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// TITLE("Floating Point Control")//++//// Copyright (c) 1992 Digital Equipment Corporation//// Module Name://// fpctrl.s//// Abstract://// This module implements routines that control floating point// operations.//// Author://// Thomas Van Baak (tvb) 31-Aug-1992//// Environment://// Any mode.//// Revision History:////--
#include "ksalpha.h"
//// Define call frame used to exchange a floating point and integer register.//
.struct 0FpCr: .space 8 // fpcr value .space 8 // ensure 16-byte stack alignmentFpFrameLength: // length of stack frame SBTTL("Get Hardware Floating Point Control Register")//++//// ULONGLONG// _get_fpcr (// VOID// )//// Routine Description://// This function obtains the current FPCR value.//// Arguments://// None.//// Return Value://// The current value of the FPCR is returned as the function value.////--
NESTED_ENTRY(_get_fpcr, FpFrameLength, ra)
lda sp, -FpFrameLength(sp) // allocate stack frame
PROLOGUE_END
excb // wait for all pending traps mf_fpcr f0, f0, f0 // get current fpcr excb // block against new traps stt f0, FpCr(sp) // store floating register in order to ldq v0, FpCr(sp) // load integer register with fpcr
lda sp, FpFrameLength(sp) // deallocate stack frame ret zero, (ra) // return
.end _get_fpcr SBTTL("Set Hardware Floating Point Control Register")//++//// VOID// _set_fpcr (// ULONGLONG FpcrValue// )//// Routine Description://// This function sets a new value in the FPCR.//// Arguments://// FpcrValue (a0) - Supplies the new value for the FPCR.//// Return Value://// None.////--
NESTED_ENTRY(_set_fpcr, FpFrameLength, ra)
lda sp, -FpFrameLength(sp) // allocate stack frame
PROLOGUE_END
stq a0, FpCr(sp) // store integer register in order to ldt f0, FpCr(sp) // load floating register with fpcr excb // wait for all pending traps mt_fpcr f0, f0, f0 // set new fpcr excb // block against new traps
lda sp, FpFrameLength(sp) // deallocate stack frame ret zero, (ra) // return
.end _set_fpcr SBTTL("Get Software Floating Point Control and Status Register")//++//// ULONG// _get_softfpcr (// VOID// )//// Routine Description://// This function obtains the current software FPCR value.//// Arguments://// None.//// Return Value://// The current value of the software FPCR is returned as the function value.////--
LEAF_ENTRY(_get_softfpcr)
GET_THREAD_ENVIRONMENT_BLOCK // get Teb address in v0 ldl v0, TeSoftFpcr(v0) // get current software fpcr value ret zero, (ra) // return
.end _get_softfpcr SBTTL("Set Software Floating Point Control and Status Register")//++//// VOID// _set_softfpcr (// ULONG SoftFpcrValue// )//// Routine Description://// This function sets a new value in the software FPCR.//// Arguments://// SoftFpcrValue (a0) - Supplies the new value for the software FPCR.//// Return Value://// None.////--
LEAF_ENTRY(_set_softfpcr)
GET_THREAD_ENVIRONMENT_BLOCK // get Teb address in v0 stl a0, TeSoftFpcr(v0) // store new software fpcr value ret zero, (ra) // return
.end _set_softfpcr SBTTL("Set New Floating Control Register Value")//++//// ULONG// _ctrlfp (// IN ULONG newctrl,// IN ULONG mask// )//// Routine Description://// For Alpha AXP this function sets nothing. It returns the current// rounding mode and the current IEEE exception disable mask in the// fp32 internal control word format.//// Arguments://// newctrl (a0) - Supplies the new control bits to be set.//// mask (a1) - Supplies the mask of bits to be set.//// Return Value://// oldctrl (v0) - Returns the old value of the control bits.//////--
NESTED_ENTRY(_ctrlfp, FpFrameLength, ra)
lda sp, -FpFrameLength(sp) // allocate stack frame
PROLOGUE_END
//// Get the dynamic rounding mode from the FPCR.//
excb // wait for all pending traps mf_fpcr f0, f0, f0 // get current fpcr excb // block against new traps stt f0, FpCr(sp) // store floating register in order to ldq t0, FpCr(sp) // load integer register with fpcr
srl t0, 58, t0 // shift rounding mode to low end and t0, 0x3, t0 // isolate rounding mode bits sll t0, 58 - 32, t0 // shift to internal cw format
//// Get the IEEE exception mask bits and status bits from the software FPCR.//
GET_THREAD_ENVIRONMENT_BLOCK // get Teb address in v0 ldl v0, TeSoftFpcr(v0) // get current software fpcr value xor v0, 0x3e, v0 // convert enable bits to disable bits or v0, t0, v0 // merge with current rounding mode
lda sp, FpFrameLength(sp) // deallocate stack frame ret zero, (ra) // return
.end _ctrlfp SBTTL("Get IEEE Sticky Status Bits")//++//// ULONG// _statfp (// VOID// )//// Routine Description://// This function gets the IEEE sticky status bits from the software FPCR.//// Arguments://// None.//// Return Value://// The current value of the status word is returned as the function value.////--
LEAF_ENTRY(_statfp)
GET_THREAD_ENVIRONMENT_BLOCK // get Teb address in v0 ldl v0, TeSoftFpcr(v0) // get current software fpcr value ret zero, (ra) // return
.end _statfp SBTTL("Clear IEEE Sticky Status Bits")//++//// ULONG// _clrfp (// VOID// )//// Routine Description://// This function clears the IEEE sticky status bits in the software FPCR.//// Arguments://// None.//// Return Value://// The previous value of the status word is returned as the function value.////--
LEAF_ENTRY(_clrfp)
GET_THREAD_ENVIRONMENT_BLOCK // get Teb address in v0 ldl t0, TeSoftFpcr(v0) // get current software fpcr value bic t0, 0x3e0000, t1 // clear status bits stl t1, TeSoftFpcr(v0) // store new software fpcr value mov t0, v0 // get previous value ret zero, (ra) // return
.end _clrfp SBTTL("Set IEEE Sticky Status Bits")//++//// VOID// _set_statfp (// IN ULONG sw// )//// Routine Description://// This function sets a IEEE sticky status bit in the software FPCR.//// Arguments://// sw (a0) - Supplies the status bits to be set.//// Return Value://// None.////--
LEAF_ENTRY(_set_statfp)
GET_THREAD_ENVIRONMENT_BLOCK // get Teb address in v0 ldl t0, TeSoftFpcr(v0) // get current software fpcr value or t0, a0, t0 // set status bit(s) stl t0, TeSoftFpcr(v0) // store new software fpcr value ret zero, (ra) // return
.end _set_statfp SBTTL("Convert Signal NaN to Quiet NaN")//++//// double// _nan2qnan (// IN double x// )//// Routine Description://// This function converts a signaling NaN to a quiet NaN without causing// a hardware trap.//// Arguments://// x (f16) - Supplies the signal NaN value to be converted.//// Return Value://// The quiet NaN value is returned as the function value.////-- NESTED_ENTRY(_nan2qnan, FpFrameLength, ra)
lda sp, -FpFrameLength(sp) // allocate stack frame
PROLOGUE_END
stt f16, FpCr(sp) // store floating register in order to ldq t0, FpCr(sp) // load integer register ldiq t1, (1 << 51) // get NaN bit or t0, t1, t0 // convert NaN to QNaN stq t0, FpCr(sp) // store integer register in order to ldt f0, FpCr(sp) // load floating register
lda sp, FpFrameLength(sp) // deallocate stack frame ret zero, (ra) // return
.end _nan2qnan
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