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- Patch by Carlo Bramini reviewed by lassy:
The CF must be tested when reading time because the legacy DS12x87
chip shows a condition where it's updating its time registers and if it's the
case then the call should be retried later. Now the time is valid when both CF flags for date and time are good at the same time.
It's better to send the correct value of CF with the proper field to the REGS structure instead of hoping that the flag won't be changed by compiled code.
In the Int386() function I did the fix for acquiring the status flags to send to the software interrupt.
I also think it is also a good idea to always clear the direction flag before
doing movsb/movsw/movsd in this function. Since we are working with DOS stuff,
the state of the direction register could be unknown, who knows what happens
after those INT opcodes. Afterall I don't think that adding these two "cld"
would be a big problem.
See issue #2786 for more details.

svn path=/trunk/; revision=48383
This commit is contained in:
Gabriel Ilardi 2010-07-31 21:00:40 +00:00
parent a5101cce25
commit 04dc5e3fce
3 changed files with 86 additions and 58 deletions
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19
reactos/boot/freeldr/freeldr/arch/i386/int386.S
View file

@ -23,6 +23,10 @@
#define ASM #define ASM
#include <arch.h> #include <arch.h>
/* Only these flags are propagated into Int386() */
#define FLAGS_PROP (I386FLAG_CF | \
I386FLAG_ZF | \
I386FLAG_SF)
Int386_REGS: Int386_REGS:
@ -85,6 +89,7 @@ EXTERN(_Int386)
movl $Int386_REGS,%edi movl $Int386_REGS,%edi
movl Int386_regsin,%esi movl Int386_regsin,%esi
movl $0x24,%ecx movl $0x24,%ecx
cld
rep rep
movsb movsb
@ -101,6 +106,16 @@ EXTERN(_Int386)
movw %cs:Int386_gs,%ax movw %cs:Int386_gs,%ax
movw %ax,%gs /* GS register */ movw %ax,%gs /* GS register */
/* Prepare EFLAGS for recover */
pushf
movw %cs:Int386_eflags, %ax
popw %cx
andw $FLAGS_PROP, %ax
andw $~FLAGS_PROP, %cx
orw %cx, %ax
pushw %ax
/* Recover general purpose registers */
movl %cs:Int386_eax,%eax /* EAX register */ movl %cs:Int386_eax,%eax /* EAX register */
movl %cs:Int386_ebx,%ebx /* EBX register */ movl %cs:Int386_ebx,%ebx /* EBX register */
movl %cs:Int386_ecx,%ecx /* ECX register */ movl %cs:Int386_ecx,%ecx /* ECX register */
@ -109,6 +124,9 @@ EXTERN(_Int386)
movl %cs:Int386_esi,%esi /* ESI register */ movl %cs:Int386_esi,%esi /* ESI register */
movl %cs:Int386_edi,%edi /* EDI register */ movl %cs:Int386_edi,%edi /* EDI register */
/* Recover previously prepared flags */
popf
/* Do not set the flags register */ /* Do not set the flags register */
/* only return its value in regsout */ /* only return its value in regsout */
//pushl Int386_eflags //pushl Int386_eflags
@ -149,6 +167,7 @@ Int386_vector_opcode:
movl $Int386_REGS,%esi movl $Int386_REGS,%esi
movl Int386_regsout,%edi movl Int386_regsout,%edi
movl $0x24,%ecx movl $0x24,%ecx
cld
rep rep
movsb movsb

