sint.S (5696B)
1| 2| sint.sa 3.1 12/10/90 3| 4| The entry point sINT computes the rounded integer 5| equivalent of the input argument, sINTRZ computes 6| the integer rounded to zero of the input argument. 7| 8| Entry points sint and sintrz are called from do_func 9| to emulate the fint and fintrz unimplemented instructions, 10| respectively. Entry point sintdo is used by bindec. 11| 12| Input: (Entry points sint and sintrz) Double-extended 13| number X in the ETEMP space in the floating-point 14| save stack. 15| (Entry point sintdo) Double-extended number X in 16| location pointed to by the address register a0. 17| (Entry point sintd) Double-extended denormalized 18| number X in the ETEMP space in the floating-point 19| save stack. 20| 21| Output: The function returns int(X) or intrz(X) in fp0. 22| 23| Modifies: fp0. 24| 25| Algorithm: (sint and sintrz) 26| 27| 1. If exp(X) >= 63, return X. 28| If exp(X) < 0, return +/- 0 or +/- 1, according to 29| the rounding mode. 30| 31| 2. (X is in range) set rsc = 63 - exp(X). Unnormalize the 32| result to the exponent $403e. 33| 34| 3. Round the result in the mode given in USER_FPCR. For 35| sintrz, force round-to-zero mode. 36| 37| 4. Normalize the rounded result; store in fp0. 38| 39| For the denormalized cases, force the correct result 40| for the given sign and rounding mode. 41| 42| Sign(X) 43| RMODE + - 44| ----- -------- 45| RN +0 -0 46| RZ +0 -0 47| RM +0 -1 48| RP +1 -0 49| 50| 51| Copyright (C) Motorola, Inc. 1990 52| All Rights Reserved 53| 54| For details on the license for this file, please see the 55| file, README, in this same directory. 56 57|SINT idnt 2,1 | Motorola 040 Floating Point Software Package 58 59 |section 8 60 61#include "fpsp.h" 62 63 |xref dnrm_lp 64 |xref nrm_set 65 |xref round 66 |xref t_inx2 67 |xref ld_pone 68 |xref ld_mone 69 |xref ld_pzero 70 |xref ld_mzero 71 |xref snzrinx 72 73| 74| FINT 75| 76 .global sint 77sint: 78 bfextu FPCR_MODE(%a6){#2:#2},%d1 |use user's mode for rounding 79| ;implicitly has extend precision 80| ;in upper word. 81 movel %d1,L_SCR1(%a6) |save mode bits 82 bras sintexc 83 84| 85| FINT with extended denorm inputs. 86| 87 .global sintd 88sintd: 89 btstb #5,FPCR_MODE(%a6) 90 beq snzrinx |if round nearest or round zero, +/- 0 91 btstb #4,FPCR_MODE(%a6) 92 beqs rnd_mns 93rnd_pls: 94 btstb #sign_bit,LOCAL_EX(%a0) 95 bnes sintmz 96 bsr ld_pone |if round plus inf and pos, answer is +1 97 bra t_inx2 98rnd_mns: 99 btstb #sign_bit,LOCAL_EX(%a0) 100 beqs sintpz 101 bsr ld_mone |if round mns inf and neg, answer is -1 102 bra t_inx2 103sintpz: 104 bsr ld_pzero 105 bra t_inx2 106sintmz: 107 bsr ld_mzero 108 bra t_inx2 109 110| 111| FINTRZ 112| 113 .global sintrz 114sintrz: 115 movel #1,L_SCR1(%a6) |use rz mode for rounding 116| ;implicitly has extend precision 117| ;in upper word. 118 bras sintexc 119| 120| SINTDO 121| 122| Input: a0 points to an IEEE extended format operand 123| Output: fp0 has the result 124| 125| Exceptions: 126| 127| If the subroutine results in an inexact operation, the inx2 and 128| ainx