URL https://opencores.org/ocsvn/openrisc/openrisc/trunk

Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [rtos/] [rtems/] [c/] [src/] [lib/] [libcpu/] [m68k/] [m68040/] [fpsp/] [srem_mod.S] - Blame information for rev 594

Go to most recent revision | Details | Compare with Previous | View Log


//
//      $Id: srem_mod.S,v 1.2 2001-09-27 12:01:22 chris Exp $
//
//      srem_mod.sa 3.1 12/10/90
//
//      The entry point sMOD computes the floating point MOD of the
//      input values X and Y. The entry point sREM computes the floating
//      point (IEEE) REM of the input values X and Y.
//
//      INPUT
//      -----
//      Double-extended value Y is pointed to by address in register
//      A0. Double-extended value X is located in -12(A0). The values
//      of X and Y are both nonzero and finite; although either or both
//      of them can be denormalized. The special cases of zeros, NaNs,
//      and infinities are handled elsewhere.
//
//      OUTPUT
//      ------
//      FREM(X,Y) or FMOD(X,Y), depending on entry point.
//
//       ALGORITHM
//       ---------
//
//       Step 1.  Save and strip signs of X and Y: signX := sign(X),
//                signY := sign(Y), X := |X|, Y := |Y|,
//                signQ := signX EOR signY. Record whether MOD or REM
//                is requested.
//
//       Step 2.  Set L := expo(X)-expo(Y), k := 0, Q := 0.
//                If (L < 0) then
//                   R := X, go to Step 4.
//                else
//                   R := 2^(-L)X, j := L.
//                endif
//
//       Step 3.  Perform MOD(X,Y)
//            3.1 If R = Y, go to Step 9.
//            3.2 If R > Y, then { R := R - Y, Q := Q + 1}
//            3.3 If j = 0, go to Step 4.
//            3.4 k := k + 1, j := j - 1, Q := 2Q, R := 2R. Go to
//                Step 3.1.
//
//       Step 4.  At this point, R = X - QY = MOD(X,Y). Set
//                Last_Subtract := false (used in Step 7 below). If
//                MOD is requested, go to Step 6.
//
//       Step 5.  R = MOD(X,Y), but REM(X,Y) is requested.
//            5.1 If R < Y/2, then R = MOD(X,Y) = REM(X,Y). Go to
//                Step 6.
//            5.2 If R > Y/2, then { set Last_Subtract := true,
//                Q := Q + 1, Y := signY*Y }. Go to Step 6.
//            5.3 This is the tricky case of R = Y/2. If Q is odd,
//                then { Q := Q + 1, signX := -signX }.
//
//       Step 6.  R := signX*R.
//
//       Step 7.  If Last_Subtract = true, R := R - Y.
//
//       Step 8.  Return signQ, last 7 bits of Q, and R as required.
//
//       Step 9.  At this point, R = 2^(-j)*X - Q Y = Y. Thus,
//                X = 2^(j)*(Q+1)Y. set Q := 2^(j)*(Q+1),
//                R := 0. Return signQ, last 7 bits of Q, and R.
//
//
 
//              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.
 
SREM_MOD:    //idnt    2,1 | Motorola 040 Floating Point Software Package
 
        |section    8
 
#include "fpsp.defs"
 
        .set    Mod_Flag,L_SCR3
        .set    SignY,FP_SCR3+4
        .set    SignX,FP_SCR3+8
        .set    SignQ,FP_SCR3+12
        .set    Sc_Flag,FP_SCR4
 
        .set    Y,FP_SCR1
        .set    Y_Hi,Y+4
        .set    Y_Lo,Y+8
 
        .set    R,FP_SCR2
        .set    R_Hi,R+4
        .set    R_Lo,R+8
 
 
Scale:     .long        0x00010000,0x80000000,0x00000000,0x00000000
 
        |xref   t_avoid_unsupp
 
        .global        smod
smod:
 
   movel               #0,Mod_Flag(%a6)
   bras                Mod_Rem
 
        .global        srem
srem:
 
   movel               #1,Mod_Flag(%a6)
 
