage.
* 08-04-98 RMK Shifts re-ordered
*/
@ Regs: [] = corruptible
@ {} = used
@ () = do not use
#include <linux/linkage.h>
#include <asm/assembler.h>
.text
LC0: .word LC0
.word bytes_per_char_h
.word video_size_row
.word acorndata_8x8
.word con_charconvtable
/*
* r0 = ptr
* r1 = char
* r2 = white
*/
ENTRY(ll_write_char)
stmfd sp!, {r4 - r7, lr}
@
@ Smashable regs: {r0 - r3}, [r4 - r7], (r8 - fp), [ip], (sp), [lr], (pc)
@
/*
* calculate offset into character table
*/
mov r1, r1, lsl #3
/*
* calculate offset required for each row.
*/
adr ip, LC0
ldmia ip, {r3, r4, r5, r6, lr}
sub ip, ip, r3
add r6, r6, ip
add lr, lr, ip
ldr r4, [r4, ip]
ldr r5, [r5, ip]
/*
* Go to resolution-dependent routine...
*/
cmp r4, #4
blt Lrow1bpp
add r0, r0, r5, lsl #3 @ Move to bottom of character
orr r1, r1, #7
ldrb r7, [r6, r1]
teq r4, #8
beq Lrow8bpplp
@
@ Smashable regs: {r0 - r3}, [r4], {r5 - r7}, (r8 - fp), [ip], (sp), {lr}, (pc)
@
Lrow4bpplp:
ldr r7, [lr, r7, lsl #2]
mul r7, r2, r7
sub r1, r1, #1 @ avoid using r7 directly after
str r7, [r0, -r5]!
ldrb r7, [r6, r1]
ldr r7, [lr, r7, lsl #2]
mul r7, r2, r7
tst r1, #7 @ avoid using r7 directly after
str r7, [r0, -r5]!
subne r1, r1, #1
ldrbne r7, [r6, r1]
bne Lrow4bpplp
ldmfd sp!, {r4 - r7, pc}
@
@ Smashable regs: {r0 - r3}, [r4], {r5 - r7}, (r8 - fp), [ip], (sp), {lr}, (pc)
@
Lrow8bpplp:
mov ip, r7, lsr #4
ldr ip, [lr, ip, lsl #2]
mul r4, r2, ip
and ip, r7, #15 @ avoid r4
ldr ip, [lr, ip, lsl #2] @ avoid r4
mul ip, r2, ip @ avoid r4
sub r1, r1, #1 @ avoid ip
sub r0, r0, r5 @ avoid ip
stmia r0, {r4, ip}
ldrb r7, [r6, r1]
mov ip, r7, lsr #4
ldr ip, [lr, ip, lsl #2]
mul r4, r2, ip
and ip, r7, #15 @ avoid r4
ldr ip, [lr, ip, lsl #2] @ avoid r4
mul ip, r2, ip @ avoid r4
tst r1, #7 @ avoid ip
sub r0, r0, r5 @ avoid ip
stmia r0, {r4, ip}
subne r1, r1, #1
ldrbne r7, [r6, r1]
bne Lrow8bpplp
ldmfd sp!, {r4 - r7, pc}
@
@ Smashable regs: {r0 - r3}, [r4], {r5, r6}, [r7], (r8 - fp), [ip], (sp), [lr], (pc)
@
Lrow1bpp:
add r6, r6, r1
ldmia r6, {r4, r7}
strb r4, [r0], r5
mov r4, r4, lsr #8
strb r4, [r0], r5
mov r4, r4, lsr #8
strb r4, [r0], r5
mov r4, r4, lsr #8
strb r4, [r0], r5
strb r7, [r0], r5
mov r7, r7, lsr #8
strb r7, [r0], r5
mov r7, r7, lsr #8
strb r7, [r0], r5
mov r7, r7, lsr #8
strb r7, [r0], r5
ldmfd sp!, {r4 - r7, pc}
.bss
ENTRY(con_charconvtable)
.space 1024
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