From e611b132f9b8abe35b362e5870b74bce94a1e58e Mon Sep 17 00:00:00 2001
From: Adam <you@example.com>
Date: Sat, 16 May 2020 20:51:50 -0700
Subject: initial commit

---
 private/ntos/nthals/halx86/i386/ixenvirv.c | 183 +++++++++++++++++++++++++++++
 1 file changed, 183 insertions(+)
 create mode 100644 private/ntos/nthals/halx86/i386/ixenvirv.c

(limited to 'private/ntos/nthals/halx86/i386/ixenvirv.c')

diff --git a/private/ntos/nthals/halx86/i386/ixenvirv.c b/private/ntos/nthals/halx86/i386/ixenvirv.c
new file mode 100644
index 000000000..62bdccf01
--- /dev/null
+++ b/private/ntos/nthals/halx86/i386/ixenvirv.c
@@ -0,0 +1,183 @@
+/*++
+
+Copyright (c) 1992  Microsoft Corporation
+
+Module Name:
+
+    ixenvirv.c
+
+Abstract:
+
+    This module implements the HAL get and set environment variable routines
+    for a x86 system.
+
+    Note that this particular implementation only supports the LastKnownGood
+    environment variable.  This is done by using the Daylight Savings Time
+    bit in the Real Time Clock NVRAM.  (Not pretty, but it's all we've got)
+
+    Attempts to read or write any environment variable other than
+    LastKnownGood will fail.
+
+Author:
+
+    John Vert (jvert) 22-Apr-1992
+
+Environment:
+
+    Kernel mode
+
+Revision History:
+
+--*/
+
+#include "halp.h"
+#include "arc.h"
+#include "arccodes.h"
+#include "string.h"
+
+#define CMOS_CONTROL_PORT ((PUCHAR)0x70)
+#define CMOS_DATA_PORT    ((PUCHAR)0x71)
+#define CMOS_STATUS_B     0x0B
+#define CMOS_DAYLIGHT_BIT 1
+
+
+ARC_STATUS
+HalGetEnvironmentVariable (
+    IN PCHAR Variable,
+    IN USHORT Length,
+    OUT PCHAR Buffer
+    )
+
+/*++
+
+Routine Description:
+
+    This function locates an environment variable and returns its value.
+
+    The only environment variable this implementation supports is
+    "LastKnownGood"  It uses the Daylight Savings Time bit in the Real
+    TimeClock to indicate the state (TRUE/FALSE only) of this environment
+    variable.
+
+Arguments:
+
+    Variable - Supplies a pointer to a zero terminated environment variable
+        name.
+
+    Length - Supplies the length of the value buffer in bytes.
+
+    Buffer - Supplies a pointer to a buffer that receives the variable value.
+
+Return Value:
+
+    ESUCCESS is returned if the enviroment variable is located. Otherwise,
+    ENOENT is returned.
+
+--*/
+
+{
+    UCHAR StatusByte;
+
+    UNREFERENCED_PARAMETER( Length );
+    UNREFERENCED_PARAMETER( Buffer );
+
+    if (_stricmp(Variable, "LastKnownGood") != 0) {
+        return ENOENT;
+    }
+
+    //
+    // Read the Daylight Savings Bit out of the RTC to determine whether
+    // the LastKnownGood environment variable is TRUE or FALSE.
+    //
+
+    HalpAcquireCmosSpinLock();
+    WRITE_PORT_UCHAR(CMOS_CONTROL_PORT, CMOS_STATUS_B);
+    StatusByte = READ_PORT_UCHAR(CMOS_DATA_PORT);
+    HalpReleaseCmosSpinLock ();
+
+    if (StatusByte & CMOS_DAYLIGHT_BIT) {
+        strncpy(Buffer, "TRUE", Length);
+    } else {
+        strncpy(Buffer, "FALSE", Length);
+    }
+
+    return ESUCCESS;
+}
+
+ARC_STATUS
+HalSetEnvironmentVariable (
+    IN PCHAR Variable,
+    IN PCHAR Value
+    )
+
+/*++
+
+Routine Description:
+
+    This function creates an environment variable with the specified value.
+
+    The only environment variable this implementation supports is
+    "LastKnownGood"  It uses the Daylight Savings Time bit in the Real
+    TimeClock to indicate the state (TRUE/FALSE only) of this environment
+    variable.
+
+Arguments:
+
+    Variable - Supplies a pointer to an environment variable name.
+
+    Value - Supplies a pointer to the environment variable value.
+
+Return Value:
+
+    ESUCCESS is returned if the environment variable is created. Otherwise,
+    ENOMEM is returned.
+
+--*/
+
+{
+    UCHAR StatusByte;
+
+    if (_stricmp(Variable, "LastKnownGood") != 0) {
+        return ENOMEM;
+    }
+
+    if (_stricmp(Value, "TRUE") == 0) {
+
+        HalpAcquireCmosSpinLock();
+        //
+        // Turn Daylight Savings Bit on.
+        //
+        WRITE_PORT_UCHAR(CMOS_CONTROL_PORT, CMOS_STATUS_B);
+        StatusByte = READ_PORT_UCHAR(CMOS_DATA_PORT);
+
+        StatusByte |= CMOS_DAYLIGHT_BIT;
+
+        WRITE_PORT_UCHAR(CMOS_CONTROL_PORT, CMOS_STATUS_B);
+        WRITE_PORT_UCHAR(CMOS_DATA_PORT, StatusByte);
+
+        HalpReleaseCmosSpinLock();
+
+    } else if (_stricmp(Value, "FALSE") == 0) {
+
+        HalpAcquireCmosSpinLock();
+
+        //
+        // Turn Daylight Savings Bit off.
+        //
+
+        WRITE_PORT_UCHAR(CMOS_CONTROL_PORT, CMOS_STATUS_B);
+        StatusByte = READ_PORT_UCHAR(CMOS_DATA_PORT);
+
+        StatusByte &= ~CMOS_DAYLIGHT_BIT;
+
+        WRITE_PORT_UCHAR(CMOS_CONTROL_PORT, CMOS_STATUS_B);
+        WRITE_PORT_UCHAR(CMOS_DATA_PORT, StatusByte);
+
+        HalpReleaseCmosSpinLock();
+
+    } else {
+        return(ENOMEM);
+    }
+
+    return ESUCCESS;
+}
-- 
cgit v1.2.3