On Wed, Nov 12, 2014 at 10:07 AM, Jan Dolezal <dolez...@fel.cvut.cz> wrote:
> ---
> cpukit/score/cpu/i386/cpu_asm.S | 63
> ++++++++++++++++++++++++++++++++
> cpukit/score/cpu/i386/rtems/score/i386.h | 29 +++++++++++++++
> 2 files changed, 92 insertions(+)
>
> diff --git a/cpukit/score/cpu/i386/cpu_asm.S b/cpukit/score/cpu/i386/cpu_asm.S
> index 9b39567..c9e366d 100644
> --- a/cpukit/score/cpu/i386/cpu_asm.S
> +++ b/cpukit/score/cpu/i386/cpu_asm.S
> @@ -327,6 +327,69 @@ SYM (i386_Physical_to_logical):
> movl ecx,eax /* eax = ecx */
> ret
>
> +/*
> + * void *i386_Real_mode_ptr_to_physical(
> + * void *ptr
> + * );
> + *
> + * Returns thirty-two bit physical address for segment:offset realmode
> pointer.
> + */
> +
I suggest using the names i386_Real_to_physical() and
i386_Physical_to_real() to be consistent with other functions like
this in the same code.
> +.set RM_PTR_ARG, 4
> +
> + PUBLIC (i386_Real_mode_ptr_to_physical)
> +
> +SYM (i386_Real_mode_ptr_to_physical):
> + movl RM_PTR_ARG(esp),eax
> + xorl ecx, ecx
> + movw ax, cx
> + shrl $12, eax
> + andl $0xFFFF0, eax
> + addl ecx, eax
> + ret
> +
My x86 assembly is not good enough to verify the following code. Joel?
> +/*
> + * int i386_Physical_to_real_mode_ptr(
> + * void *address,
> + * unsigned short *segment,
> + * unsigned short *offset
> + * );
> + *
> + * Fills segment:offest realmode pointer counted from thirty-two bit
> physical
> + * address.
> + * Returns 0 if unconvertible, 1 if successfuly converted.
> + */
> +
> +.set RM_PTR_SEG_ARG, 8
> +.set RM_PTR_OFF_ARG, 12
> +
> + PUBLIC (i386_Physical_to_real_mode_ptr)
> +
> +SYM (i386_Physical_to_real_mode_ptr):
> + movl RM_PTR_ARG(esp),eax
> + cmpl $0x10FFF0, eax
> + js cvtbl
> + movl $0, eax
> + ret
> +cvtbl: cmpl $0x100000, eax
> + js lowmem
> + subl $0xFFFF0, eax
> + movl RM_PTR_OFF_ARG(esp), ecx
> + movw ax, (ecx)
> + movl RM_PTR_SEG_ARG(esp), ecx
> + movw $0xFFFF, (ecx)
> + movl $1, eax
> + ret
> +lowmem: movl eax, edx
> + and $0xF, ax
> + movl RM_PTR_OFF_ARG(esp), ecx
> + movw ax, (ecx)
> + shrl $4, edx
> + movl RM_PTR_SEG_ARG(esp), ecx
> + movw dx, (ecx)
> + movl $1, eax
> + ret
> +
> END_CODE
>
> END
> diff --git a/cpukit/score/cpu/i386/rtems/score/i386.h
> b/cpukit/score/cpu/i386/rtems/score/i386.h
> index 57569fc..a59e0cf 100644
> --- a/cpukit/score/cpu/i386/rtems/score/i386.h
> +++ b/cpukit/score/cpu/i386/rtems/score/i386.h
> @@ -186,6 +186,35 @@ void *i386_Physical_to_logical(
> );
>
> /*
> + * i386_Real_mode_ptr_to_physical
> + *
> + * Converts real mode pointer {segment, offset} to physical address.
> + */
> +void *i386_Real_mode_ptr_to_physical(
> + void *ptr
> +);
> +
> +/*
> + * i386_Physical_to_real_mode_ptr
> + * Retreives real mode pointer elements {segmnet, offset} from physical
> address
> + * Function returns the highest segment (base) address possible.
> + * Example: input address - 0x4B3A2
> + * output segment - 0x4B3A
> + * offset - 0x2
> + * input address - 0x10F12E
> + * output segment - 0xFFFF
> + * offset - 0xF13E
> + *
> + * return 0 address not convertible, must be less than 0x10FFEF
> + * 1 segment and offset extracted
> + */
> +int i386_Physical_to_real_mode_ptr(
> + void *address,
> + unsigned short *segment,
> + unsigned short *offset
> +);
> +
> +/*
> * "Simpler" names for a lot of the things defined in this file
> */
>
> --
> 1.9.1
>
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