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255 lines
6.8 KiB
255 lines
6.8 KiB
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| x_store.sa 3.2 1/24/91 |
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| store --- store operand to memory or register |
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| Used by underflow and overflow handlers. |
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| a6 = points to fp value to be stored. |
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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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X_STORE: |idnt 2,1 | Motorola 040 Floating Point Software Package |
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|section 8 |
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fpreg_mask: |
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.byte 0x80,0x40,0x20,0x10,0x08,0x04,0x02,0x01 |
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#include "fpsp.h" |
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|xref mem_write |
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|xref get_fline |
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|xref g_opcls |
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|xref g_dfmtou |
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|xref reg_dest |
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.global dest_ext |
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.global dest_dbl |
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.global dest_sgl |
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.global store |
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store: |
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btstb #E3,E_BYTE(%a6) |
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beqs E1_sto |
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E3_sto: |
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movel CMDREG3B(%a6),%d0 |
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bfextu %d0{#6:#3},%d0 |isolate dest. reg from cmdreg3b |
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sto_fp: |
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lea fpreg_mask,%a1 |
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moveb (%a1,%d0.w),%d0 |convert reg# to dynamic register mask |
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tstb LOCAL_SGN(%a0) |
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beqs is_pos |
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bsetb #sign_bit,LOCAL_EX(%a0) |
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is_pos: |
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fmovemx (%a0),%d0 |move to correct register |
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| if fp0-fp3 is being modified, we must put a copy |
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| in the USER_FPn variable on the stack because all exception |
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| handlers restore fp0-fp3 from there. |
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| |
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cmpb #0x80,%d0 |
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bnes not_fp0 |
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fmovemx %fp0-%fp0,USER_FP0(%a6) |
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rts |
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not_fp0: |
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cmpb #0x40,%d0 |
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bnes not_fp1 |
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fmovemx %fp1-%fp1,USER_FP1(%a6) |
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rts |
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not_fp1: |
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cmpb #0x20,%d0 |
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bnes not_fp2 |
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fmovemx %fp2-%fp2,USER_FP2(%a6) |
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rts |
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not_fp2: |
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cmpb #0x10,%d0 |
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bnes not_fp3 |
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fmovemx %fp3-%fp3,USER_FP3(%a6) |
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rts |
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not_fp3: |
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rts |
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E1_sto: |
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bsrl g_opcls |returns opclass in d0 |
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cmpib #3,%d0 |
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beq opc011 |branch if opclass 3 |
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movel CMDREG1B(%a6),%d0 |
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bfextu %d0{#6:#3},%d0 |extract destination register |
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bras sto_fp |
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opc011: |
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bsrl g_dfmtou |returns dest format in d0 |
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| ;ext=00, sgl=01, dbl=10 |
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movel %a0,%a1 |save source addr in a1 |
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movel EXC_EA(%a6),%a0 |get the address |
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cmpil #0,%d0 |if dest format is extended |
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beq dest_ext |then branch |
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cmpil #1,%d0 |if dest format is single |
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beq dest_sgl |then branch |
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| fall through to dest_dbl |
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| dest_dbl --- write double precision value to user space |
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|Input |
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| a0 -> destination address |
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| a1 -> source in extended precision |
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|Output |
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| a0 -> destroyed |
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| a1 -> destroyed |
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| d0 -> 0 |
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|Changes extended precision to double precision. |
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| Note: no attempt is made to round the extended value to double. |
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| dbl_sign = ext_sign |
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| dbl_exp = ext_exp - $3fff(ext bias) + $7ff(dbl bias) |
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| get rid of ext integer bit |
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| dbl_mant = ext_mant{62:12} |
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| --------------- --------------- --------------- |
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| extended -> |s| exp | |1| ms mant | | ls mant | |
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| --------------- --------------- --------------- |
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| 95 64 63 62 32 31 11 0 |
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| | | |
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| | | |
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| v v |
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| --------------- --------------- |
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| double -> |s|exp| mant | | mant | |
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| --------------- --------------- |
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| 63 51 32 31 0 |
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dest_dbl: |
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clrl %d0 |clear d0 |
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movew LOCAL_EX(%a1),%d0 |get exponent |
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subw #0x3fff,%d0 |subtract extended precision bias |
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cmpw #0x4000,%d0 |check if inf |
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beqs inf |if so, special case |
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addw #0x3ff,%d0 |add double precision bias |
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swap %d0 |d0 now in upper word |
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lsll #4,%d0 |d0 now in proper place for dbl prec exp |
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tstb LOCAL_SGN(%a1) |
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beqs get_mant |if positive, go process mantissa |
