sdcc/device/lib/_memset.c

   1 /*-------------------------------------------------------------------------
   2    _memset.c - part of string library functions
   3
   4    Copyright (C) 1999, Sandeep Dutta . sandeep.dutta@usa.net
   5    Copyright (C) 2020, Sergey Belyashov sergey.belyashov@gmail.com
   6    Copyright (C) 2022, Sebastian 'basxto' Riedel
   7    mcs51 assembler by Frieder Ferlemann (2007)
   8
   9    This library is free software; you can redistribute it and/or modify it
  10    under the terms of the GNU General Public License as published by the
  11    Free Software Foundation; either version 2, or (at your option) any
  12    later version.
  13
  14    This library is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this library; see the file COPYING. If not, write to the
  21    Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
  22    MA 02110-1301, USA.
  23
  24    As a special exception, if you link this library with other files,
  25    some of which are compiled with SDCC, to produce an executable,
  26    this library does not by itself cause the resulting executable to
  27    be covered by the GNU General Public License. This exception does
  28    not however invalidate any other reasons why the executable file
  29    might be covered by the GNU General Public License.
  30 -------------------------------------------------------------------------*/
  31
  32 #include <stdlib.h>
  33 #include <string.h>
  34
  35 #undef memset /* Avoid conflict with builtin memset() in Z80 and some related ports */
  36
  37 #if defined (_SDCC_NO_ASM_LIB_FUNCS) || !defined (__SDCC_mcs51) || \
  38     (!defined (__SDCC_MODEL_SMALL) && !defined (__SDCC_MODEL_LARGE)) || \
  39      (defined (__SDCC_STACK_AUTO) || defined (__SDCC_PARMS_IN_BANK1) )
  40
  41 #ifdef __SDCC_BROKEN_STRING_FUNCTIONS
  42 void *memset (void *s, unsigned char c, size_t n)
  43 #else
  44 void *memset (void *s, int c, size_t n)
  45 #endif
  46
  47 #if !defined (_SDCC_NO_ASM_LIB_FUNCS) && (\
  48               defined (__SDCC_z80) ||\
  49               defined (__SDCC_z180) ||\
  50               defined (__SDCC_z80n) ||\
  51               defined (__SDCC_r800))
  52 #ifdef __SDCC_BROKEN_STRING_FUNCTIONS
  53 #error Unimplemented broken string function
  54 #endif
  55 __naked
  56 {
  57   (void)s;
  58   (void)c;
  59   (void)n;
  60   __asm
  61     pop   iy
  62     pop   bc
  63     push  hl
  64     ld    a, c
  65     or    a, b
  66     jr    Z, end
  67     ld    (hl), e
  68     dec   bc
  69     ld    a, c
  70     or    a, b
  71     jr    Z, end
  72     ld    e, l
  73     ld    d, h
  74     inc   de
  75     ldir
  76 end:
  77     pop   de
  78     jp  (iy)
  79   __endasm;
  80 }
  81 #elif !defined (_SDCC_NO_ASM_LIB_FUNCS) && defined(__SDCC_sm83)
  82 __naked
  83 {
  84         (void)s;//de
  85         (void)c;//bc or for broken string function in a
  86         (void)n;//stack+2, stack+3
  87 __asm
  88         ; Algorithm is Duff`s device
  89         ldhl    sp,     #3
  90 __endasm;
  91 #ifdef __SDCC_BROKEN_STRING_FUNCTIONS
  92 __asm
  93         ld      b, (hl)
  94         dec     hl
  95 __endasm;
  96 #else
  97 __asm
  98
  99         ld      a, (hl-)
 100         ld      b, a
 101         ld      a, c
 102 __endasm;
 103 #endif
 104 __asm
 105         ld      c, (hl)
 106         ld      l, e
 107         ld      h, d
 108         ;shift LSB to carry
 109         srl     b
 110         rr      c
 111         jr nc, skip_one
 112         ld      (hl+), a
 113 skip_one:
 114         ;n/2 in bc
 115         ;shift second LSB to carry
 116         srl     b
 117         rr      c
 118         ;n/4 in bc
 119         inc     b
 120         inc     c
 121         jr nc, test
 122         jr      copy_two
 123 copy_four:
 124         ld      (hl+), a
 125         ld      (hl+), a
 126 copy_two:
 127         ld      (hl+), a
 128         ld      (hl+), a
 129 test:
 130         dec     c
 131         jr      NZ, copy_four
 132         dec     b
 133         jr      NZ, copy_four
 134         ;restore dest
 135         ld      c, e
 136         ld      b, d
 137         pop     hl
 138         pop     af
 139         jp      (hl)
 140 __endasm;
 141 }
 142 #else
 143 {
 144   register size_t sz = n;
 145   if (sz != 0)
 146     {
 147       register char *dst = s;
 148       register char data = (char)c;
 149       do {
 150         *dst++ = data;
 151       } while (--sz);
 152     }
 153   return s;
 154 }
 155 #endif
 156 #else
 157
 158   /* assembler implementation for mcs51 */
 159   static void dummy(void) __naked
 160   {
 161     __asm
 162
 163   /* assigning function parameters to registers.
