| | |
| | scale.sa 3.3 7/30/91 |
| | |
| | The entry point sSCALE computes the destination operand |
| | scaled by the source operand. If the absolute value of |
| | the source operand is (>= 2^14) an overflow or underflow |
| | is returned. |
| | |
| | The entry point sscale is called from do_func to emulate |
| | the fscale unimplemented instruction. |
| | |
| | Input: Double-extended destination operand in FPTEMP, |
| | double-extended source operand in ETEMP. |
| | |
| | Output: The function returns scale(X,Y) to fp0. |
| | |
| | Modifies: fp0. |
| | |
| | Algorithm: |
| | |
| | Copyright (C) Motorola, Inc. 1990 |
| | All Rights Reserved |
| | |
| | For details on the license for this file, please see the |
| | file, README, in this same directory. |
| |
| |SCALE idnt 2,1 | Motorola 040 Floating Point Software Package |
| |
| |section 8 |
| |
| #include "fpsp.h" |
| |
| |xref t_ovfl2 |
| |xref t_unfl |
| |xref round |
| |xref t_resdnrm |
| |
| SRC_BNDS: .short 0x3fff,0x400c |
| |
| | |
| | This entry point is used by the unimplemented instruction exception |
| | handler. |
| | |
| | |
| | |
| | FSCALE |
| | |
| .global sscale |
| sscale: |
| fmovel #0,%fpcr |clr user enabled exc |
| clrl %d1 |
| movew FPTEMP(%a6),%d1 |get dest exponent |
| smi L_SCR1(%a6) |use L_SCR1 to hold sign |
| andil #0x7fff,%d1 |strip sign |
| movew ETEMP(%a6),%d0 |check src bounds |
| andiw #0x7fff,%d0 |clr sign bit |
| cmp2w SRC_BNDS,%d0 |
| bccs src_in |
| cmpiw #0x400c,%d0 |test for too large |
| bge src_out |
| | |
| | The source input is below 1, so we check for denormalized numbers |
| | and set unfl. |
| | |
| src_small: |
| moveb DTAG(%a6),%d0 |
| andib #0xe0,%d0 |
| tstb %d0 |
| beqs no_denorm |
| st STORE_FLG(%a6) |dest already contains result |
| orl #unfl_mask,USER_FPSR(%a6) |set UNFL |
| den_done: |
| leal FPTEMP(%a6),%a0 |
| bra t_resdnrm |
| no_denorm: |
| fmovel USER_FPCR(%a6),%FPCR |
| fmovex FPTEMP(%a6),%fp0 |simply return dest |
| rts |
| |
| |
| | |
| | Source is within 2^14 range. To perform the int operation, |
| | move it to d0. |
| | |
| src_in: |
| fmovex ETEMP(%a6),%fp0 |move in src for int |
| fmovel #rz_mode,%fpcr |force rz for src conversion |
| fmovel %fp0,%d0 |int src to d0 |
| fmovel #0,%FPSR |clr status from above |
| tstw ETEMP(%a6) |check src sign |
| blt src_neg |
| | |
| | Source is positive. Add the src to the dest exponent. |
| | The result can be denormalized, if src = 0, or overflow, |
| | if the result of the add sets a bit in the upper word. |
| | |
| src_pos: |
| tstw %d1 |check for denorm |
| beq dst_dnrm |
| addl %d0,%d1 |add src to dest exp |
| beqs denorm |if zero, result is denorm |
| cmpil #0x7fff,%d1 |test for overflow |
| bges ovfl |
| tstb L_SCR1(%a6) |
| beqs spos_pos |
| orw #0x8000,%d1 |
| spos_pos: |
| movew %d1,FPTEMP(%a6) |result in FPTEMP |
| fmovel USER_FPCR(%a6),%FPCR |
| fmovex FPTEMP(%a6),%fp0 |write result to fp0 |
| rts |
| ovfl: |
| tstb L_SCR1(%a6) |
| beqs sovl_pos |
| orw #0x8000,%d1 |
| sovl_pos: |
| movew FPTEMP(%a6),ETEMP(%a6) |result in ETEMP |
| movel FPTEMP_HI(%a6),ETEMP_HI(%a6) |
| movel FPTEMP_LO(%a6),ETEMP_LO(%a6) |
| bra t_ovfl2 |
| |
| denorm: |
| tstb L_SCR1(%a6) |
| beqs den_pos |
| orw #0x8000,%d1 |
| den_pos: |
| tstl FPTEMP_HI(%a6) |check j bit |
| blts nden_exit |if set, not denorm |