98
reactos/boot/freeldr/freeldr/arch/i386/pcrtc.c
View file

@ -27,56 +27,66 @@ PcGetTime(VOID)
static TIMEINFO TimeInfo; static TIMEINFO TimeInfo;
REGS Regs; REGS Regs;
/* Some BIOSes, such as the 1998/07/25 system ROM for (;;)
* in the Compaq Deskpro EP/SB, leave CF unchanged {
* if successful, so CF should be cleared before /* Some BIOSes, such as the 1998/07/25 system ROM
* calling this function. */ * in the Compaq Deskpro EP/SB, leave CF unchanged
__writeeflags(__readeflags() & ~EFLAGS_CF); * if successful, so CF should be cleared before
* calling this function. */
Regs.x.eflags = 0;
// __writeeflags(__readeflags() & ~EFLAGS_CF);
/* Int 1Ah AH=04h /* Int 1Ah AH=04h
* TIME - GET REAL-TIME CLOCK DATE (AT,XT286,PS) * TIME - GET REAL-TIME CLOCK DATE (AT,XT286,PS)
* *
* AH = 04h * AH = 04h
* CF clear to avoid bug * CF clear to avoid bug
* Return: * Return:
* CF clear if successful * CF clear if successful
* CH = century (BCD) * CH = century (BCD)
* CL = year (BCD) * CL = year (BCD)
* DH = month (BCD) * DH = month (BCD)
* DL = day (BCD) * DL = day (BCD)
* CF set on error * CF set on error
*/ */
Regs.b.ah = 0x04; Regs.b.ah = 0x04;
Int386(0x1A, &Regs, &Regs); Int386(0x1A, &Regs, &Regs);
TimeInfo.Year = 100 * BCD_INT(Regs.b.ch) + BCD_INT(Regs.b.cl); if (!INT386_SUCCESS(Regs)) continue;
TimeInfo.Month = BCD_INT(Regs.b.dh);
TimeInfo.Day = BCD_INT(Regs.b.dl);
/* Some BIOSes leave CF unchanged if successful, TimeInfo.Year = 100 * BCD_INT(Regs.b.ch) + BCD_INT(Regs.b.cl);
* so CF should be cleared before calling this function. */ TimeInfo.Month = BCD_INT(Regs.b.dh);
__writeeflags(__readeflags() & ~EFLAGS_CF); TimeInfo.Day = BCD_INT(Regs.b.dl);
/* Int 1Ah AH=02h /* Some BIOSes leave CF unchanged if successful,
* TIME - GET REAL-TIME CLOCK TIME (AT,XT286,PS) * so CF should be cleared before calling this function. */
* Regs.x.eflags = 0;
* AH = 02h // __writeeflags(__readeflags() & ~EFLAGS_CF);
* CF clear to avoid bug
* Return:
* CF clear if successful
* CH = hour (BCD)
* CL = minutes (BCD)
* DH = seconds (BCD)
* DL = daylight savings flag (00h standard time, 01h daylight time)
* CF set on error (i.e. clock not running or in middle of update)
*/
Regs.b.ah = 0x02;
Int386(0x1A, &Regs, &Regs);
TimeInfo.Hour = BCD_INT(Regs.b.ch); /* Int 1Ah AH=02h
TimeInfo.Minute = BCD_INT(Regs.b.cl); * TIME - GET REAL-TIME CLOCK TIME (AT,XT286,PS)
TimeInfo.Second = BCD_INT(Regs.b.dh); *
* AH = 02h
* CF clear to avoid bug
* Return:
* CF clear if successful
* CH = hour (BCD)
* CL = minutes (BCD)
* DH = seconds (BCD)
* DL = daylight savings flag (00h standard time, 01h daylight time)
* CF set on error (i.e. clock not running or in middle of update)
*/
Regs.b.ah = 0x02;
Int386(0x1A, &Regs, &Regs);
if (!INT386_SUCCESS(Regs)) continue;
TimeInfo.Hour = BCD_INT(Regs.b.ch);
TimeInfo.Minute = BCD_INT(Regs.b.cl);
TimeInfo.Second = BCD_INT(Regs.b.dh);
break;
}
return &TimeInfo; return &TimeInfo;
} }

27
reactos/boot/freeldr/freeldr/include/arch.h
View file

@ -58,6 +58,19 @@ extern ULONG gDiskReadBuffer, gFileSysBuffer;
#define EXTERN(x) .global x; x: #define EXTERN(x) .global x; x:
// Flag Masks
#define I386FLAG_CF 0x0001 // Carry Flag
#define I386FLAG_RESV1 0x0002 // Reserved - Must be 1
#define I386FLAG_PF 0x0004 // Parity Flag
#define I386FLAG_RESV2 0x0008 // Reserved - Must be 0
#define I386FLAG_AF 0x0010 // Auxiliary Flag
#define I386FLAG_RESV3 0x0020 // Reserved - Must be 0
#define I386FLAG_ZF 0x0040 // Zero Flag
#define I386FLAG_SF 0x0080 // Sign Flag
#define I386FLAG_TF 0x0100 // Trap Flag (Single Step)
#define I386FLAG_IF 0x0200 // Interrupt Flag
#define I386FLAG_DF 0x0400 // Direction Flag
#define I386FLAG_OF 0x0800 // Overflow Flag
#ifndef ASM #ifndef ASM
@ -148,20 +161,6 @@ typedef union
// specifically handles linear addresses. // specifically handles linear addresses.
int Int386(int ivec, REGS* in, REGS* out); int Int386(int ivec, REGS* in, REGS* out);
// Flag Masks
#define I386FLAG_CF 0x0001 // Carry Flag
#define I386FLAG_RESV1 0x0002 // Reserved - Must be 1
#define I386FLAG_PF 0x0004 // Parity Flag
#define I386FLAG_RESV2 0x0008 // Reserved - Must be 0
#define I386FLAG_AF 0x0010 // Auxiliary Flag
#define I386FLAG_RESV3 0x0020 // Reserved - Must be 0
#define I386FLAG_ZF 0x0040 // Zero Flag
#define I386FLAG_SF 0x0080 // Sign Flag
#define I386FLAG_TF 0x0100 // Trap Flag (Single Step)
#define I386FLAG_IF 0x0200 // Interrupt Flag
#define I386FLAG_DF 0x0400 // Direction Flag
#define I386FLAG_OF 0x0800 // Overflow Flag
// This macro tests the Carry Flag // This macro tests the Carry Flag
// If CF is set then the call failed (usually) // If CF is set then the call failed (usually)
#define INT386_SUCCESS(regs) ((regs.x.eflags & I386FLAG_CF) == 0) #define INT386_SUCCESS(regs) ((regs.x.eflags & I386FLAG_CF) == 0)