Mod_Rem:
//..Save sign of X and Y
   moveml              %d2-%d7,-(%a7)     // ...save data registers
   movew               (%a0),%d3
   movew               %d3,SignY(%a6)
   andil               #0x00007FFF,%d3   // ...Y := |Y|
 
//
   movel               4(%a0),%d4
   movel               8(%a0),%d5        // ...(D3,D4,D5) is |Y|
 
   tstl                %d3
   bnes                Y_Normal
 
   movel               #0x00003FFE,%d3  // ...$3FFD + 1
   tstl                %d4
   bnes                HiY_not0
 
HiY_0:
   movel               %d5,%d4
   clrl                %d5
   subil               #32,%d3
   clrl                %d6
   bfffo                %d4{#0:#32},%d6
   lsll                %d6,%d4
   subl                %d6,%d3           // ...(D3,D4,D5) is normalized
//                                       ...with bias $7FFD
   bras                Chk_X
 
HiY_not0:
   clrl                %d6
   bfffo                %d4{#0:#32},%d6
   subl                %d6,%d3
   lsll                %d6,%d4
   movel               %d5,%d7           // ...a copy of D5
   lsll                %d6,%d5
   negl                %d6
   addil               #32,%d6
   lsrl                %d6,%d7
   orl                 %d7,%d4           // ...(D3,D4,D5) normalized
//                                       ...with bias $7FFD
   bras                Chk_X
 
Y_Normal:
   addil               #0x00003FFE,%d3   // ...(D3,D4,D5) normalized
//                                       ...with bias $7FFD
 
Chk_X:
   movew               -12(%a0),%d0
   movew               %d0,SignX(%a6)
   movew               SignY(%a6),%d1
   eorl                %d0,%d1
   andil               #0x00008000,%d1
   movew               %d1,SignQ(%a6)   // ...sign(Q) obtained
   andil               #0x00007FFF,%d0
   movel               -8(%a0),%d1
   movel               -4(%a0),%d2       // ...(D0,D1,D2) is |X|
   tstl                %d0
   bnes                X_Normal
   movel               #0x00003FFE,%d0
   tstl                %d1
   bnes                HiX_not0
 
HiX_0:
   movel               %d2,%d1
   clrl                %d2
   subil               #32,%d0
   clrl                %d6
   bfffo                %d1{#0:#32},%d6
   lsll                %d6,%d1
   subl                %d6,%d0           // ...(D0,D1,D2) is normalized
//                                       ...with bias $7FFD
   bras                Init
 
HiX_not0:
   clrl                %d6
   bfffo                %d1{#0:#32},%d6
   subl                %d6,%d0
   lsll                %d6,%d1
   movel               %d2,%d7           // ...a copy of D2
   lsll                %d6,%d2
   negl                %d6
   addil               #32,%d6
   lsrl                %d6,%d7
   orl                 %d7,%d1           // ...(D0,D1,D2) normalized
//                                       ...with bias $7FFD
   bras                Init
 
X_Normal:
   addil               #0x00003FFE,%d0   // ...(D0,D1,D2) normalized
//                                       ...with bias $7FFD
 
Init:
//
   movel               %d3,L_SCR1(%a6)   // ...save biased expo(Y)
   movel                %d0,L_SCR2(%a6) //save d0
   subl                %d3,%d0           // ...L := expo(X)-expo(Y)
//   Move.L               D0,L            ...D0 is j
   clrl                %d6              // ...D6 := carry <- 0
   clrl                %d3              // ...D3 is Q
   moveal              #0,%a1           // ...A1 is k; j+k=L, Q=0
 
//..(Carry,D1,D2) is R
   tstl                %d0
   bges                Mod_Loop
 
//..expo(X) < expo(Y). Thus X = mod(X,Y)
//
   movel                L_SCR2(%a6),%d0 //restore d0
   bra                Get_Mod
 
//..At this point  R = 2^(-L)X; Q = 0; k = 0; and  k+j = L
 
 
Mod_Loop:
   tstl                %d6              // ...test carry bit
   bgts                R_GT_Y
 
