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Clean up from Aleksey Romanov (Quality Quorum <qqi@world.std.com>).

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Here are his comments:

  I removed all unnecessary stuff from start16.s - setting idt and
  setting 16-bit stack using .code32 istructions.
This commit is contained in:
Joel Sherrill
1998-06-25 18:42:30 +00:00
parent 7252f65668
commit d13b247131
1 changed files with 3 additions and 26 deletions
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29
c/src/lib/libbsp/i386/pc386/start/start16.s
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@@ -33,13 +33,6 @@
.set HDROFF, 0x24 # offset into bin2boot header of start32 addr .set HDROFF, 0x24 # offset into bin2boot header of start32 addr
.set STACKOFF, 0x200-0x10 # offset to load into %esp, from start of image .set STACKOFF, 0x200-0x10 # offset to load into %esp, from start of image
/*----------------------------------------------------------------------------+
| A Descriptor table register has the following format:
+----------------------------------------------------------------------------*/
.set DTR_LIMIT, 0 # offset of two byte limit
.set DTR_BASE, 2 # offset of four byte base address
.set DTR_SIZE, 6 # size of DTR register
/*----------------------------------------------------------------------------+ /*----------------------------------------------------------------------------+
| CODE section | CODE section
@@ -61,13 +54,6 @@ _start16:
movw %ax, %es # movw %ax, %es #
movw %ax, %ss # movw %ax, %ss #
.code32
movl $STACKOFF, %esp # set stack pointer
movl $STACKOFF, %ebp #
.code16
#if defined(RTEMS_VIDEO_80x50) #if defined(RTEMS_VIDEO_80x50)
/*---------------------------------------------------------------------+ /*---------------------------------------------------------------------+
@@ -94,7 +80,6 @@ _start16:
+---------------------------------------------------------------------*/ +---------------------------------------------------------------------*/
lgdt gdtptr - start16 # load Global Descriptor Table lgdt gdtptr - start16 # load Global Descriptor Table
lidt idtptr - start16 # load Interrupt Descriptor Table
movl %cr0, %eax movl %cr0, %eax
orl $CR0_PE, %eax orl $CR0_PE, %eax
@@ -112,8 +97,8 @@ _start16:
movl %ax, %ds movl %ax, %ds
movl %ax, %es movl %ax, %es
movl %ax, %ss movl %ax, %ss
addl $start16, %esp # fix up stack pointer movl $start16 + STACKOFF, %esp # set up stack pointer
addl $start16, %ebp # fix up stack pointer addl $start16 + STACKOFF, %ebp # set up stack pointer
/*---------------------------------------------------------------------+ /*---------------------------------------------------------------------+
| we have to enable A20 in order to access memory above 1MByte | we have to enable A20 in order to access memory above 1MByte
@@ -174,7 +159,7 @@ no_output:
* GLOBAL DESCRIPTOR TABLE * * GLOBAL DESCRIPTOR TABLE *
**************************/ **************************/
.align 4 .p2align 4
gdtptr: gdtptr:
/* we use the NULL descriptor to store the GDT pointer - a trick quite /* we use the NULL descriptor to store the GDT pointer - a trick quite
nifty due to: Robert Collins (rcollins@x86.org) */ nifty due to: Robert Collins (rcollins@x86.org) */
@@ -192,11 +177,3 @@ gdtptr:
.set gdtlen, . - gdtptr # length of GDT .set gdtlen, . - gdtptr # length of GDT
/*************************************
* INTERRUPT DESCRIPTOR TABLE POINTER *
*************************************/
.align 4
idtptr:
.word 0x07ff # limit at maximum (allows all 256 interrupts)
.word 0, 0 # base at 0