bits in the USER_FPSR are set. 129| 130| 131 .global sintdo 132sintdo: 133 bfextu FPCR_MODE(%a6){#2:#2},%d1 |use user's mode for rounding 134| ;implicitly has ext precision 135| ;in upper word. 136 movel %d1,L_SCR1(%a6) |save mode bits 137| 138| Real work of sint is in sintexc 139| 140sintexc: 141 bclrb #sign_bit,LOCAL_EX(%a0) |convert to internal extended 142| ;format 143 sne LOCAL_SGN(%a0) 144 cmpw #0x403e,LOCAL_EX(%a0) |check if (unbiased) exp > 63 145 bgts out_rnge |branch if exp < 63 146 cmpw #0x3ffd,LOCAL_EX(%a0) |check if (unbiased) exp < 0 147 bgt in_rnge |if 63 >= exp > 0, do calc 148| 149| Input is less than zero. Restore sign, and check for directed 150| rounding modes. L_SCR1 contains the rmode in the lower byte. 151| 152un_rnge: 153 btstb #1,L_SCR1+3(%a6) |check for rn and rz 154 beqs un_rnrz 155 tstb LOCAL_SGN(%a0) |check for sign 156 bnes un_rmrp_neg 157| 158| Sign is +. If rp, load +1.0, if rm, load +0.0 159| 160 cmpib #3,L_SCR1+3(%a6) |check for rp 161 beqs un_ldpone |if rp, load +1.0 162 bsr ld_pzero |if rm, load +0.0 163 bra t_inx2 164un_ldpone: 165 bsr ld_pone 166 bra t_inx2 167| 168| Sign is -. If rm, load -1.0, if rp, load -0.0 169| 170un_rmrp_neg: 171 cmpib #2,L_SCR1+3(%a6) |check for rm 172 beqs un_ldmone |if rm, load -1.0 173 bsr ld_mzero |if rp, load -0.0 174 bra t_inx2 175un_ldmone: 176 bsr ld_mone 177 bra t_inx2 178| 179| Rmode is rn or rz; return signed zero 180| 181un_rnrz: 182 tstb LOCAL_SGN(%a0) |check for sign 183 bnes un_rnrz_neg 184 bsr ld_pzero 185 bra t_inx2 186un_rnrz_neg: 187 bsr ld_mzero 188 bra t_inx2 189 190| 191| Input is greater than 2^63. All bits are significant. Return 192| the input. 193| 194out_rnge: 195 bfclr LOCAL_SGN(%a0){#0:#8} |change back to IEEE ext format 196 beqs intps 197 bsetb #sign_bit,LOCAL_EX(%a0) 198intps: 199 fmovel %fpcr,-(%sp) 200 fmovel #0,%fpcr 201 fmovex LOCAL_EX(%a0),%fp0 |if exp > 63 202| ;then return X to the user 203| ;there are no fraction bits 204 fmovel (%sp)+,%fpcr 205 rts 206 207in_rnge: 208| ;shift off fraction bits 209 clrl %d0 |clear d0 - initial g,r,s for 210| ;dnrm_lp 211 movel #0x403e,%d1 |set threshold for dnrm_lp 212| ;assumes a0 points to operand 213 bsr dnrm_lp 214| ;returns unnormalized number 215| ;pointed by a0 216| ;output d0 supplies g,r,s 217| ;used by round 218 movel L_SCR1(%a6),%d1 |use selected rounding mode 219| 220| 221 bsr round |round the unnorm based on users 222| ;input a0 ptr to ext X 223| ; d0 g,r,s bits 224| ; d1 PREC/MODE info 225| ;output a0 ptr to rounded result 226| ;inexact flag set in USER_FPSR 227| ;if initial grs set 228| 229| normalize the rounded result and store value in fp0 230| 231 bsr nrm_set |normalize the unnorm 232| ;Input: a0 points to operand to 233| ;be normalized 234| ;Output: a0 points to normalized 235| ;result 236 bfclr LOCAL_SGN(%a0){#0:#8} 237 beqs nrmrndp 238 bsetb #sign_bit,LOCAL_EX(%a0) |return to IEEE extended format 239nrmrndp: 240 fmovel %fpcr,-(%sp) 241 fmovel #0,%fpcr 242 fmovex LOCAL_EX(%a0),%fp0 |move result to fp0 243 fmovel (%sp)+,%fpcr 244 rts 245 246 |end