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1da177e4 LT |
1 | /* |
2 | * Copyright (C) 2000 Hewlett-Packard Co | |
3 | * Copyright (C) 2000 David Mosberger-Tang <davidm@hpl.hp.com> | |
4 | * | |
5 | * 32-bit integer division. | |
6 | * | |
7 | * This code is based on the application note entitled "Divide, Square Root | |
8 | * and Remainder Algorithms for the IA-64 Architecture". This document | |
9 | * is available as Intel document number 248725-002 or via the web at | |
10 | * http://developer.intel.com/software/opensource/numerics/ | |
11 | * | |
12 | * For more details on the theory behind these algorithms, see "IA-64 | |
13 | * and Elementary Functions" by Peter Markstein; HP Professional Books | |
14 | * (http://www.hp.com/go/retailbooks/) | |
15 | */ | |
16 | ||
17 | #include <asm/asmmacro.h> | |
18 | ||
19 | #ifdef MODULO | |
20 | # define OP mod | |
21 | #else | |
22 | # define OP div | |
23 | #endif | |
24 | ||
25 | #ifdef UNSIGNED | |
26 | # define SGN u | |
27 | # define EXTEND zxt4 | |
28 | # define INT_TO_FP(a,b) fcvt.xuf.s1 a=b | |
29 | # define FP_TO_INT(a,b) fcvt.fxu.trunc.s1 a=b | |
30 | #else | |
31 | # define SGN | |
32 | # define EXTEND sxt4 | |
33 | # define INT_TO_FP(a,b) fcvt.xf a=b | |
34 | # define FP_TO_INT(a,b) fcvt.fx.trunc.s1 a=b | |
35 | #endif | |
36 | ||
37 | #define PASTE1(a,b) a##b | |
38 | #define PASTE(a,b) PASTE1(a,b) | |
39 | #define NAME PASTE(PASTE(__,SGN),PASTE(OP,si3)) | |
40 | ||
41 | GLOBAL_ENTRY(NAME) | |
42 | .regstk 2,0,0,0 | |
43 | // Transfer inputs to FP registers. | |
44 | mov r2 = 0xffdd // r2 = -34 + 65535 (fp reg format bias) | |
45 | EXTEND in0 = in0 // in0 = a | |
46 | EXTEND in1 = in1 // in1 = b | |
47 | ;; | |
48 | setf.sig f8 = in0 | |
49 | setf.sig f9 = in1 | |
50 | #ifdef MODULO | |
51 | sub in1 = r0, in1 // in1 = -b | |
52 | #endif | |
53 | ;; | |
54 | // Convert the inputs to FP, to avoid FP software-assist faults. | |
55 | INT_TO_FP(f8, f8) | |
56 | INT_TO_FP(f9, f9) | |
57 | ;; | |
58 | setf.exp f7 = r2 // f7 = 2^-34 | |
59 | frcpa.s1 f6, p6 = f8, f9 // y0 = frcpa(b) | |
60 | ;; | |
61 | (p6) fmpy.s1 f8 = f8, f6 // q0 = a*y0 | |
62 | (p6) fnma.s1 f6 = f9, f6, f1 // e0 = -b*y0 + 1 | |
63 | ;; | |
64 | #ifdef MODULO | |
65 | setf.sig f9 = in1 // f9 = -b | |
66 | #endif | |
67 | (p6) fma.s1 f8 = f6, f8, f8 // q1 = e0*q0 + q0 | |
68 | (p6) fma.s1 f6 = f6, f6, f7 // e1 = e0*e0 + 2^-34 | |
69 | ;; | |
70 | #ifdef MODULO | |
71 | setf.sig f7 = in0 | |
72 | #endif | |
73 | (p6) fma.s1 f6 = f6, f8, f8 // q2 = e1*q1 + q1 | |
74 | ;; | |
75 | FP_TO_INT(f6, f6) // q = trunc(q2) | |
76 | ;; | |
77 | #ifdef MODULO | |
78 | xma.l f6 = f6, f9, f7 // r = q*(-b) + a | |
79 | ;; | |
80 | #endif | |
81 | getf.sig r8 = f6 // transfer result to result register | |
82 | br.ret.sptk.many rp | |
83 | END(NAME) |