dos/getsetsl.c

   1 /*
   2  * Special handling for the MS-DOS derivative: syslinux_ldlinux
   3  * is a "far" object...
   4  */
   5
   6 #define _XOPEN_SOURCE 500       /* Required on glibc 2.x */
   7 #define _BSD_SOURCE
   8 /* glibc 2.20 deprecates _BSD_SOURCE in favour of _DEFAULT_SOURCE */
   9 #define _DEFAULT_SOURCE 1
  10 #include <inttypes.h>
  11 #include <string.h>
  12 #include <stddef.h>
  13 #include <stdlib.h>
  14
  15 #include "syslxint.h"
  16 #include "mystuff.h"
  17
  18 static inline void *set_fs_sl(const void *p)
  19 {
  20     uint16_t seg;
  21
  22     seg = ds() + ((size_t) p >> 4);
  23     set_fs(seg);
  24     return (void *)((size_t) p & 0xf);
  25 }
  26
  27 #if 0                           /* unused */
  28 uint8_t get_8_sl(const uint8_t * p)
  29 {
  30     uint8_t v;
  31
  32     p = set_fs_sl(p);
  33     asm volatile("movb %%fs:%1,%0":"=q" (v):"m"(*p));
  34     return v;
  35 }
  36 #endif
  37
  38 uint16_t get_16_sl(const uint16_t * p)
  39 {
  40     uint16_t v;
  41
  42     p = set_fs_sl(p);
  43     asm volatile("movw %%fs:%1,%0":"=r" (v):"m"(*p));
  44     return v;
  45 }
  46
  47 uint32_t get_32_sl(const uint32_t * p)
  48 {
  49     uint32_t v;
  50
  51     p = set_fs_sl(p);
  52     asm volatile("movl %%fs:%1,%0":"=r" (v):"m"(*p));
  53     return v;
  54 }
  55
  56 #if 0                           /* unused */
  57 uint64_t get_64_sl(const uint64_t * p)
  58 {
  59     uint32_t v0, v1;
  60     const uint32_t *pp = (const uint32_t *)set_fs_sl(p);
  61
  62     asm volatile("movl %%fs:%1,%0" : "=r" (v0) : "m" (pp[0]));
  63     asm volatile("movl %%fs:%1,%0" : "=r" (v1) : "m" (pp[1]));
  64     return v0 + ((uint64_t)v1 << 32);
  65 }
  66 #endif
  67
  68 #if 0                           /* unused */
  69 void set_8_sl(uint8_t * p, uint8_t v)
  70 {
  71     p = set_fs_sl(p);
  72     asm volatile("movb %1,%%fs:%0":"=m" (*p):"qi"(v));
  73 }
  74 #endif
  75
  76 void set_16_sl(uint16_t * p, uint16_t v)
  77 {
  78     p = set_fs_sl(p);
  79     asm volatile("movw %1,%%fs:%0":"=m" (*p):"ri"(v));
  80 }
  81
  82 void set_32_sl(uint32_t * p, uint32_t v)
  83 {
  84     p = set_fs_sl(p);
  85     asm volatile("movl %1,%%fs:%0":"=m" (*p):"ri"(v));
  86 }
  87
  88 void set_64_sl(uint64_t * p, uint64_t v)
  89 {
  90     uint32_t *pp = (uint32_t *)set_fs_sl(p);
  91     asm volatile("movl %1,%%fs:%0" : "=m" (pp[0]) : "ri"((uint32_t)v));
  92     asm volatile("movl %1,%%fs:%0" : "=m" (pp[1]) : "ri"((uint32_t)(v >> 32)));
  93 }
  94
  95 void memcpy_to_sl(void *dst, const void *src, size_t len)
  96 {
  97     uint16_t seg;
  98     uint16_t off;
  99
 100     seg = ds() + ((size_t)dst >> 4);
 101     off = (size_t)dst & 15;
 102
 103     asm volatile("pushw %%es ; "
 104                  "movw %3,%%es ; "
 105                  "rep ; movsb ; "
 106                  "popw %%es"
 107                  : "+D" (off), "+S" (src), "+c" (len)
 108                  : "r" (seg)
 109                  : "memory");
 110 }
 111
 112 void memcpy_from_sl(void *dst, const void *src, size_t len)
 113 {
 114     uint16_t seg;
 115     uint16_t off;
 116
 117     seg = ds() + ((size_t)src >> 4);
 118     off = (size_t)src & 15;
 119
 120     asm volatile("pushw %%ds ; "
 121                  "movw %3,%%ds ; "
 122                  "rep ; movsb ; "
 123                  "popw %%ds"
 124                  : "+D" (dst), "+S" (off), "+c" (len)
 125                  : "r" (seg)
 126                  : "memory");
 127 }
 128
 129 void memset_sl(void *dst, int c, size_t len)
 130 {
 131     uint16_t seg;
 132     uint16_t off;
 133
 134     seg = ds() + ((size_t)dst >> 4);
 135     off = (size_t)dst & 15;
 136
 137     asm volatile("pushw %%es ; "
 138                  "movw %3,%%es ; "
 139                  "rep ; stosb ; "
 140                  "popw %%es"
 141                  : "+D" (off), "+c" (len)
 142                  : "a" (c), "r" (seg)
 143                  : "memory");
 144 }