//..At this point carry = 0, R = (D1,D2), Y = (D4,D5)
   cmpl                %d4,%d1           // ...compare hi(R) and hi(Y)
   bnes                R_NE_Y
   cmpl                %d5,%d2           // ...compare lo(R) and lo(Y)
   bnes                R_NE_Y
 
//..At this point, R = Y
   bra                Rem_is_0
 
R_NE_Y:
//..use the borrow of the previous compare
   bcss                R_LT_Y          // ...borrow is set iff R < Y
 
R_GT_Y:
//..If Carry is set, then Y < (Carry,D1,D2) < 2Y. Otherwise, Carry = 0
//..and Y < (D1,D2) < 2Y. Either way, perform R - Y
   subl                %d5,%d2           // ...lo(R) - lo(Y)
   subxl               %d4,%d1           // ...hi(R) - hi(Y)
   clrl                %d6              // ...clear carry
   addql               #1,%d3           // ...Q := Q + 1
 
R_LT_Y:
//..At this point, Carry=0, R < Y. R = 2^(k-L)X - QY; k+j = L; j >= 0.
   tstl                %d0              // ...see if j = 0.
   beqs                PostLoop
 
   addl                %d3,%d3           // ...Q := 2Q
   addl                %d2,%d2           // ...lo(R) = 2lo(R)
   roxll               #1,%d1           // ...hi(R) = 2hi(R) + carry
   scs                  %d6              // ...set Carry if 2(R) overflows
   addql               #1,%a1           // ...k := k+1
   subql               #1,%d0           // ...j := j - 1
//..At this point, R=(Carry,D1,D2) = 2^(k-L)X - QY, j+k=L, j >= 0, R < 2Y.
 
   bras                Mod_Loop
 
PostLoop:
//..k = L, j = 0, Carry = 0, R = (D1,D2) = X - QY, R < Y.
 
//..normalize R.
   movel               L_SCR1(%a6),%d0           // ...new biased expo of R
   tstl                %d1
   bnes                HiR_not0
 
HiR_0:
   movel               %d2,%d1
   clrl                %d2
   subil               #32,%d0
   clrl                %d6
   bfffo                %d1{#0:#32},%d6
   lsll                %d6,%d1
   subl                %d6,%d0           // ...(D0,D1,D2) is normalized
//                                       ...with bias $7FFD
   bras                Get_Mod
 
HiR_not0:
   clrl                %d6
   bfffo                %d1{#0:#32},%d6
   bmis                Get_Mod         // ...already normalized
   subl                %d6,%d0
   lsll                %d6,%d1
   movel               %d2,%d7           // ...a copy of D2
   lsll                %d6,%d2
   negl                %d6
   addil               #32,%d6
   lsrl                %d6,%d7
   orl                 %d7,%d1           // ...(D0,D1,D2) normalized
 
//
Get_Mod:
   cmpil                #0x000041FE,%d0
   bges         No_Scale
Do_Scale:
   movew                %d0,R(%a6)
   clrw         R+2(%a6)
   movel                %d1,R_Hi(%a6)
   movel                %d2,R_Lo(%a6)
   movel                L_SCR1(%a6),%d6
   movew                %d6,Y(%a6)
   clrw         Y+2(%a6)
   movel                %d4,Y_Hi(%a6)
   movel                %d5,Y_Lo(%a6)
   fmovex               R(%a6),%fp0             // ...no exception
   movel                #1,Sc_Flag(%a6)
   bras         ModOrRem
No_Scale:
   movel                %d1,R_Hi(%a6)
   movel                %d2,R_Lo(%a6)
   subil                #0x3FFE,%d0
   movew                %d0,R(%a6)
   clrw         R+2(%a6)
   movel                L_SCR1(%a6),%d6
   subil                #0x3FFE,%d6
   movel                %d6,L_SCR1(%a6)
   fmovex               R(%a6),%fp0
   movew                %d6,Y(%a6)
   movel                %d4,Y_Hi(%a6)
   movel                %d5,Y_Lo(%a6)
   movel                #0,Sc_Flag(%a6)
 