| movew %d1,ETEMP(%a6) |input expected in ETEMP |
| movel FPTEMP_HI(%a6),ETEMP_HI(%a6) |
| movel FPTEMP_LO(%a6),ETEMP_LO(%a6) |
| orl #unfl_bit,USER_FPSR(%a6) |set unfl |
| leal ETEMP(%a6),%a0 |
| bra t_resdnrm |
| nden_exit: |
| movew %d1,FPTEMP(%a6) |result in FPTEMP |
| fmovel USER_FPCR(%a6),%FPCR |
| fmovex FPTEMP(%a6),%fp0 |write result to fp0 |
| rts |
| |
| | |
| | Source is negative. Add the src to the dest exponent. |
| | (The result exponent will be reduced). The result can be |
| | denormalized. |
| | |
| src_neg: |
| addl %d0,%d1 |add src to dest |
| beqs denorm |if zero, result is denorm |
| blts fix_dnrm |if negative, result is |
| | ;needing denormalization |
| tstb L_SCR1(%a6) |
| beqs sneg_pos |
| orw #0x8000,%d1 |
| sneg_pos: |
| movew %d1,FPTEMP(%a6) |result in FPTEMP |
| fmovel USER_FPCR(%a6),%FPCR |
| fmovex FPTEMP(%a6),%fp0 |write result to fp0 |
| rts |
| |
| |
| | |
| | The result exponent is below denorm value. Test for catastrophic |
| | underflow and force zero if true. If not, try to shift the |
| | mantissa right until a zero exponent exists. |
| | |
| fix_dnrm: |
| cmpiw #0xffc0,%d1 |lower bound for normalization |
| blt fix_unfl |if lower, catastrophic unfl |
| movew %d1,%d0 |use d0 for exp |
| movel %d2,-(%a7) |free d2 for norm |
| movel FPTEMP_HI(%a6),%d1 |
| movel FPTEMP_LO(%a6),%d2 |
| clrl L_SCR2(%a6) |
| fix_loop: |
| addw #1,%d0 |drive d0 to 0 |
| lsrl #1,%d1 |while shifting the |
| roxrl #1,%d2 |mantissa to the right |
| bccs no_carry |
| st L_SCR2(%a6) |use L_SCR2 to capture inex |
| no_carry: |
| tstw %d0 |it is finished when |
| blts fix_loop |d0 is zero or the mantissa |
| tstb L_SCR2(%a6) |
| beqs tst_zero |
| orl #unfl_inx_mask,USER_FPSR(%a6) |
| | ;set unfl, aunfl, ainex |
| | |
| | Test for zero. If zero, simply use fmove to return +/- zero |
| | to the fpu. |
| | |
| tst_zero: |
| clrw FPTEMP_EX(%a6) |
| tstb L_SCR1(%a6) |test for sign |
| beqs tst_con |
| orw #0x8000,FPTEMP_EX(%a6) |set sign bit |
| tst_con: |
| movel %d1,FPTEMP_HI(%a6) |
| movel %d2,FPTEMP_LO(%a6) |
| movel (%a7)+,%d2 |
| tstl %d1 |
| bnes not_zero |
| tstl FPTEMP_LO(%a6) |
| bnes not_zero |
| | |
| | Result is zero. Check for rounding mode to set lsb. If the |
| | mode is rp, and the zero is positive, return smallest denorm. |
| | If the mode is rm, and the zero is negative, return smallest |
| | negative denorm. |
| | |
| btstb #5,FPCR_MODE(%a6) |test if rm or rp |
| beqs no_dir |
| btstb #4,FPCR_MODE(%a6) |check which one |
| beqs zer_rm |
| zer_rp: |
| tstb L_SCR1(%a6) |check sign |
| bnes no_dir |if set, neg op, no inc |
| movel #1,FPTEMP_LO(%a6) |set lsb |
| bras sm_dnrm |
| zer_rm: |
| tstb L_SCR1(%a6) |check sign |
| beqs no_dir |if clr, neg op, no inc |
| movel #1,FPTEMP_LO(%a6) |set lsb |
| orl #neg_mask,USER_FPSR(%a6) |set N |
| bras sm_dnrm |
| no_dir: |
| fmovel USER_FPCR(%a6),%FPCR |
| fmovex FPTEMP(%a6),%fp0 |use fmove to set cc's |
| rts |
| |
| | |
| | The rounding mode changed the zero to a smallest denorm. Call |
| | t_resdnrm with exceptional operand in ETEMP. |
| | |
| sm_dnrm: |
| movel FPTEMP_EX(%a6),ETEMP_EX(%a6) |
| movel FPTEMP_HI(%a6),ETEMP_HI(%a6) |
| movel FPTEMP_LO(%a6),ETEMP_LO(%a6) |
| leal ETEMP(%a6),%a0 |
| bra t_resdnrm |
| |
| | |
| | Result is still denormalized. |
| | |
| not_zero: |
