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 #include <inttypes.h>
   9 #include <string.h>
  10 #include <stddef.h>
  11 #include <stdlib.h>
  12
  13 #include "syslxint.h"
  14 #include "mystuff.h"
  15
  16 static inline void *set_fs_sl(const void *p)
  17 {
  18     uint16_t seg;
  19
  20     seg = ds() + ((size_t) p >> 4);
  21     set_fs(seg);
  22     return (void *)((size_t) p & 0xf);
  23 }
  24
  25 #if 0                           /* unused */
  26 uint8_t get_8_sl(const uint8_t * p)
  27 {
  28     uint8_t v;
  29
  30     p = set_fs_sl(p);
  31     asm volatile("movb %%fs:%1,%0":"=q" (v):"m"(*p));
  32     return v;
  33 }
  34 #endif
  35
  36 uint16_t get_16_sl(const uint16_t * p)
  37 {
  38     uint16_t v;
  39
  40     p = set_fs_sl(p);
  41     asm volatile("movw %%fs:%1,%0":"=r" (v):"m"(*p));
  42     return v;
  43 }
  44
  45 uint32_t get_32_sl(const uint32_t * p)
  46 {
  47     uint32_t v;
  48
  49     p = set_fs_sl(p);
  50     asm volatile("movl %%fs:%1,%0":"=r" (v):"m"(*p));
  51     return v;
  52 }
  53
  54 #if 0                           /* unused */
  55 uint64_t get_64_sl(const uint64_t * p)
  56 {
  57     uint32_t v0, v1;
  58     const uint32_t *pp = (const uint32_t *)set_fs_sl(p);
  59
  60     asm volatile("movl %%fs:%1,%0" : "=r" (v0) : "m" (pp[0]));
  61     asm volatile("movl %%fs:%1,%0" : "=r" (v1) : "m" (pp[1]));
  62     return v0 + ((uint64_t)v1 << 32);
  63 }
  64 #endif
  65
  66 #if 0                           /* unused */
  67 void set_8_sl(uint8_t * p, uint8_t v)
  68 {
  69     p = set_fs_sl(p);
  70     asm volatile("movb %1,%%fs:%0":"=m" (*p):"qi"(v));
  71 }
  72 #endif
  73
  74 void set_16_sl(uint16_t * p, uint16_t v)
  75 {
  76     p = set_fs_sl(p);
  77     asm volatile("movw %1,%%fs:%0":"=m" (*p):"ri"(v));
  78 }
  79
  80 void set_32_sl(uint32_t * p, uint32_t v)
  81 {
  82     p = set_fs_sl(p);
  83     asm volatile("movl %1,%%fs:%0":"=m" (*p):"ri"(v));
  84 }
  85
  86 void set_64_sl(uint64_t * p, uint64_t v)
  87 {
  88     uint32_t *pp = (uint32_t *)set_fs_sl(p);
  89     asm volatile("movl %1,%%fs:%0" : "=m" (pp[0]) : "ri"((uint32_t)v));
  90     asm volatile("movl %1,%%fs:%0" : "=m" (pp[1]) : "ri"((uint32_t)(v >> 32)));
  91 }
  92
  93 void memcpy_to_sl(void *dst, const void *src, size_t len)
  94 {
  95     uint16_t seg;
  96     uint16_t off;
  97
  98     seg = ds() + ((size_t)dst >> 4);
  99     off = (size_t)dst & 15;
 100
 101     asm volatile("pushw %%es ; "
 102                  "movw %3,%%es ; "
 103                  "rep ; movsb ; "
 104                  "popw %%es"
 105                  : "+D" (off), "+S" (src), "+c" (len)
 106                  : "r" (seg)
 107                  : "memory");
 108 }
 109
 110 void memcpy_from_sl(void *dst, const void *src, size_t len)
 111 {
 112     uint16_t seg;
 113     uint16_t off;
 114
 115     seg = ds() + ((size_t)src >> 4);
 116     off = (size_t)src & 15;
 117
 118     asm volatile("pushw %%ds ; "
 119                  "movw %3,%%ds ; "
 120                  "rep ; movsb ; "
 121                  "popw %%ds"
 122                  : "+D" (dst), "+S" (off), "+c" (len)
 123                  : "r" (seg)
 124                  : "memory");
 125 }