//
 
 
ModOrRem:
   movel               Mod_Flag(%a6),%d6
   beqs                Fix_Sign
 
   movel               L_SCR1(%a6),%d6           // ...new biased expo(Y)
   subql               #1,%d6           // ...biased expo(Y/2)
   cmpl                %d6,%d0
   blts                Fix_Sign
   bgts                Last_Sub
 
   cmpl                %d4,%d1
   bnes                Not_EQ
   cmpl                %d5,%d2
   bnes                Not_EQ
   bra                Tie_Case
 
Not_EQ:
   bcss                Fix_Sign
 
Last_Sub:
//
   fsubx                Y(%a6),%fp0             // ...no exceptions
   addql               #1,%d3           // ...Q := Q + 1
 
//
 
Fix_Sign:
//..Get sign of X
   movew               SignX(%a6),%d6
   bges         Get_Q
   fnegx                %fp0
 
//..Get Q
//
Get_Q:
   clrl         %d6
   movew               SignQ(%a6),%d6        // ...D6 is sign(Q)
   movel               #8,%d7
   lsrl                %d7,%d6
   andil               #0x0000007F,%d3   // ...7 bits of Q
   orl                 %d6,%d3           // ...sign and bits of Q
   swap                 %d3
   fmovel              %fpsr,%d6
   andil               #0xFF00FFFF,%d6
   orl                 %d3,%d6
   fmovel              %d6,%fpsr         // ...put Q in fpsr
 
//
Restore:
   moveml              (%a7)+,%d2-%d7
   fmovel              USER_FPCR(%a6),%fpcr
   movel               Sc_Flag(%a6),%d0
   beqs                Finish
   fmulx                Scale(%pc),%fp0 // ...may cause underflow
   bra                  t_avoid_unsupp  //check for denorm as a
//                                      ;result of the scaling
 
Finish:
        fmovex          %fp0,%fp0               //capture exceptions & round
        rts
 
Rem_is_0:
//..R = 2^(-j)X - Q Y = Y, thus R = 0 and quotient = 2^j (Q+1)
   addql               #1,%d3
   cmpil               #8,%d0           // ...D0 is j
   bges                Q_Big
 
   lsll                %d0,%d3
   bras                Set_R_0
 
Q_Big:
   clrl                %d3
 
Set_R_0:
   fmoves               #0x00000000,%fp0
   movel                #0,Sc_Flag(%a6)
   bra                Fix_Sign
 
Tie_Case:
//..Check parity of Q
   movel               %d3,%d6
   andil               #0x00000001,%d6
   tstl                %d6
   beq                Fix_Sign  // ...Q is even
 
//..Q is odd, Q := Q + 1, signX := -signX
   addql               #1,%d3
   movew               SignX(%a6),%d6
   eoril               #0x00008000,%d6
   movew               %d6,SignX(%a6)
   bra                Fix_Sign
 
   //end

Browse

Tools

Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [rtos/] [rtems/] [c/] [src/] [lib/] [libcpu/] [m68k/] [m68040/] [fpsp/] [srem_mod.S] - Blame information for rev 594

