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Diffstat (limited to 'c/src/lib/libcpu/m68k/m68040/fpsp/sint.S')
| -rw-r--r-- | c/src/lib/libcpu/m68k/m68040/fpsp/sint.S | 249 |
1 files changed, 249 insertions, 0 deletions
diff --git a/c/src/lib/libcpu/m68k/m68040/fpsp/sint.S b/c/src/lib/libcpu/m68k/m68040/fpsp/sint.S new file mode 100644 index 0000000000..a9ddacb98a --- /dev/null +++ b/c/src/lib/libcpu/m68k/m68040/fpsp/sint.S @@ -0,0 +1,249 @@ +// +// $Id$ +// +// sint.sa 3.1 12/10/90 +// +// The entry point sINT computes the rounded integer +// equivalent of the input argument, sINTRZ computes +// the integer rounded to zero of the input argument. +// +// Entry points sint and sintrz are called from do_func +// to emulate the fint and fintrz unimplemented instructions, +// respectively. Entry point sintdo is used by bindec. +// +// Input: (Entry points sint and sintrz) Double-extended +// number X in the ETEMP space in the floating-point +// save stack. +// (Entry point sintdo) Double-extended number X in +// location pointed to by the address register a0. +// (Entry point sintd) Double-extended denormalized +// number X in the ETEMP space in the floating-point +// save stack. +// +// Output: The function returns int(X) or intrz(X) in fp0. +// +// Modifies: fp0. +// +// Algorithm: (sint and sintrz) +// +// 1. If exp(X) >= 63, return X. +// If exp(X) < 0, return +/- 0 or +/- 1, according to +// the rounding mode. +// +// 2. (X is in range) set rsc = 63 - exp(X). Unnormalize the +// result to the exponent $403e. +// +// 3. Round the result in the mode given in USER_FPCR. For +// sintrz, force round-to-zero mode. +// +// 4. Normalize the rounded result; store in fp0. +// +// For the denormalized cases, force the correct result +// for the given sign and rounding mode. +// +// Sign(X) +// RMODE + - +// ----- -------- +// RN +0 -0 +// RZ +0 -0 +// RM +0 -1 +// RP +1 -0 +// +// +// Copyright (C) Motorola, Inc. 1990 +// All Rights Reserved +// +// THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA +// The copyright notice above does not evidence any +// actual or intended publication of such source code. + +//SINT idnt 2,1 | Motorola 040 Floating Point Software Package + + |section 8 + +#include "fpsp.defs" + + |xref dnrm_lp + |xref nrm_set + |xref round + |xref t_inx2 + |xref ld_pone + |xref ld_mone + |xref ld_pzero + |xref ld_mzero + |xref snzrinx + +// +// FINT +// + .global sint +sint: + bfextu FPCR_MODE(%a6){#2:#2},%d1 //use user's mode for rounding +// ;implicitly has extend precision +// ;in upper word. + movel %d1,L_SCR1(%a6) //save mode bits + bras sintexc + +// +// FINT with extended denorm inputs. +// + .global sintd +sintd: + btstb #5,FPCR_MODE(%a6) + beq snzrinx //if round nearest or round zero, +/- 0 + btstb #4,FPCR_MODE(%a6) + beqs rnd_mns +rnd_pls: + btstb #sign_bit,LOCAL_EX(%a0) + bnes sintmz + bsr ld_pone //if round plus inf and pos, answer is +1 + bra t_inx2 +rnd_mns: + btstb #sign_bit,LOCAL_EX(%a0) + beqs sintpz + bsr ld_mone //if round mns inf and neg, answer is -1 + bra t_inx2 +sintpz: + bsr ld_pzero + bra t_inx2 +sintmz: + bsr ld_mzero + bra t_inx2 + +// +// FINTRZ +// + .global sintrz +sintrz: + movel #1,L_SCR1(%a6) //use