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Diffstat (limited to 'c/src/lib/libcpu/m68k/m68040/fpsp/round.S')
| -rw-r--r-- | c/src/lib/libcpu/m68k/m68040/fpsp/round.S | 651 |
1 files changed, 0 insertions, 651 deletions
diff --git a/c/src/lib/libcpu/m68k/m68040/fpsp/round.S b/c/src/lib/libcpu/m68k/m68040/fpsp/round.S deleted file mode 100644 index b9b5be1cc5..0000000000 --- a/c/src/lib/libcpu/m68k/m68040/fpsp/round.S +++ /dev/null @@ -1,651 +0,0 @@ -#include "fpsp-namespace.h" -// -// -// round.sa 3.4 7/29/91 -// -// handle rounding and normalization tasks -// -// -// -// Copyright (C) Motorola, Inc. 1990 -// All Rights Reserved -// -// THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA -// The copyright notice above does not evidence any -// actual or intended publication of such source code. - -//ROUND idnt 2,1 | Motorola 040 Floating Point Software Package - - |section 8 - -#include "fpsp.defs" - -// -// round --- round result according to precision/mode -// -// a0 points to the input operand in the internal extended format -// d1(high word) contains rounding precision: -// ext = $0000xxxx -// sgl = $0001xxxx -// dbl = $0002xxxx -// d1(low word) contains rounding mode: -// RN = $xxxx0000 -// RZ = $xxxx0001 -// RM = $xxxx0010 -// RP = $xxxx0011 -// d0{31:29} contains the g,r,s bits (extended) -// -// On return the value pointed to by a0 is correctly rounded, -// a0 is preserved and the g-r-s bits in d0 are cleared. -// The result is not typed - the tag field is invalid. The -// result is still in the internal extended format. -// -// The INEX bit of USER_FPSR will be set if the rounded result was -// inexact (i.e. if any of the g-r-s bits were set). -// - - .global round -round: -// If g=r=s=0 then result is exact and round is done, else set -// the inex flag in status reg and continue. -// - bsrs ext_grs //this subroutine looks at the -// :rounding precision and sets -// ;the appropriate g-r-s bits. - tstl %d0 //if grs are zero, go force - bne rnd_cont //lower bits to zero for size - - swap %d1 //set up d1.w for round prec. - bra truncate - -rnd_cont: -// -// Use rounding mode as an index into a jump table for these modes. -// - orl #inx2a_mask,USER_FPSR(%a6) //set inex2/ainex - lea mode_tab,%a1 - movel (%a1,%d1.w*4),%a1 - jmp (%a1) -// -// Jump table indexed by rounding mode in d1.w. All following assumes -// grs != 0. -// -mode_tab: - .long rnd_near - .long rnd_zero - .long rnd_mnus - .long rnd_plus -// -// ROUND PLUS INFINITY -// -// If sign of fp number = 0 (positive), then add 1 to l. -// -rnd_plus: - swap %d1 //set up d1 for round prec. - tstb LOCAL_SGN(%a0) //check for sign - bmi truncate //if positive then truncate - movel #0xffffffff,%d0 //force g,r,s to be all f's - lea add_to_l,%a1 - movel (%a1,%d1.w*4),%a1 - jmp (%a1) -// -// ROUND MINUS INFINITY -// -// If sign of fp number = 1 (negative), then add 1 to l. -// -rnd_mnus: - swap %d1 //set up d1 for round prec. - tstb LOCAL_SGN(%a0) //check for sign - bpl truncate //if negative then