Line No.	Rev	Author	Line
1	30	unneback	`//`
2			`// $Id: srem_mod.S,v 1.2 2001-09-27 12:01:22 chris Exp $`
3			`//`
4			`// srem_mod.sa 3.1 12/10/90`
5			`//`
6			`// The entry point sMOD computes the floating point MOD of the`
7			`// input values X and Y. The entry point sREM computes the floating`
8			`// point (IEEE) REM of the input values X and Y.`
9			`//`
10			`// INPUT`
11			`// -----`
12			`// Double-extended value Y is pointed to by address in register`
13			`// A0. Double-extended value X is located in -12(A0). The values`
14			`// of X and Y are both nonzero and finite; although either or both`
15			`// of them can be denormalized. The special cases of zeros, NaNs,`
16			`// and infinities are handled elsewhere.`
17			`//`
18			`// OUTPUT`
19			`// ------`
20			`// FREM(X,Y) or FMOD(X,Y), depending on entry point.`
21			`//`
22			`// ALGORITHM`
23			`// ---------`
24			`//`
25			`// Step 1. Save and strip signs of X and Y: signX := sign(X),`
26			`// signY := sign(Y), X := \|X\|, Y := \|Y\|,`
27			`// signQ := signX EOR signY. Record whether MOD or REM`
28			`// is requested.`
29			`//`
30			`// Step 2. Set L := expo(X)-expo(Y), k := 0, Q := 0.`
31			`// If (L < 0) then`
32			`// R := X, go to Step 4.`
33			`// else`
34			`// R := 2^(-L)X, j := L.`
35			`// endif`
36			`//`
37			`// Step 3. Perform MOD(X,Y)`
38			`// 3.1 If R = Y, go to Step 9.`
39			`// 3.2 If R > Y, then { R := R - Y, Q := Q + 1}`
40			`// 3.3 If j = 0, go to Step 4.`
41			`// 3.4 k := k + 1, j := j - 1, Q := 2Q, R := 2R. Go to`
42			`// Step 3.1.`
43			`//`
44			`// Step 4. At this point, R = X - QY = MOD(X,Y). Set`
45			`// Last_Subtract := false (used in Step 7 below). If`
46			`// MOD is requested, go to Step 6.`
47			`//`
48			`// Step 5. R = MOD(X,Y), but REM(X,Y) is requested.`
49			`// 5.1 If R < Y/2, then R = MOD(X,Y) = REM(X,Y). Go to`
50			`// Step 6.`
51			`// 5.2 If R > Y/2, then { set Last_Subtract := true,`
52			`// Q := Q + 1, Y := signY*Y }. Go to Step 6.`
53			`// 5.3 This is the tricky case of R = Y/2. If Q is odd,`
54			`// then { Q := Q + 1, signX := -signX }.`
55			`//`
56			`// Step 6. R := signX*R.`
57			`//`
58			`// Step 7. If Last_Subtract = true, R := R - Y.`
59			`//`
60			`// Step 8. Return signQ, last 7 bits of Q, and R as required.`
61			`//`
62			`// Step 9. At this point, R = 2^(-j)*X - Q Y = Y. Thus,`
63			`// X = 2^(j)(Q+1)Y. set Q := 2^(j)(Q+1),`
64			`// R := 0. Return signQ, last 7 bits of Q, and R.`
65			`//`
66			`//`
67
68			`// Copyright (C) Motorola, Inc. 1990`
69			`// All Rights Reserved`
70			`//`
71			`// THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA`
72			`// The copyright notice above does not evidence any`
73			`// actual or intended publication of such source code.`
74
75			`SREM_MOD: //idnt 2,1 \| Motorola 040 Floating Point Software Package`