rz mode for rounding +// ;implicitly has extend precision +// ;in upper word. + bras sintexc +// +// SINTDO +// +// Input: a0 points to an IEEE extended format operand +// Output: fp0 has the result +// +// Exceptions: +// +// If the subroutine results in an inexact operation, the inx2 and +// ainx bits in the USER_FPSR are set. +// +// + .global sintdo +sintdo: + bfextu FPCR_MODE(%a6){#2:#2},%d1 //use user's mode for rounding +// ;implicitly has ext precision +// ;in upper word. + movel %d1,L_SCR1(%a6) //save mode bits +// +// Real work of sint is in sintexc +// +sintexc: + bclrb #sign_bit,LOCAL_EX(%a0) //convert to internal extended +// ;format + sne LOCAL_SGN(%a0) + cmpw #0x403e,LOCAL_EX(%a0) //check if (unbiased) exp > 63 + bgts out_rnge //branch if exp < 63 + cmpw #0x3ffd,LOCAL_EX(%a0) //check if (unbiased) exp < 0 + bgt in_rnge //if 63 >= exp > 0, do calc +// +// Input is less than zero. Restore sign, and check for directed +// rounding modes. L_SCR1 contains the rmode in the lower byte. +// +un_rnge: + btstb #1,L_SCR1+3(%a6) //check for rn and rz + beqs un_rnrz + tstb LOCAL_SGN(%a0) //check for sign + bnes un_rmrp_neg +// +// Sign is +. If rp, load +1.0, if rm, load +0.0 +// + cmpib #3,L_SCR1+3(%a6) //check for rp + beqs un_ldpone //if rp, load +1.0 + bsr ld_pzero //if rm, load +0.0 + bra t_inx2 +un_ldpone: + bsr ld_pone + bra t_inx2 +// +// Sign is -. If rm, load -1.0, if rp, load -0.0 +// +un_rmrp_neg: + cmpib #2,L_SCR1+3(%a6) //check for rm + beqs un_ldmone //if rm, load -1.0 + bsr ld_mzero //if rp, load -0.0 + bra t_inx2 +un_ldmone: + bsr ld_mone + bra t_inx2 +// +// Rmode is rn or rz; return signed zero +// +un_rnrz: + tstb LOCAL_SGN(%a0) //check for sign + bnes un_rnrz_neg + bsr ld_pzero + bra t_inx2 +un_rnrz_neg: + bsr ld_mzero + bra t_inx2 + +// +// Input is greater than 2^63. All bits are significant. Return +// the input. +// +out_rnge: + bfclr LOCAL_SGN(%a0){#0:#8} //change back to IEEE ext format + beqs intps + bsetb #sign_bit,LOCAL_EX(%a0) +intps: + fmovel %fpcr,-(%sp) + fmovel #0,%fpcr + fmovex LOCAL_EX(%a0),%fp0 //if exp > 63 +// ;then return X to the user +// ;there are no fraction bits + fmovel (%sp)+,%fpcr + rts + +in_rnge: +// ;shift off fraction bits + clrl %d0 //clear d0 - initial g,r,s for +// ;dnrm_lp + movel #0x403e,%d1 //set threshold for dnrm_lp +// ;assumes a0 points to operand + bsr dnrm_lp +// ;returns unnormalized number +// ;pointed by a0 +// ;output d0 supplies g,r,s +// ;used by round + movel L_SCR1(%a6),%d1 //use selected rounding mode +// +// + bsr round //round the unnorm based on users +// ;input a0 ptr to ext X +// ; d0 g,r,s bits +// ; d1 PREC/MODE info +// ;output a0 ptr to rounded result +// ;inexact flag set in USER_FPSR +// ;if initial grs set +// +// normalize the rounded result and store value in fp0 +// + bsr nrm_set //normalize the unnorm +// ;Input: a0 points to operand to +// ;be normalized +// ;Output: a0 points to normalized +// ;result + bfclr LOCAL_SGN(%a0){#0:#8} + beqs nrmrndp + bsetb #sign_bit,LOCAL_EX(%a0) //return to IEEE extended format +nrmrndp: + fmovel %fpcr,-(%sp) + fmovel #0,%fpcr + fmovex LOCAL_EX(%a0),%fp0 //move result to fp0 + fmovel (%sp)+,%fpcr + rts + + |end |