truncate - movel #0xffffffff,%d0 //force g,r,s to be all f's - lea add_to_l,%a1 - movel (%a1,%d1.w*4),%a1 - jmp (%a1) -// -// ROUND ZERO -// -// Always truncate. -rnd_zero: - swap %d1 //set up d1 for round prec. - bra truncate -// -// -// ROUND NEAREST -// -// If (g=1), then add 1 to l and if (r=s=0), then clear l -// Note that this will round to even in case of a tie. -// -rnd_near: - swap %d1 //set up d1 for round prec. - asll #1,%d0 //shift g-bit to c-bit - bcc truncate //if (g=1) then - lea add_to_l,%a1 - movel (%a1,%d1.w*4),%a1 - jmp (%a1) - -// -// ext_grs --- extract guard, round and sticky bits -// -// Input: d1 = PREC:ROUND -// Output: d0{31:29}= guard, round, sticky -// -// The ext_grs extract the guard/round/sticky bits according to the -// selected rounding precision. It is called by the round subroutine -// only. All registers except d0 are kept intact. d0 becomes an -// updated guard,round,sticky in d0{31:29} -// -// Notes: the ext_grs uses the round PREC, and therefore has to swap d1 -// prior to usage, and needs to restore d1 to original. -// -ext_grs: - swap %d1 //have d1.w point to round precision - cmpiw #0,%d1 - bnes sgl_or_dbl - bras end_ext_grs - -sgl_or_dbl: - moveml %d2/%d3,-(%a7) //make some temp registers - cmpiw #1,%d1 - bnes grs_dbl -grs_sgl: - bfextu LOCAL_HI(%a0){#24:#2},%d3 //sgl prec. g-r are 2 bits right - movel #30,%d2 //of the sgl prec. limits - lsll %d2,%d3 //shift g-r bits to MSB of d3 - movel LOCAL_HI(%a0),%d2 //get word 2 for s-bit test - andil #0x0000003f,%d2 //s bit is the or of all other - bnes st_stky //bits to the right of g-r - tstl LOCAL_LO(%a0) //test lower mantissa - bnes st_stky //if any are set, set sticky - tstl %d0 //test original g,r,s - bnes st_stky //if any are set, set sticky - bras end_sd //if words 3 and 4 are clr, exit -grs_dbl: - bfextu LOCAL_LO(%a0){#21:#2},%d3 //dbl-prec. g-r are 2 bits right - movel #30,%d2 //of the dbl prec. limits - lsll %d2,%d3 //shift g-r bits to the MSB of d3 - movel LOCAL_LO(%a0),%d2 //get lower mantissa for s-bit test - andil #0x000001ff,%d2 //s bit is the or-ing of all - bnes st_stky //other bits to the right of g-r - tstl %d0 //test word original g,r,s - bnes st_stky //if any are set, set sticky - bras end_sd //if clear, exit -st_stky: - bset #rnd_stky_bit,%d3 -end_sd: - movel %d3,%d0 //return grs to d0 - moveml (%a7)+,%d2/%d3 //restore scratch registers -end_ext_grs: - swap %d1 //restore d1 to original - rts - -//******************* Local Equates - .set ad_1_sgl,0x00000100 // constant to add 1 to l-bit in sgl prec - .set ad_1_dbl,0x00000800 // constant to add 1 to l-bit in dbl prec - - -//Jump table for adding 1 to the l-bit indexed by rnd prec - -add_to_l: - .long add_ext - .long add_sgl - .long add_dbl - .long add_dbl -// -// ADD SINGLE -// -add_sgl: - addl #ad_1_sgl,LOCAL_HI(%a0) - bccs scc_clr //no mantissa overflow - roxrw LOCAL_HI(%a0) //shift v-bit back in - roxrw LOCAL_HI+2(%a0) //shift v-bit back in - addw #0x1,LOCAL_EX(%a0) //and incr exponent -scc_clr: - tstl %d0 //test for rs = 0 - bnes sgl_done - andiw #0xfe00,LOCAL_HI+2(%a0) //clear the l-bit -sgl_done: - andil #0xffffff00,LOCAL_HI(%a0) //truncate bits beyond sgl limit - clrl LOCAL_LO(%a0) //clear d2 - rts - -// -// ADD EXTENDED -// -add_ext: - addql #1,LOCAL_LO(%a0) //add 1 to l-bit - bccs xcc_clr //test for carry out - addql #1,LOCAL_HI(%a0) //propagate carry - bccs xcc_clr - roxrw LOCAL_HI(%a0) //mant is 0 so restore v-bit - roxrw LOCAL_HI+2(%a0) //mant is 0 so restore v-bit - roxrw LOCAL_LO(%a0) - roxrw LOCAL_LO+2(%a0) - addw #0x1,LOCAL_EX(%a0) //and inc exp -xcc_clr: - tstl %d0 //test rs = 0 - bnes add_ext_done - andib #0xfe,LOCAL_LO+3(%a0) //clear the l bit -add_ext_done: - rts -// -// ADD DOUBLE -// -add_dbl: - addl #ad_1_dbl,LOCAL_LO(%a0) - bccs dcc_clr - addql #1,LOCAL_HI(%a0) //propagate carry - bccs dcc_clr - roxrw LOCAL_HI(%a0) //mant is 0 so restore v-bit - roxrw LOCAL_HI+2(%a0) //mant is 0 so restore v-bit - roxrw LOCAL_LO(%a0) - roxrw LOCAL_LO+2(%a0) - addw #0x1,LOCAL_EX(%a0) //incr exponent -dcc_clr: - tstl %d0 //test for rs = 0 - bnes dbl_done - andiw #0xf000,LOCAL_LO+2(%a0) //clear the l-bit - -dbl_done: - andil #0xfffff800,LOCAL_LO(%a0) //truncate bits beyond dbl limit - rts - -error: - rts -// -// Truncate all other bits -// -trunct: - .long end_rnd - .long sgl_done - .long dbl_done - .long dbl_done - -truncate: - lea trunct,%a1 - movel (%a1,%d1.w*4),%a1 - jmp (%a1) - -end_rnd: - rts - -// -// NORMALIZE -// -// These routines (nrm_zero & nrm_set) normalize the unnorm. This -// is done by shifting the mantissa left while decrementing the -// exponent. -// -// NRM_SET shifts and decrements until there is a 1 set in the integer -// bit of the mantissa (msb in d1). -// -// NRM_ZERO shifts and decrements until there is a 1 set in the integer -// bit of the mantissa (msb in d1) unless this would mean the exponent -// would go less than 0. In that case the number becomes a denorm - the -// exponent (d0) is set to 0 and the mantissa (d1 & d2) is not -// normalized. -// -// Note that both routines have been optimized (for the worst case) and -// therefore do not have the easy to follow decrement/shift loop. -// -// NRM_ZERO -// -// Distance to first 1 bit in mantissa = X -// Distance to 0 from exponent = Y -// If X < Y -// Then -// nrm_set -// Else -// shift mantissa by Y -// set exponent = 0 -// -//input: -// FP_SCR1 = exponent, ms mantissa part, ls mantissa part -//output: -// L_SCR1{4} = fpte15 or ete15 bit -// - .global nrm_zero -nrm_zero: - movew LOCAL_EX(%a0),%d0 - cmpw #64,%d0 //see if exp > 64 - bmis d0_less - bsr nrm_set //exp > 64 so exp won't exceed 0 - rts -d0_less: - moveml %d2/%d3/%d5/%d6,-(%a7) - movel LOCAL_HI(%a0),%d1 - movel LOCAL_LO(%a0),%d2 - - bfffo %d1{#0:#32},%d3 //get the distance to the first 1 -// ;in ms mant - beqs ms_clr //branch if no bits were set - cmpw %d3,%d0 //of X>Y - bmis greater //then exp will go past 0 (neg) if -// ;it is just shifted - bsr nrm_set //else exp won't go past 0 - moveml (%a7)+,%d2/%d3/%d5/%d6 - rts -greater: - movel %d2,%d6 //save ls mant in d6 - lsll %d0,%d2 //shift ls mant by count - lsll %d0,%d1 //shift ms mant by count - movel #32,%d5 - subl %d0,%d5 //make op a denorm by shifting bits - lsrl %d5,%d6 //by the number in the exp, then -// ;set exp = 0. - orl %d6,%d1 //shift the ls mant bits into the ms mant - movel #0,%d0 //same as if decremented exp to 0 -// ;while shifting - movew %d0,LOCAL_EX(%a0) - movel %d1,LOCAL_HI(%a0) - movel %d2,LOCAL_LO(%a0) - moveml (%a7)+,%d2/%d3/%d5/%d6 - rts -ms_clr: - bfffo %d2{#0:#32},%d3 //check if any bits set in ls mant - beqs all_clr //branch if none set - addw #32,%d3 - cmpw %d3,%d0 //if X>Y - bmis greater //then branch - bsr nrm_set //else exp won't go past 0 - moveml (%a7)+,%d2/%d3/%d5/%d6 - rts -all_clr: - movew #0,LOCAL_EX(%a0) //no mantissa bits set. Set exp = 0. - moveml (%a7)+,%d2/%d3/%d5/%d6 - rts -// -// NRM_SET -// - .global nrm_set -nrm_set: - movel %d7,-(%a7) - bfffo LOCAL_HI(%a0){#0:#32},%d7 //find first 1 in ms mant to d7) - beqs lower //branch if ms mant is all 0's - - movel %d6,-(%a7) - - subw %d7,LOCAL_EX(%a0) //sub exponent by count - movel LOCAL_HI(%a0),%d0 //d0 has ms mant - movel LOCAL_LO(%a0),%d1 //d1 has ls mant - - lsll %d7,%d0 //shift first 1 to j bit position - movel %d1,%d6 //copy ls mant into d6 - lsll %d7,%d6 //shift ls mant by count - movel %d6,LOCAL_LO(%a0) //store ls mant into memory - moveql #32,%d6 - subl %d7,%d6 //continue shift - lsrl %d6,%d1 //shift off all bits but those that will -// ;be shifted into ms mant - orl %d1,%d0 //shift the ls mant bits into the ms mant - movel %d0,LOCAL_HI(%a0) //store ms mant into memory - moveml (%a7)+,%d7/%d6 //restore registers - rts - -// -// We get here if ms mant was = 0, and we assume ls mant has bits -// set (otherwise this would have been tagged a zero not a denorm). -// -lower: - movew LOCAL_EX(%a0),%d0 //d0 has exponent - movel LOCAL_LO(%a0),%d1 //d1 has ls mant - subw #32,%d0 //account for ms mant being all zeros - bfffo %d1{#0:#32},%d7 //find first 1 in ls mant to d7) - subw %d7,%d0 //subtract shift count from exp - lsll %d7,%d1 //shift first 1 to integer bit in ms mant - movew %d0,LOCAL_EX(%a0) //store ms mant - movel %d1,LOCAL_HI(%a0) //store exp - clrl LOCAL_LO(%a0) //clear ls mant - movel (%a7)+,%d7 - rts -// -// denorm --- denormalize an intermediate result -// -// Used by underflow. -// -// Input: -// a0 points to the operand to be denormalized -// (in the internal extended format) -// -// d0: rounding precision -// Output: -// a0 points to the denormalized result -// (in the internal extended format) -// -// d0 is guard,round,sticky -// -// d0 comes into this routine with the rounding precision. It -// is then loaded with the denormalized exponent threshold for the -// rounding precision. -// - - .global denorm -denorm: - btstb #6,LOCAL_EX(%a0) //check for exponents between $7fff-$4000 - beqs no_sgn_ext - bsetb #7,LOCAL_EX(%a0) //sign extend if it is so -no_sgn_ext: - - cmpib #0,%d0 //if 0 then extended precision - bnes not_ext //else branch - - clrl %d1 //load d1 with ext threshold - clrl %d0 //clear the sticky flag - bsr dnrm_lp //denormalize the number - tstb %d1 //check for inex - beq no_inex //if clr, no inex - bras dnrm_inex //if set, set inex - -not_ext: - cmpil #1,%d0 //if 1 then single precision - beqs load_sgl //else must be 2, double prec - -load_dbl: - movew #dbl_thresh,%d1 //put copy of threshold in d1 - movel %d1,%d0 //copy d1 into d0 - subw LOCAL_EX(%a0),%d0 //diff = threshold - exp - cmpw #67,%d0 //if diff > 67 (mant + grs bits) - bpls chk_stky //then branch (all bits would be -// ; shifted off in denorm routine) - clrl %d0 //else clear the sticky flag - bsr dnrm_lp //denormalize the number - tstb %d1 //check flag - beqs no_inex //if clr, no inex - bras dnrm_inex //if set, set inex - -load_sgl: - movew #sgl_thresh,%d1 //put copy of threshold in d1 - movel %d1,%d0 //copy d1 into d0 - subw LOCAL_EX(%a0),%d0 //diff = threshold - exp - cmpw #67,%d0 //if diff > 67 (mant + grs bits) - bpls chk_stky //then branch (all bits would be -// ; shifted off in denorm routine) - clrl %d0 //else clear the sticky flag - bsr dnrm_lp //denormalize the number - tstb %d1 //check flag - beqs no_inex //if clr, no inex - bras dnrm_inex //if set, set inex - -chk_stky: - tstl LOCAL_HI(%a0) //check for any bits set - bnes set_stky - tstl LOCAL_LO(%a0) //check for any bits set - bnes set_stky - bras clr_mant -set_stky: - orl #inx2a_mask,USER_FPSR(%a6) //set inex2/ainex - movel #0x20000000,%d0 //set sticky bit in return value -clr_mant: - movew %d1,LOCAL_EX(%a0) //load exp with threshold - movel #0,LOCAL_HI(%a0) //set d1 = 0 (ms mantissa) - movel #0,LOCAL_LO(%a0) //set d2 = 0 (ms mantissa) - rts -dnrm_inex: - orl #inx2a_mask,USER_FPSR(%a6) //set inex2/ainex -no_inex: - rts - -// -// dnrm_lp --- normalize exponent/mantissa to specified threshold -// -// Input: -// a0 points to the operand to be denormalized -// d0{31:29} initial guard,round,sticky -// d1{15:0} denormalization threshold -// Output: -// a0 points to the denormalized operand -// d0{31:29} final guard,round,sticky -// d1.b inexact flag: all ones means inexact result -// -// The LOCAL_LO and LOCAL_GRS parts of the value are copied to FP_SCR2 -// so that bfext can be used to extract the new low part of the mantissa. -// Dnrm_lp can be called with a0 pointing to ETEMP or WBTEMP and there -// is no LOCAL_GRS scratch word following it on the fsave frame. -// - .global dnrm_lp -dnrm_lp: - movel %d2,-(%sp) //save d2 for temp use - btstb #E3,E_BYTE(%a6) //test for type E3 exception - beqs not_E3 //not type E3 exception - bfextu WBTEMP_GRS(%a6){#6:#3},%d2 //extract guard,round, sticky bit - movel #29,%d0 - lsll %d0,%d2 //shift g,r,s to their positions - movel %d2,%d0 -not_E3: - movel (%sp)+,%d2 //restore d2 - movel LOCAL_LO(%a0),FP_SCR2+LOCAL_LO(%a6) - movel %d0,FP_SCR2+LOCAL_GRS(%a6) - movel %d1,%d0 //copy the denorm threshold - subw LOCAL_EX(%a0),%d1 //d1 = threshold - uns exponent - bles no_lp //d1 <= 0 - cmpw #32,%d1 - blts case_1 //0 = d1 < 32 - cmpw #64,%d1 - blts case_2 //32 <= d1 < 64 - bra case_3 //d1 >= 64 -// -// No normalization necessary -// -no_lp: - clrb %d1 //set no inex2 reported - movel FP_SCR2+LOCAL_GRS(%a6),%d0 //restore original g,r,s - rts -// -// case (0<d1<32) -// -case_1: - movel %d2,-(%sp) - movew %d0,LOCAL_EX(%a0) //exponent = denorm threshold - movel #32,%d0 - subw %d1,%d0 //d0 = 32 - d1 - bfextu LOCAL_EX(%a0){%d0:#32},%d2 - bfextu %d2{%d1:%d0},%d2 //d2 = new LOCAL_HI - bfextu LOCAL_HI(%a0){%d0:#32},%d1 //d1 = new LOCAL_LO - bfextu FP_SCR2+LOCAL_LO(%a6){%d0:#32},%d0 //d0 = new G,R,S - movel %d2,LOCAL_HI(%a0) //store new LOCAL_HI - movel %d1,LOCAL_LO(%a0) //store new LOCAL_LO - clrb %d1 - bftst %d0{#2:#30} - beqs c1nstky - bsetl #rnd_stky_bit,%d0 - st %d1 -c1nstky: - movel FP_SCR2+LOCAL_GRS(%a6),%d2 //restore original g,r,s - andil #0xe0000000,%d2 //clear all but G,R,S - tstl %d2 //test if original G,R,S are clear - beqs grs_clear - orl #0x20000000,%d0 //set sticky bit in d0 -grs_clear: - andil #0xe0000000,%d0 //clear all but G,R,S - movel (%sp)+,%d2 - rts -// -// case (32<=d1<64) -// -case_2: - movel %d2,-(%sp) - movew %d0,LOCAL_EX(%a0) //unsigned exponent = threshold - subw #32,%d1 //d1 now between 0 and 32 - movel #32,%d0 - subw %d1,%d0 //d0 = 32 - d1 - bfextu LOCAL_EX(%a0){%d0:#32},%d2 - bfextu %d2{%d1:%d0},%d2 //d2 = new LOCAL_LO - bfextu LOCAL_HI(%a0){%d0:#32},%d1 //d1 = new G,R,S - bftst %d1{#2:#30} - bnes c2_sstky //bra if sticky bit to be set - bftst FP_SCR2+LOCAL_LO(%a6){%d0:#32} - bnes c2_sstky //bra if sticky bit to be set - movel %d1,%d0 - clrb %d1 - bras end_c2 -c2_sstky: - movel %d1,%d0 - bsetl #rnd_stky_bit,%d0 - st %d1 -end_c2: - clrl LOCAL_HI(%a0) //store LOCAL_HI = 0 - movel %d2,LOCAL_LO(%a0) //store LOCAL_LO - movel FP_SCR2+LOCAL_GRS(%a6),%d2 //restore original g,r,s - andil #0xe0000000,%d2 //clear all but G,R,S - tstl %d2 //test if original G,R,S are clear - beqs clear_grs - orl #0x20000000,%d0 //set sticky bit in d0 -clear_grs: - andil #0xe0000000,%d0 //get rid of all but G,R,S - movel (%sp)+,%d2 - rts -// -// d1 >= 64 Force the exponent to be the denorm threshold with the -// correct sign. -// -case_3: - movew %d0,LOCAL_EX(%a0) - tstw LOCAL_SGN(%a0) - bges c3con -c3neg: - orl #0x80000000,LOCAL_EX(%a0) -c3con: - cmpw #64,%d1 - beqs sixty_four - cmpw #65,%d1 - beqs sixty_five -// -// Shift value is out of range. Set d1 for inex2 flag and -// return a zero with the given threshold. -// - clrl LOCAL_HI(%a0) - clrl LOCAL_LO(%a0) - movel #0x20000000,%d0 - st %d1 - rts - -sixty_four: - movel LOCAL_HI(%a0),%d0 - bfextu %d0{#2:#30},%d1 - andil #0xc0000000,%d0 - bras c3com - -sixty_five: - movel LOCAL_HI(%a0),%d0 - bfextu %d0{#1:#31},%d1 - andil #0x80000000,%d0 - lsrl #1,%d0 //shift high bit into R bit - -c3com: - tstl %d1 - bnes c3ssticky - tstl LOCAL_LO(%a0) - bnes c3ssticky - tstb FP_SCR2+LOCAL_GRS(%a6) - bnes c3ssticky - clrb %d1 - bras c3end - -c3ssticky: - bsetl #rnd_stky_bit,%d0 - st %d1 -c3end: - clrl LOCAL_HI(%a0) - clrl LOCAL_LO(%a0) - rts - - |end |