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bsetl #31,%d0 |if negative, put in sign information |
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| ; before continuing |
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bras get_mant |go process mantissa |
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inf: |
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movel #0x7ff00000,%d0 |load dbl inf exponent |
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clrl LOCAL_HI(%a1) |clear msb |
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tstb LOCAL_SGN(%a1) |
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beqs dbl_inf |if positive, go ahead and write it |
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bsetl #31,%d0 |if negative put in sign information |
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dbl_inf: |
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movel %d0,LOCAL_EX(%a1) |put the new exp back on the stack |
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bras dbl_wrt |
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get_mant: |
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movel LOCAL_HI(%a1),%d1 |get ms mantissa |
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bfextu %d1{#1:#20},%d1 |get upper 20 bits of ms |
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orl %d1,%d0 |put these bits in ms word of double |
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movel %d0,LOCAL_EX(%a1) |put the new exp back on the stack |
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movel LOCAL_HI(%a1),%d1 |get ms mantissa |
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movel #21,%d0 |load shift count |
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lsll %d0,%d1 |put lower 11 bits in upper bits |
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movel %d1,LOCAL_HI(%a1) |build lower lword in memory |
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movel LOCAL_LO(%a1),%d1 |get ls mantissa |
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bfextu %d1{#0:#21},%d0 |get ls 21 bits of double |
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orl %d0,LOCAL_HI(%a1) |put them in double result |
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dbl_wrt: |
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movel #0x8,%d0 |byte count for double precision number |
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exg %a0,%a1 |a0=supervisor source, a1=user dest |
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bsrl mem_write |move the number to the user's memory |
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rts |
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| dest_sgl --- write single precision value to user space |
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|Input |
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| a0 -> destination address |
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| a1 -> source in extended precision |
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|Output |
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| a0 -> destroyed |
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| a1 -> destroyed |
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| d0 -> 0 |
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|Changes extended precision to single precision. |
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| sgl_sign = ext_sign |
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| sgl_exp = ext_exp - $3fff(ext bias) + $7f(sgl bias) |
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| get rid of ext integer bit |
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| sgl_mant = ext_mant{62:12} |
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| --------------- --------------- --------------- |
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| extended -> |s| exp | |1| ms mant | | ls mant | |
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| --------------- --------------- --------------- |
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| 95 64 63 62 40 32 31 12 0 |
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| v v |
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| --------------- |
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| single -> |s|exp| mant | |
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| --------------- |
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| 31 22 0 |
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dest_sgl: |
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clrl %d0 |
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movew LOCAL_EX(%a1),%d0 |get exponent |
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subw #0x3fff,%d0 |subtract extended precision bias |
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cmpw #0x4000,%d0 |check if inf |
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beqs sinf |if so, special case |
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addw #0x7f,%d0 |add single precision bias |
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swap %d0 |put exp in upper word of d0 |
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lsll #7,%d0 |shift it into single exp bits |
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tstb LOCAL_SGN(%a1) |
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beqs get_sman |if positive, continue |
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bsetl #31,%d0 |if negative, put in sign first |
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bras get_sman |get mantissa |
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sinf: |
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movel #0x7f800000,%d0 |load single inf exp to d0 |
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tstb LOCAL_SGN(%a1) |
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beqs sgl_wrt |if positive, continue |
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bsetl #31,%d0 |if negative, put in sign info |
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bras sgl_wrt |
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get_sman: |
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movel LOCAL_HI(%a1),%d1 |get ms mantissa |
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bfextu %d1{#1:#23},%d1 |get upper 23 bits of ms |
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orl %d1,%d0 |put these bits in ms word of single |
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sgl_wrt: |
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movel %d0,L_SCR1(%a6) |put the new exp back on the stack |
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movel #0x4,%d0 |byte count for single precision number |
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tstl %a0 |users destination address |
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beqs sgl_Dn |destination is a data register |
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exg %a0,%a1 |a0=supervisor source, a1=user dest |
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leal L_SCR1(%a6),%a0 |point a0 to data |
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bsrl mem_write |move the number to the user's memory |
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rts |
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sgl_Dn: |
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bsrl get_fline |returns fline word in d0 |
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andw #0x7,%d0 |isolate register number |
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movel %d0,%d1 |d1 has size:reg formatted for reg_dest |
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orl #0x10,%d1 |reg_dest wants size added to reg# |
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bral reg_dest |size is X, rts in reg_dest will |
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| ;return to caller of dest_sgl |
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dest_ext: |
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tstb LOCAL_SGN(%a1) |put back sign into exponent word |
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beqs dstx_cont |
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bsetb #sign_bit,LOCAL_EX(%a1) |
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dstx_cont: |
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clrb LOCAL_SGN(%a1) |clear out the sign byte |
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movel #0x0c,%d0 |byte count for extended number |
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exg %a0,%a1 |a0=supervisor source, a1=user dest |
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bsrl mem_write |move the number to the user's memory |
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rts |
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|end
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