 164      __SDCC_PARMS_IN_BANK1 or __SDCC_STACK_AUTO not yet implemented. */
 165   #if defined (__SDCC_MODEL_SMALL)
 166
 167     #if defined(__SDCC_NOOVERLAY)
 168         .area DSEG    (DATA)
 169     #else
 170         .area OSEG    (OVR,DATA)
 171     #endif
 172         _memset_PARM_2::
 173               .ds 1
 174         _memset_PARM_3::
 175               .ds 2
 176
 177         .area CSEG    (CODE)
 178
 179         _memset::
 180
 181         ;   Assign buf (b holds memspace, no need to touch)
 182                 mov     r4,dpl
 183                 mov     r5,dph
 184                 ;
 185         ;   Assign count
 186                 mov     r6,_memset_PARM_3
 187                 mov     r7,(_memset_PARM_3 + 1)
 188                 ;
 189         ;   if (!count) return buf;
 190         ;   check for count != 0 intermangled with gymnastic
 191         ;   preparing djnz instructions
 192                 cjne    r6,#0x00,COUNT_LSB_NOT_ZERO
 193                 mov     a,r7
 194                 jz      MEMSET_END
 195                 dec     r7
 196         COUNT_LSB_NOT_ZERO:
 197                 inc     r7
 198                 ;
 199                 ; This was 8 byte overhead for preparing
 200                 ; the count argument for an integer loop with two
 201                 ; djnz instructions - it might make sense to
 202                 ; let SDCC automatically generate this when
 203                 ; it encounters a loop like:
 204                 ; for(i=0;i<j;i++){...}
 205                 ; (at least for option --opt-code-speed)
 206                 ;
 207
 208         ;   Assign ch
 209                 mov     a,_memset_PARM_2
 210
 211   #else
 212
 213         .area XSEG    (XDATA)
 214
 215         _memset_PARM_2::
 216                 .ds 1
 217         _memset_PARM_3::
 218                 .ds 2
 219
 220         .area CSEG    (CODE)
 221
 222         _memset::
 223
 224         ;   Assign buf (b holds memspace, no need to touch)
 225                 mov     r4,dpl
 226                 mov     r5,dph
 227                 ;
 228         ;   Assign count
 229                 mov     dptr,#_memset_PARM_3
 230                 movx    a,@dptr
 231                 mov     r6,a
 232                 inc     dptr
 233                 movx    a,@dptr
 234                 mov     r7,a
 235                 ;
 236         ;   if (!count) return buf;
 237         ;   check for count != 0 intermangled with gymnastic
 238         ;   preparing djnz instructions
 239                 cjne    r6,#0x00,COUNT_LSB_NOT_ZERO
 240         ;   acc holds r7
 241                 jz      MEMSET_END
 242                 dec     r7
 243         COUNT_LSB_NOT_ZERO:
 244                 inc     r7
 245                 ;
 246         ;   Assign ch
 247                 mov     dptr,#_memset_PARM_2
 248                 movx    a,@dptr
 249         ;   acc is precious now
 250                 ;
 251         ;   Restore dptr
 252                 mov     dpl,r4
 253                 mov     dph,r5
 254
 255   #endif
 256
 257         /* now independent of the parameter passing everything
 258            should be in registers by now and the loop may start */
 259         ;   _memset.c do {
 260
 261         MEMSET_LOOP:
 262         ;   _memset.c *p = ch;
 263                 lcall   __gptrput
 264
 265         ;   _memset.c p++;
 266                 inc     dptr
 267
 268         ;   _memset.c } while(--count) ;
 269                 djnz    r6,MEMSET_LOOP
 270                 djnz    r7,MEMSET_LOOP
 271                 ;
 272
 273         MEMSET_END:
 274         ;   _memset.c return buf ;
 275                 ; b was unchanged
 276                 mov     dpl,r4
 277                 mov     dph,r5
 278                 ;
 279                 ret
 280
 281     __endasm;
 282   }
 283
 284 #endif