root/arch/riscv/lib/memcpy.S

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright (C) 2013 Regents of the University of California
   4  */
   5 
   6 #include <linux/linkage.h>
   7 #include <asm/asm.h>
   8 
   9 /* void *memcpy(void *, const void *, size_t) */
  10 ENTRY(memcpy)
  11         move t6, a0  /* Preserve return value */
  12 
  13         /* Defer to byte-oriented copy for small sizes */
  14         sltiu a3, a2, 128
  15         bnez a3, 4f
  16         /* Use word-oriented copy only if low-order bits match */
  17         andi a3, t6, SZREG-1
  18         andi a4, a1, SZREG-1
  19         bne a3, a4, 4f
  20 
  21         beqz a3, 2f  /* Skip if already aligned */
  22         /*
  23          * Round to nearest double word-aligned address
  24          * greater than or equal to start address
  25          */
  26         andi a3, a1, ~(SZREG-1)
  27         addi a3, a3, SZREG
  28         /* Handle initial misalignment */
  29         sub a4, a3, a1
  30 1:
  31         lb a5, 0(a1)
  32         addi a1, a1, 1
  33         sb a5, 0(t6)
  34         addi t6, t6, 1
  35         bltu a1, a3, 1b
  36         sub a2, a2, a4  /* Update count */
  37 
  38 2:
  39         andi a4, a2, ~((16*SZREG)-1)
  40         beqz a4, 4f
  41         add a3, a1, a4
  42 3:
  43         REG_L a4,       0(a1)
  44         REG_L a5,   SZREG(a1)
  45         REG_L a6, 2*SZREG(a1)
  46         REG_L a7, 3*SZREG(a1)
  47         REG_L t0, 4*SZREG(a1)
  48         REG_L t1, 5*SZREG(a1)
  49         REG_L t2, 6*SZREG(a1)
  50         REG_L t3, 7*SZREG(a1)
  51         REG_L t4, 8*SZREG(a1)
  52         REG_L t5, 9*SZREG(a1)
  53         REG_S a4,       0(t6)
  54         REG_S a5,   SZREG(t6)
  55         REG_S a6, 2*SZREG(t6)
  56         REG_S a7, 3*SZREG(t6)
  57         REG_S t0, 4*SZREG(t6)
  58         REG_S t1, 5*SZREG(t6)
  59         REG_S t2, 6*SZREG(t6)
  60         REG_S t3, 7*SZREG(t6)
  61         REG_S t4, 8*SZREG(t6)
  62         REG_S t5, 9*SZREG(t6)
  63         REG_L a4, 10*SZREG(a1)
  64         REG_L a5, 11*SZREG(a1)
  65         REG_L a6, 12*SZREG(a1)
  66         REG_L a7, 13*SZREG(a1)
  67         REG_L t0, 14*SZREG(a1)
  68         REG_L t1, 15*SZREG(a1)
  69         addi a1, a1, 16*SZREG
  70         REG_S a4, 10*SZREG(t6)
  71         REG_S a5, 11*SZREG(t6)
  72         REG_S a6, 12*SZREG(t6)
  73         REG_S a7, 13*SZREG(t6)
  74         REG_S t0, 14*SZREG(t6)
  75         REG_S t1, 15*SZREG(t6)
  76         addi t6, t6, 16*SZREG
  77         bltu a1, a3, 3b
  78         andi a2, a2, (16*SZREG)-1  /* Update count */
  79 
  80 4:
  81         /* Handle trailing misalignment */
  82         beqz a2, 6f
  83         add a3, a1, a2
  84 
  85         /* Use word-oriented copy if co-aligned to word boundary */
  86         or a5, a1, t6
  87         or a5, a5, a3
  88         andi a5, a5, 3
  89         bnez a5, 5f
  90 7:
  91         lw a4, 0(a1)
  92         addi a1, a1, 4
  93         sw a4, 0(t6)
  94         addi t6, t6, 4
  95         bltu a1, a3, 7b
  96 
  97         ret
  98 
  99 5:
 100         lb a4, 0(a1)
 101         addi a1, a1, 1
 102         sb a4, 0(t6)
 103         addi t6, t6, 1
 104         bltu a1, a3, 5b
 105 6:
 106         ret
 107 END(memcpy)