76
77			`\|section 8`
78
79			`#include "fpsp.defs"`
80
81			`.set Mod_Flag,L_SCR3`
82			`.set SignY,FP_SCR3+4`
83			`.set SignX,FP_SCR3+8`
84			`.set SignQ,FP_SCR3+12`
85			`.set Sc_Flag,FP_SCR4`
86
87			`.set Y,FP_SCR1`
88			`.set Y_Hi,Y+4`
89			`.set Y_Lo,Y+8`
90
91			`.set R,FP_SCR2`
92			`.set R_Hi,R+4`
93			`.set R_Lo,R+8`
94
95
96			`Scale: .long 0x00010000,0x80000000,0x00000000,0x00000000`
97
98			`\|xref t_avoid_unsupp`
99
100			`.global smod`
101			`smod:`
102
103			`movel #0,Mod_Flag(%a6)`
104			`bras Mod_Rem`
105
106			`.global srem`
107			`srem:`
108
109			`movel #1,Mod_Flag(%a6)`
110
111			`Mod_Rem:`
112			`//..Save sign of X and Y`
113			`moveml %d2-%d7,-(%a7) // ...save data registers`
114			`movew (%a0),%d3`
115			`movew %d3,SignY(%a6)`
116			`andil #0x00007FFF,%d3 // ...Y := \|Y\|`
117
118			`//`
119			`movel 4(%a0),%d4`
120			`movel 8(%a0),%d5 // ...(D3,D4,D5) is \|Y\|`
121
122			`tstl %d3`
123			`bnes Y_Normal`
124
125			`movel #0x00003FFE,%d3 // ...$3FFD + 1`
126			`tstl %d4`
127			`bnes HiY_not0`
128
129			`HiY_0:`
130			`movel %d5,%d4`
131			`clrl %d5`
132			`subil #32,%d3`
133			`clrl %d6`
134			`bfffo %d4{#0:#32},%d6`
135			`lsll %d6,%d4`
136			`subl %d6,%d3 // ...(D3,D4,D5) is normalized`
137			`// ...with bias $7FFD`
138			`bras Chk_X`
139
140			`HiY_not0:`
141			`clrl %d6`
142			`bfffo %d4{#0:#32},%d6`
143			`subl %d6,%d3`
144			`lsll %d6,%d4`
145			`movel %d5,%d7 // ...a copy of D5`
146			`lsll %d6,%d5`
147			`negl %d6`
148			`addil #32,%d6`
149			`lsrl %d6,%d7`
150			`orl %d7,%d4 // ...(D3,D4,D5) normalized`
151			`// ...with bias $7FFD`
152			`bras Chk_X`
153
154			`Y_Normal:`
155			`addil #0x00003FFE,%d3 // ...(D3,D4,D5) normalized`
156			`// ...with bias $7FFD`
157
158			`Chk_X:`
159			`movew -12(%a0),%d0`
160			`movew %d0,SignX(%a6)`
161			`movew SignY(%a6),%d1`
162			`eorl %d0,%d1`
163			`andil #0x00008000,%d1`
164			`movew %d1,SignQ(%a6) // ...sign(Q) obtained`
165			`andil #0x00007FFF,%d0`
166			`movel -8(%a0),%d1`
167			`movel -4(%a0),%d2 // ...(D0,D1,D2) is \|X\|`
168			`tstl %d0`
169			`bnes X_Normal`
170			`movel #0x00003FFE,%d0`
171			`tstl %d1`
172			`bnes HiX_not0`
173
174			`HiX_0:`
175			`movel %d2,%d1`
176			`clrl %d2`
177			`subil #32,%d0`
178			`clrl %d6`
179			`bfffo %d1{#0:#32},%d6`
180			`lsll %d6,%d1`
181			`subl %d6,%d0 // ...(D0,D1,D2) is normalized`
182			`// ...with bias $7FFD`
183			`bras Init`
184
185			`HiX_not0:`
186			`clrl %d6`
187			`bfffo %d1{#0:#32},%d6`
188			`subl %d6,%d0`
189			`lsll %d6,%d1`
190			`movel %d2,%d7 // ...a copy of D2`
191			`lsll %d6,%d2`
192			`negl %d6`
193			`addil #32,%d6`
194			`lsrl %d6,%d7`
195			`orl %d7,%d1 // ...(D0,D1,D2) normalized`
196			`// ...with bias $7FFD`
197			`bras Init`
198
199			`X_Normal:`
200			`addil #0x00003FFE,%d0 // ...(D0,D1,D2) normalized`
