[reactos] 02/03: [NTOS:KE] Use bitfield structure for x86 CPU signature in EAX register

[Marcus Boillat]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=00b3e4bc689519d67a81b5...

commit 00b3e4bc689519d67a81b59a8dad8dfe5fafdb5d
Author:     Marcus Boillat [e-mail]
AuthorDate: Sat May 7 23:27:25 2022 +0200
Commit:     Stanislav Motylkov [e-mail]
CommitDate: Mon May 9 21:50:24 2022 +0300

[NTOS:KE] Use bitfield structure for x86 CPU signature in EAX register

This makes code a lot more readable. CORE-17974
---
 ntoskrnl/ke/amd64/cpu.c | 29 +++++++++++++++++++++--------
 ntoskrnl/ke/i386/cpu.c  | 29 +++++++++++++++++++++--------
 2 files changed, 42 insertions(+), 16 deletions(-)

diff --git a/ntoskrnl/ke/amd64/cpu.c b/ntoskrnl/ke/amd64/cpu.c
index cbce873f619..4ed7e5470fe 100644
--- a/ntoskrnl/ke/amd64/cpu.c
+++ b/ntoskrnl/ke/amd64/cpu.c
@@ -35,6 +35,21 @@ static const CHAR CmpIntelID[]       = "GenuineIntel";
 static const CHAR CmpAmdID[]         = "AuthenticAMD";
 static const CHAR CmpCentaurID[]     = "CentaurHauls";

+typedef union _CPU_SIGNATURE
+{
+    struct
+    {
+        ULONG Step : 4;
+        ULONG Model : 4;
+        ULONG Family : 4;
+        ULONG Unused : 4;
+        ULONG ExtendedModel : 4;
+        ULONG ExtendedFamily : 8;
+        ULONG Unused2 : 4;
+    };
+    ULONG AsULONG;
+} CPU_SIGNATURE;
+
 /* FUNCTIONS *****************************************************************/

ULONG
@@ -82,6 +97,7 @@ NTAPI
 KiSetProcessorType(VOID)
 {
     CPU_INFO CpuInfo;
+    CPU_SIGNATURE CpuSignature;
     ULONG Stepping, Type;

/* Do CPUID 1 now */
@@ -89,17 +105,14 @@ KiSetProcessorType(VOID)

/*
      * Get the Stepping and Type. The stepping contains both the
-     * Model and the Step, while the Type contains the returned Type.
-     * We ignore the family.
+     * Model and the Step, while the Type contains the returned Family.
      *
      * For the stepping, we convert this: zzzzzzxy into this: x0y
      */
-    Stepping = CpuInfo.Eax & 0xF0;
-    Stepping <<= 4;
-    Stepping += (CpuInfo.Eax & 0xFF);
-    Stepping &= 0xF0F;
-    Type = CpuInfo.Eax & 0xF00;
-    Type >>= 8;
+    CpuSignature.AsULONG = CpuInfo.Eax;
+    Stepping = CpuSignature.Model;
+    Stepping = (Stepping << 8) | CpuSignature.Step;
+    Type = CpuSignature.Family;

/* Save them in the PRCB */
     KeGetCurrentPrcb()->CpuID = TRUE;
diff --git a/ntoskrnl/ke/i386/cpu.c b/ntoskrnl/ke/i386/cpu.c
index 4a53f407800..711070eeb07 100644
--- a/ntoskrnl/ke/i386/cpu.c
+++ b/ntoskrnl/ke/i386/cpu.c
@@ -60,6 +60,21 @@ static const CHAR CmpTransmetaID[]   = "GenuineTMx86";
 static const CHAR CmpCentaurID[]     = "CentaurHauls";
 static const CHAR CmpRiseID[]        = "RiseRiseRise";

+typedef union _CPU_SIGNATURE
+{
+    struct
+    {
+        ULONG Step : 4;
+        ULONG Model : 4;
+        ULONG Family : 4;
+        ULONG Unused : 4;
+        ULONG ExtendedModel : 4;
+        ULONG ExtendedFamily : 8;
+        ULONG Unused2 : 4;
+    };
+    ULONG AsULONG;
+} CPU_SIGNATURE;
+
 /* SUPPORT ROUTINES FOR MSVC COMPATIBILITY ***********************************/

/* NSC/Cyrix CPU configuration register index */
@@ -143,6 +158,7 @@ NTAPI
 KiSetProcessorType(VOID)
 {
     CPU_INFO CpuInfo;
+    CPU_SIGNATURE CpuSignature;
     ULONG Stepping, Type;

/* Do CPUID 1 now */
@@ -150,17 +166,14 @@ KiSetProcessorType(VOID)

/*
      * Get the Stepping and Type. The stepping contains both the
-     * Model and the Step, while the Type contains the returned Type.
-     * We ignore the family.
+     * Model and the Step, while the Type contains the returned Family.
      *
      * For the stepping, we convert this: zzzzzzxy into this: x0y
      */
-    Stepping = CpuInfo.Eax & 0xF0;
-    Stepping <<= 4;
-    Stepping += (CpuInfo.Eax & 0xFF);
-    Stepping &= 0xF0F;
-    Type = CpuInfo.Eax & 0xF00;
-    Type >>= 8;
+    CpuSignature.AsULONG = CpuInfo.Eax;
+    Stepping = CpuSignature.Model;
+    Stepping = (Stepping << 8) | CpuSignature.Step;
+    Type = CpuSignature.Family;

/* Save them in the PRCB */
     KeGetCurrentPrcb()->CpuID = TRUE;