init commit

2026-08-25 17:27:34 +00:00 · 2026-06-22 11:39:50 +03:00
commit ba6f1bde22
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+/* Reed-Solomon encoder
+ * Copyright 2004, Phil Karn, KA9Q
+ * May be used under the terms of the GNU Lesser General Public License (LGPL)
+ */
+#include <string.h>
+#include "fixed.h"
+#ifdef __VEC__
+#include <sys/sysctl.h>
+#endif
+
+
+static enum {UNKNOWN=0,MMX,SSE,SSE2,ALTIVEC,PORT} cpu_mode;
+
+static void encode_rs_8_c(data_t *data, data_t *parity,int pad);
+#if __vec__
+static void encode_rs_8_av(data_t *data, data_t *parity,int pad);
+#endif
+#if __i386__
+int cpu_features(void);
+#endif
+
+void encode_rs_8(data_t *data, data_t *parity,int pad){
+  if(cpu_mode == UNKNOWN){
+#ifdef __i386__
+    int f;
+    /* Figure out what kind of CPU we have */
+    f = cpu_features();
+    if(f & (1<<26)){ /* SSE2 is present */
+      cpu_mode = SSE2;
+    } else if(f & (1<<25)){ /* SSE is present */
+      cpu_mode = SSE;
+    } else if(f & (1<<23)){ /* MMX is present */
+      cpu_mode = MMX;
+    } else { /* No SIMD at all */
+      cpu_mode = PORT;
+    }
+#elif __VEC__
+    /* Ask the OS if we have Altivec support */
+    int selectors[2] = { CTL_HW, HW_VECTORUNIT };
+    int hasVectorUnit = 0;
+    size_t length = sizeof(hasVectorUnit);
+    int error = sysctl(selectors, 2, &hasVectorUnit, &length, NULL, 0);
+    if(0 == error && hasVectorUnit)
+      cpu_mode = ALTIVEC;
+    else
+      cpu_mode = PORT;
+#else
+    cpu_mode = PORT;
+#endif
+  }
+  switch(cpu_mode){
+#if __vec__
+  case ALTIVEC:
+    encode_rs_8_av(data,parity,pad);
+    return;
+#endif
+#if __i386__
+  case MMX:
+  case SSE:
+  case SSE2:
+#endif
+  default:
+    encode_rs_8_c(data,parity,pad);
+    return;
+  }
+}
+
+#if __vec__ /* PowerPC G4/G5 Altivec instructions are available */
+
+static vector unsigned char reverse = (vector unsigned char)(0,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1);
+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);
+
+/* Lookup table for feedback multiplications
+ * These are the low half of the coefficients. Since the generator polynomial is
+ * palindromic, we form the other half by reversing this one
+ */
+extern static union { vector unsigned char v; unsigned char c[16]; } table[256];
+
+static void encode_rs_8_av(data_t *data, data_t *parity,int pad){
+  union { vector unsigned char v[2]; unsigned char c[32]; } shift_register;
+  int i;
+
+  shift_register.v[0] = (vector unsigned char)(0);
+  shift_register.v[1] = (vector unsigned char)(0);
+  
+  for(i=0;i<NN-NROOTS-pad;i++){
+    vector unsigned char feedback0,feedback1;
+    unsigned char f;
+
+    f = data[i] ^ shift_register.c[31];
+    feedback1 = table[f].v;
+    feedback0 = vec_perm(feedback1,feedback1,reverse);
+
+    /* Shift right one byte */
+    shift_register.v[1] = vec_perm(shift_register.v[0],shift_register.v[1],shift_right) ^ feedback1;
+    shift_register.v[0] = vec_sro(shift_register.v[0],(vector unsigned char)(8)) ^ feedback0;
+    shift_register.c[0] = f;
+  }
+  for(i=0;i<NROOTS;i++)
+    parity[NROOTS-i-1] = shift_register.c[i];
+}
+#endif
+
+/* Portable C version */
+static void encode_rs_8_c(data_t *data, data_t *parity,int pad){
+
+#include "encode_rs.h"
+
+}