201			`// ...with bias $7FFD`
202
203			`Init:`
204			`//`
205			`movel %d3,L_SCR1(%a6) // ...save biased expo(Y)`
206			`movel %d0,L_SCR2(%a6) //save d0`
207			`subl %d3,%d0 // ...L := expo(X)-expo(Y)`
208			`// Move.L D0,L ...D0 is j`
209			`clrl %d6 // ...D6 := carry <- 0`
210			`clrl %d3 // ...D3 is Q`
211			`moveal #0,%a1 // ...A1 is k; j+k=L, Q=0`
212
213			`//..(Carry,D1,D2) is R`
214			`tstl %d0`
215			`bges Mod_Loop`
216
217			`//..expo(X) < expo(Y). Thus X = mod(X,Y)`
218			`//`
219			`movel L_SCR2(%a6),%d0 //restore d0`
220			`bra Get_Mod`
221
222			`//..At this point R = 2^(-L)X; Q = 0; k = 0; and k+j = L`
223
224
225			`Mod_Loop:`
226			`tstl %d6 // ...test carry bit`
227			`bgts R_GT_Y`
228
229			`//..At this point carry = 0, R = (D1,D2), Y = (D4,D5)`
230			`cmpl %d4,%d1 // ...compare hi(R) and hi(Y)`
231			`bnes R_NE_Y`
232			`cmpl %d5,%d2 // ...compare lo(R) and lo(Y)`
233			`bnes R_NE_Y`
234
235			`//..At this point, R = Y`
236			`bra Rem_is_0`
237
238			`R_NE_Y:`
239			`//..use the borrow of the previous compare`
240			`bcss R_LT_Y // ...borrow is set iff R < Y`
241
242			`R_GT_Y:`
243			`//..If Carry is set, then Y < (Carry,D1,D2) < 2Y. Otherwise, Carry = 0`
244			`//..and Y < (D1,D2) < 2Y. Either way, perform R - Y`
245			`subl %d5,%d2 // ...lo(R) - lo(Y)`
246			`subxl %d4,%d1 // ...hi(R) - hi(Y)`
247			`clrl %d6 // ...clear carry`
248			`addql #1,%d3 // ...Q := Q + 1`
249
250			`R_LT_Y:`
251			`//..At this point, Carry=0, R < Y. R = 2^(k-L)X - QY; k+j = L; j >= 0.`
252			`tstl %d0 // ...see if j = 0.`
253			`beqs PostLoop`
254
255			`addl %d3,%d3 // ...Q := 2Q`
256			`addl %d2,%d2 // ...lo(R) = 2lo(R)`
257			`roxll #1,%d1 // ...hi(R) = 2hi(R) + carry`
258			`scs %d6 // ...set Carry if 2(R) overflows`
259			`addql #1,%a1 // ...k := k+1`
260			`subql #1,%d0 // ...j := j - 1`
261			`//..At this point, R=(Carry,D1,D2) = 2^(k-L)X - QY, j+k=L, j >= 0, R < 2Y.`
262
263			`bras Mod_Loop`
264
265			`PostLoop:`
266			`//..k = L, j = 0, Carry = 0, R = (D1,D2) = X - QY, R < Y.`
267
268			`//..normalize R.`
269			`movel L_SCR1(%a6),%d0 // ...new biased expo of R`
270			`tstl %d1`
271			`bnes HiR_not0`
272
273			`HiR_0:`
274			`movel %d2,%d1`
275			`clrl %d2`
276			`subil #32,%d0`
277			`clrl %d6`
278			`bfffo %d1{#0:#32},%d6`
279			`lsll %d6,%d1`
280			`subl %d6,%d0 // ...(D0,D1,D2) is normalized`
281			`// ...with bias $7FFD`
282			`bras Get_Mod`
283
284			`HiR_not0:`
285			`clrl %d6`
286			`bfffo %d1{#0:#32},%d6`
287			`bmis Get_Mod // ...already normalized`
288			`subl %d6,%d0`
289			`lsll %d6,%d1`
290			`movel %d2,%d7 // ...a copy of D2`
291			`lsll %d6,%d2`
292			`negl %d6`
293			`addil #32,%d6`
294			`lsrl %d6,%d7`
295			`orl %d7,%d1 // ...(D0,D1,D2) normalized`
296
297			`//`
298			`Get_Mod:`
299			`cmpil #0x000041FE,%d0`
300			`bges No_Scale`
301			`Do_Scale:`
