base/dispatch.c: Add documentation for some internal functions.

[catacomb] / base / dispatch.c

diff --git a/base/dispatch.c b/base/dispatch.c
index 87d41b3..4b5e17a 100644 (file)
--- a/base/dispatch.c
+++ b/base/dispatch.c
@@ -37,13 +37,14 @@
 
 #include "dispatch.h"
 
-/*----- Main code ---------------------------------------------------------*/
+/*----- Intel x86/AMD64 feature probing -----------------------------------*/
 
 #ifdef CPUFAM_X86
 
 #define EFLAGS_ID (1u << 21)
 #define CPUID1D_SSE2 (1u << 26)
 #define CPUID1D_FXSR (1u << 24)
+#define CPUID1C_AESNI (1u << 25)
 
 struct cpuid { unsigned a, b, c, d; };
 
@@ -100,6 +101,15 @@ static void cpuid(struct cpuid *cc, unsigned a, unsigned c)
 static unsigned cpuid_maxleaf(void)
   { struct cpuid c; cpuid(&c, 0, 0); return (c.a); }
 
+/* --- @cpuid_features_p@ --- *
+ *
+ * Arguments:  @unsigned dbits@ = bits to check in EDX
+ *             @unsigned cbits@ = bits to check in ECX
+ *
+ * Returns:    Nonzero if all the requested bits are set in the CPUID result
+ *             on leaf 1.
+ */
+
 static int cpuid_features_p(unsigned dbits, unsigned cbits)
 {
   struct cpuid c;
@@ -108,6 +118,14 @@ static int cpuid_features_p(unsigned dbits, unsigned cbits)
   return ((c.d & dbits) == dbits && (c.c & cbits) == cbits);
 }
 
+/* --- @xmm_registers_available_p@ --- *
+ *
+ * Arguments:  ---
+ *
+ * Returns:    Nonzero if the operating system has made the XMM registers
+ *             available for use.
+ */
+
 static int xmm_registers_available_p(void)
 {
 #ifdef __GNUC__
@@ -134,6 +152,8 @@ static int xmm_registers_available_p(void)
 
 #endif
 
+/*----- External interface ------------------------------------------------*/
+
 /* --- @check_env@ --- *
  *
  * Arguments:  @const char *ftok@ = feature token
@@ -196,6 +216,11 @@ int cpu_feature_p(int feat)
       return (xmm_registers_available_p() &&
              cpuid_features_p(CPUID1D_SSE2, 0));
     }
+    case CPUFEAT_X86_AESNI: {
+      check_env("x86:aesni");
+      return (xmm_registers_available_p() &&
+             cpuid_features_p(CPUID1D_SSE2, CPUID1C_AESNI));
+    }
 #endif
     default:
       return (0);