| orl #unfl_mask,USER_FPSR(%a6) |set unfl |
| tstb L_SCR1(%a6) |check for sign |
| beqs fix_exit |
| orl #neg_mask,USER_FPSR(%a6) |set N |
| fix_exit: |
| bras sm_dnrm |
| |
| |
| | |
| | The result has underflowed to zero. Return zero and set |
| | unfl, aunfl, and ainex. |
| | |
| fix_unfl: |
| orl #unfl_inx_mask,USER_FPSR(%a6) |
| btstb #5,FPCR_MODE(%a6) |test if rm or rp |
| beqs no_dir2 |
| btstb #4,FPCR_MODE(%a6) |check which one |
| beqs zer_rm2 |
| zer_rp2: |
| tstb L_SCR1(%a6) |check sign |
| bnes no_dir2 |if set, neg op, no inc |
| clrl FPTEMP_EX(%a6) |
| clrl FPTEMP_HI(%a6) |
| movel #1,FPTEMP_LO(%a6) |set lsb |
| bras sm_dnrm |return smallest denorm |
| zer_rm2: |
| tstb L_SCR1(%a6) |check sign |
| beqs no_dir2 |if clr, neg op, no inc |
| movew #0x8000,FPTEMP_EX(%a6) |
| clrl FPTEMP_HI(%a6) |
| movel #1,FPTEMP_LO(%a6) |set lsb |
| orl #neg_mask,USER_FPSR(%a6) |set N |
| bra sm_dnrm |return smallest denorm |
| |
| no_dir2: |
| tstb L_SCR1(%a6) |
| bges pos_zero |
| neg_zero: |
| clrl FP_SCR1(%a6) |clear the exceptional operand |
| clrl FP_SCR1+4(%a6) |for gen_except. |
| clrl FP_SCR1+8(%a6) |
| fmoves #0x80000000,%fp0 |
| rts |
| pos_zero: |
| clrl FP_SCR1(%a6) |clear the exceptional operand |
| clrl FP_SCR1+4(%a6) |for gen_except. |
| clrl FP_SCR1+8(%a6) |
| fmoves #0x00000000,%fp0 |
| rts |
| |
| | |
| | The destination is a denormalized number. It must be handled |
| | by first shifting the bits in the mantissa until it is normalized, |
| | then adding the remainder of the source to the exponent. |
| | |
| dst_dnrm: |
| moveml %d2/%d3,-(%a7) |
| movew FPTEMP_EX(%a6),%d1 |
| movel FPTEMP_HI(%a6),%d2 |
| movel FPTEMP_LO(%a6),%d3 |
| dst_loop: |
| tstl %d2 |test for normalized result |
| blts dst_norm |exit loop if so |
| tstl %d0 |otherwise, test shift count |
| beqs dst_fin |if zero, shifting is done |
| subil #1,%d0 |dec src |
| lsll #1,%d3 |
| roxll #1,%d2 |
| bras dst_loop |
| | |
| | Destination became normalized. Simply add the remaining |
| | portion of the src to the exponent. |
| | |
| dst_norm: |
| addw %d0,%d1 |dst is normalized; add src |
| tstb L_SCR1(%a6) |
| beqs dnrm_pos |
| orl #0x8000,%d1 |
| dnrm_pos: |
| movemw %d1,FPTEMP_EX(%a6) |
| moveml %d2,FPTEMP_HI(%a6) |
| moveml %d3,FPTEMP_LO(%a6) |
| fmovel USER_FPCR(%a6),%FPCR |
| fmovex FPTEMP(%a6),%fp0 |
| moveml (%a7)+,%d2/%d3 |
| rts |
| |
| | |
| | Destination remained denormalized. Call t_excdnrm with |
| | exceptional operand in ETEMP. |
| | |
| dst_fin: |
| tstb L_SCR1(%a6) |check for sign |
| beqs dst_exit |
| orl #neg_mask,USER_FPSR(%a6) |set N |
| orl #0x8000,%d1 |
| dst_exit: |
| movemw %d1,ETEMP_EX(%a6) |
| moveml %d2,ETEMP_HI(%a6) |
| moveml %d3,ETEMP_LO(%a6) |
| orl #unfl_mask,USER_FPSR(%a6) |set unfl |
| moveml (%a7)+,%d2/%d3 |
| leal ETEMP(%a6),%a0 |
| bra t_resdnrm |
| |
| | |
| | Source is outside of 2^14 range. Test the sign and branch |
| | to the appropriate exception handler. |
| | |
| src_out: |
| tstb L_SCR1(%a6) |
| beqs scro_pos |
| orl #0x8000,%d1 |
| scro_pos: |
| movel FPTEMP_HI(%a6),ETEMP_HI(%a6) |
| movel FPTEMP_LO(%a6),ETEMP_LO(%a6) |
| tstw ETEMP(%a6) |
| blts res_neg |
| res_pos: |
| movew %d1,ETEMP(%a6) |result in ETEMP |
| bra t_ovfl2 |
| res_neg: |
| movew %d1,ETEMP(%a6) |result in ETEMP |
| leal ETEMP(%a6),%a0 |
| bra t_unfl |
| |end |