302			`movew %d0,R(%a6)`
303			`clrw R+2(%a6)`
304			`movel %d1,R_Hi(%a6)`
305			`movel %d2,R_Lo(%a6)`
306			`movel L_SCR1(%a6),%d6`
307			`movew %d6,Y(%a6)`
308			`clrw Y+2(%a6)`
309			`movel %d4,Y_Hi(%a6)`
310			`movel %d5,Y_Lo(%a6)`
311			`fmovex R(%a6),%fp0 // ...no exception`
312			`movel #1,Sc_Flag(%a6)`
313			`bras ModOrRem`
314			`No_Scale:`
315			`movel %d1,R_Hi(%a6)`
316			`movel %d2,R_Lo(%a6)`
317			`subil #0x3FFE,%d0`
318			`movew %d0,R(%a6)`
319			`clrw R+2(%a6)`
320			`movel L_SCR1(%a6),%d6`
321			`subil #0x3FFE,%d6`
322			`movel %d6,L_SCR1(%a6)`
323			`fmovex R(%a6),%fp0`
324			`movew %d6,Y(%a6)`
325			`movel %d4,Y_Hi(%a6)`
326			`movel %d5,Y_Lo(%a6)`
327			`movel #0,Sc_Flag(%a6)`
328
329			`//`
330
331
332			`ModOrRem:`
333			`movel Mod_Flag(%a6),%d6`
334			`beqs Fix_Sign`
335
336			`movel L_SCR1(%a6),%d6 // ...new biased expo(Y)`
337			`subql #1,%d6 // ...biased expo(Y/2)`
338			`cmpl %d6,%d0`
339			`blts Fix_Sign`
340			`bgts Last_Sub`
341
342			`cmpl %d4,%d1`
343			`bnes Not_EQ`
344			`cmpl %d5,%d2`
345			`bnes Not_EQ`
346			`bra Tie_Case`
347
348			`Not_EQ:`
349			`bcss Fix_Sign`
350
351			`Last_Sub:`
352			`//`
353			`fsubx Y(%a6),%fp0 // ...no exceptions`
354			`addql #1,%d3 // ...Q := Q + 1`
355
356			`//`
357
358			`Fix_Sign:`
359			`//..Get sign of X`
360			`movew SignX(%a6),%d6`
361			`bges Get_Q`
362			`fnegx %fp0`
363
364			`//..Get Q`
365			`//`
366			`Get_Q:`
367			`clrl %d6`
368			`movew SignQ(%a6),%d6 // ...D6 is sign(Q)`
369			`movel #8,%d7`
370			`lsrl %d7,%d6`
371			`andil #0x0000007F,%d3 // ...7 bits of Q`
372			`orl %d6,%d3 // ...sign and bits of Q`
373			`swap %d3`
374			`fmovel %fpsr,%d6`
375			`andil #0xFF00FFFF,%d6`
376			`orl %d3,%d6`
377			`fmovel %d6,%fpsr // ...put Q in fpsr`
378
379			`//`
380			`Restore:`
381			`moveml (%a7)+,%d2-%d7`
382			`fmovel USER_FPCR(%a6),%fpcr`
383			`movel Sc_Flag(%a6),%d0`
384			`beqs Finish`
385			`fmulx Scale(%pc),%fp0 // ...may cause underflow`
386			`bra t_avoid_unsupp //check for denorm as a`
387			`// ;result of the scaling`
388
389			`Finish:`
390			`fmovex %fp0,%fp0 //capture exceptions & round`
391			`rts`
392
393			`Rem_is_0:`
394			`//..R = 2^(-j)X - Q Y = Y, thus R = 0 and quotient = 2^j (Q+1)`
395			`addql #1,%d3`
396			`cmpil #8,%d0 // ...D0 is j`
397			`bges Q_Big`
398
399			`lsll %d0,%d3`
400			`bras Set_R_0`
401
402			`Q_Big:`
403			`clrl %d3`
404
405			`Set_R_0:`
406			`fmoves #0x00000000,%fp0`
407			`movel #0,Sc_Flag(%a6)`
408			`bra Fix_Sign`
409
410			`Tie_Case:`
411			`//..Check parity of Q`
412			`movel %d3,%d6`
413			`andil #0x00000001,%d6`
414			`tstl %d6`
415			`beq Fix_Sign // ...Q is even`
416
417			`//..Q is odd, Q := Q + 1, signX := -signX`
418			`addql #1,%d3`
419			`movew SignX(%a6),%d6`
420			`eoril #0x00008000,%d6`
421			`movew %d6,SignX(%a6)`
422			`bra Fix_Sign`
423
424			`//end`