arch/alpha/lib/memset.S

   1 /*
   2  * linux/arch/alpha/lib/memset.S
   3  *
   4  * This is an efficient (and small) implementation of the C library "memset()"
   5  * function for the alpha.
   6  *
   7  *      (C) Copyright 1996 Linus Torvalds
   8  *
   9  * This routine is "moral-ware": you are free to use it any way you wish, and
  10  * the only obligation I put on you is a moral one: if you make any improvements
  11  * to the routine, please send me your improvements for me to use similarly.
  12  *
  13  * The scheduling comments are according to the EV5 documentation (and done by
  14  * hand, so they might well be incorrect, please do tell me about it..)
  15  */
  16
  17         .set noat
  18         .set noreorder
  19 .text
  20         .globl memset
  21         .globl __memset
  22         .globl ___memset
  23         .globl __memsetw
  24         .globl __constant_c_memset
  25
  26         .ent ___memset
  27 .align 5
  28 ___memset:
  29         .frame $30,0,$26,0
  30         .prologue 0
  31
  32         and $17,255,$1          /* E1 */
  33         insbl $17,1,$17         /* .. E0 */
  34         bis $17,$1,$17          /* E0 (p-c latency, next cycle) */
  35         sll $17,16,$1           /* E1 (p-c latency, next cycle) */
  36
  37         bis $17,$1,$17          /* E0 (p-c latency, next cycle) */
  38         sll $17,32,$1           /* E1 (p-c latency, next cycle) */
  39         bis $17,$1,$17          /* E0 (p-c latency, next cycle) */
  40         ldq_u $31,0($30)        /* .. E1 */
  41
  42 .align 5
  43 __constant_c_memset:
  44         addq $18,$16,$6         /* E0 */
  45         bis $16,$16,$0          /* .. E1 */
  46         xor $16,$6,$1           /* E0 */
  47         ble $18,end             /* .. E1 */
  48
  49         bic $1,7,$1             /* E0 */
  50         beq $1,within_one_quad  /* .. E1 (note EV5 zero-latency forwarding) */
  51         and $16,7,$3            /* E0 */
  52         beq $3,aligned          /* .. E1 (note EV5 zero-latency forwarding) */
  53
  54         ldq_u $4,0($16)         /* E0 */
  55         bis $16,$16,$5          /* .. E1 */
  56         insql $17,$16,$2        /* E0 */
  57         subq $3,8,$3            /* .. E1 */
  58
  59         addq $18,$3,$18         /* E0   $18 is new count ($3 is negative) */
  60         mskql $4,$16,$4         /* .. E1 (and possible load stall) */
  61         subq $16,$3,$16         /* E0   $16 is new aligned destination */
  62         bis $2,$4,$1            /* .. E1 */
  63
  64         bis $31,$31,$31         /* E0 */
  65         ldq_u $31,0($30)        /* .. E1 */
  66         stq_u $1,0($5)          /* E0 */
  67         bis $31,$31,$31         /* .. E1 */
  68
  69 .align 4
  70 aligned:
  71         sra $18,3,$3            /* E0 */
  72         and $18,7,$18           /* .. E1 */
  73         bis $16,$16,$5          /* E0 */
  74         beq $3,no_quad          /* .. E1 */
  75
  76 .align 3
  77 loop:
  78         stq $17,0($5)           /* E0 */
  79         subq $3,1,$3            /* .. E1 */
  80         addq $5,8,$5            /* E0 */
  81         bne $3,loop             /* .. E1 */
  82
  83 no_quad:
  84         bis $31,$31,$31         /* E0 */
  85         beq $18,end             /* .. E1 */
  86         ldq $7,0($5)            /* E0 */
  87         mskqh $7,$6,$2          /* .. E1 (and load stall) */
  88
  89         insqh $17,$6,$4         /* E0 */
  90         bis $2,$4,$1            /* .. E1 */
  91         stq $1,0($5)            /* E0 */
  92         ret $31,($26),1         /* .. E1 */
  93
  94 .align 3
  95 within_one_quad:
  96         ldq_u $1,0($16)         /* E0 */
  97         insql $17,$16,$2        /* E1 */
  98         mskql $1,$16,$4         /* E0 (after load stall) */
  99         bis $2,$4,$2            /* E0 */
 100
 101         mskql $2,$6,$4          /* E0 */
 102         mskqh $1,$6,$2          /* .. E1 */
 103         bis $2,$4,$1            /* E0 */
 104         stq_u $1,0($16)         /* E0 */
 105
 106 end:
 107         ret $31,($26),1         /* E1 */
 108         .end ___memset
 109
 110         .align 5
 111         .ent __memsetw
 112 __memsetw:
 113         .prologue 0
 114
 115         inswl $17,0,$1          /* E0 */
 116         inswl $17,2,$2          /* E0 */
 117         inswl $17,4,$3          /* E0 */
 118         or $1,$2,$1             /* .. E1 */
 119         inswl $17,6,$4          /* E0 */
 120         or $1,$3,$1             /* .. E1 */
 121         or $1,$4,$17            /* E0 */
 122         br __constant_c_memset  /* .. E1 */
 123
 124         .end __memsetw
 125
 126 memset = ___memset
 127 __memset = ___memset