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1 /* Reed-Solomon encoder
2  * Copyright 2004, Phil Karn, KA9Q
3  * May be used under the terms of the GNU Lesser General Public License (LGPL)
4  */
5 #include <string.h>
6 #include "fixed.h"
7 #ifdef __VEC__
8 #include <sys/sysctl.h>
9 #endif
10 
11 
12 static enum {UNKNOWN=0,MMX,SSE,SSE2,ALTIVEC,PORT} cpu_mode;
13 
14 static void encode_rs_8_c(data_t *data, data_t *parity,int pad);
15 #if __vec__
16 static void encode_rs_8_av(data_t *data, data_t *parity,int pad);
17 #endif
18 #if __i386__
19 int cpu_features(void);
20 #endif
21 
encode_rs_8(data_t * data,data_t * parity,int pad)22 void encode_rs_8(data_t *data, data_t *parity,int pad){
23   if(cpu_mode == UNKNOWN){
24 #ifdef __i386__
25     int f;
26     /* Figure out what kind of CPU we have */
27     f = cpu_features();
28     if(f & (1<<26)){ /* SSE2 is present */
29       cpu_mode = SSE2;
30     } else if(f & (1<<25)){ /* SSE is present */
31       cpu_mode = SSE;
32     } else if(f & (1<<23)){ /* MMX is present */
33       cpu_mode = MMX;
34     } else { /* No SIMD at all */
35       cpu_mode = PORT;
36     }
37 #elif __VEC__
38     /* Ask the OS if we have Altivec support */
39     int selectors[2] = { CTL_HW, HW_VECTORUNIT };
40     int hasVectorUnit = 0;
41     size_t length = sizeof(hasVectorUnit);
42     int error = sysctl(selectors, 2, &hasVectorUnit, &length, NULL, 0);
43     if(0 == error && hasVectorUnit)
44       cpu_mode = ALTIVEC;
45     else
46       cpu_mode = PORT;
47 #else
48     cpu_mode = PORT;
49 #endif
50   }
51   switch(cpu_mode){
52 #if __vec__
53   case ALTIVEC:
54     encode_rs_8_av(data,parity,pad);
55     return;
56 #endif
57 #if __i386__
58   case MMX:
59   case SSE:
60   case SSE2:
61 #endif
62   default:
63     encode_rs_8_c(data,parity,pad);
64     return;
65   }
66 }
67 
68 #if __vec__ /* PowerPC G4/G5 Altivec instructions are available */
69 
70 static vector unsigned char reverse = (vector unsigned char)(0,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1);
71 static vector unsigned char shift_right = (vector unsigned char)(15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30);
72 
73 /* Lookup table for feedback multiplications
74  * These are the low half of the coefficients. Since the generator polynomial is
75  * palindromic, we form the other half by reversing this one
76  */
77 extern static union { vector unsigned char v; unsigned char c[16]; } table[256];
78 
encode_rs_8_av(data_t * data,data_t * parity,int pad)79 static void encode_rs_8_av(data_t *data, data_t *parity,int pad){
80   union { vector unsigned char v[2]; unsigned char c[32]; } shift_register;
81   int i;
82 
83   shift_register.v[0] = (vector unsigned char)(0);
84   shift_register.v[1] = (vector unsigned char)(0);
85 
86   for(i=0;i<NN-NROOTS-pad;i++){
87     vector unsigned char feedback0,feedback1;
88     unsigned char f;
89 
90     f = data[i] ^ shift_register.c[31];
91     feedback1 = table[f].v;
92     feedback0 = vec_perm(feedback1,feedback1,reverse);
93 
94     /* Shift right one byte */
95     shift_register.v[1] = vec_perm(shift_register.v[0],shift_register.v[1],shift_right) ^ feedback1;
96     shift_register.v[0] = vec_sro(shift_register.v[0],(vector unsigned char)(8)) ^ feedback0;
97     shift_register.c[0] = f;
98   }
99   for(i=0;i<NROOTS;i++)
100     parity[NROOTS-i-1] = shift_register.c[i];
101 }
102 #endif
103 
104 /* Portable C version */
encode_rs_8_c(data_t * data,data_t * parity,int pad)105 static void encode_rs_8_c(data_t *data, data_t *parity,int pad){
106 
107 #include "encode_rs.h"
108 
109 }
110