Undo a90081576c94f9f54de1755188a00ccc1760549a

[openssl.git] / crypto / x86cpuid.pl

diff --git a/crypto/x86cpuid.pl b/crypto/x86cpuid.pl
index dca37e7cd265878d04a77d6dea0235add06e4c74..86772329bc7bd5a2492e59fdddb25e7901b0f6c2 100644 (file)
--- a/crypto/x86cpuid.pl
+++ b/crypto/x86cpuid.pl
@@ -168,7 +168,7 @@ for (@ARGV) { $sse2=1 if (/-DOPENSSL_IA32_SSE2/); }
        &ret    ();
 &function_end_B("OPENSSL_rdtsc");
 
-# This works in Ring 0 only [read MS-DOS+privileged DPMI host],
+# This works in Ring 0 only [read DJGPP+MS-DOS+privileged DPMI host],
 # but it's safe to call it on any [supported] 32-bit platform...
 # Just check for [non-]zero return value...
 &function_begin_B("OPENSSL_instrument_halt","EXTRN\t_OPENSSL_ia32cap_P:DWORD");
@@ -202,6 +202,41 @@ for (@ARGV) { $sse2=1 if (/-DOPENSSL_IA32_SSE2/); }
        &ret    ();
 &function_end_B("OPENSSL_instrument_halt");
 
+# Essentially there is only one use for this function. Under DJGPP:
+#
+#      #include <go32.h>
+#      ...
+#      i=OPENSSL_far_spin(_dos_ds,0x46c);
+#      ...
+# to obtain the number of spins till closest timer interrupt.
+
+&function_begin_B("OPENSSL_far_spin");
+       &pushf  ();
+       &pop    ("eax");
+       &bt     ("eax",9);
+       &jnc    (&label("nospin"));     # interrupts are disabled
+
+       &mov    ("eax",&DWP(4,"esp"));
+       &mov    ("ecx",&DWP(8,"esp"));
+       &data_word (0x90d88e1e);        # push %ds, mov %eax,%ds
+       &xor    ("eax","eax");
+       &mov    ("edx",&DWP(0,"ecx"));
+       &jmp    (&label("spin"));
+
+       &align  (16);
+&set_label("spin");
+       &inc    ("eax");
+       &cmp    ("edx",&DWP(0,"ecx"));
+       &je     (&label("spin"));
+
+       &data_word (0x1f909090);        # pop   %ds
+       &ret    ();
+
+&set_label("nospin");
+       &xor    ("eax","eax");
+       &xor    ("edx","edx");
+       &ret    ();
+&function_end_B("OPENSSL_far_spin");
 
 &function_begin_B("OPENSSL_wipe_cpu","EXTRN\t_OPENSSL_ia32cap_P:DWORD");
        &xor    ("eax","eax");