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