EmbeddedPkg: Extend NvVarStoreFormattedLib LIBRARY_CLASS

[mirror_edk2.git] / StdLib / LibC / Main / X64 / fpu_rmode.asm

;------------------------------------------------------------------------------\r
; Return the current FPU rounding mode.\r
;\r
; MASM implementation of the flt_rounds function from NetBSD.\r
;\r
; Copyright (c) 2010, Intel Corporation. All rights reserved.<BR>\r
; This program and the accompanying materials\r
; are licensed and made available under the terms and conditions of the BSD License\r
; which accompanies this distribution.  The full text of the license may be found at\r
; http://opensource.org/licenses/bsd-license.php.\r
;\r
; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
;\r
;------------------------------------------------------------------------------\r
\r
    .code\r
\r
;_map  BYTE  1     ; round to nearest\r
;      BYTE  3     ; round to negative infinity\r
;      BYTE  2     ; round to positive infinity\r
;      BYTE  0     ; round to zero\r
\r
;------------------------------------------------------------------------------\r
; int\r
; EFIAPI\r
; fpu_rmode( void );\r
;\r
; VC++ always creates space for 4 parameters on the stack, whether they are\r
; used or not.  We use one for temporary storage since the only variant of\r
; fnstcw saves to memory, NOT a register.\r
;------------------------------------------------------------------------------\r
internal_FPU_rmode    PROC\r
    fnstcw    [rsp + 8]       ; save 16-bit FPU Control Word\r
    mov       eax, [rsp + 8]  ; get the saved FPU Control Word\r
    shr       eax, 10\r
    and       rax, 3          ; index is only the LSB two bits in RAX\r
    ret                       ; Return rounding mode in RAX\r
internal_FPU_rmode    ENDP\r
\r
    END\r