Merge pull request #10 from And-Nob/master

Use clz instruction in riscv

libFDK/include/clz.h

@@ -109,6 +109,9 @@ [email protected]
 #if defined(__arm__)
 #include "arm/clz_arm.h"
 
+#elif defined(__riscv)
+#include "riscv/clz_riscv.h"
+
 #elif defined(__mips__)
 #include "mips/clz_mips.h"
 

libFDK/include/riscv/clz_riscv.h

@@ -0,0 +1,75 @@
+#if !defined(CLZ_RISCV_H)
+#define CLZ_RISCV_H
+
+#if defined(__riscv)
+
+#define FUNCTION_fixnormz_D
+#define FUNCTION_fixnorm_D
+#define FUNCTION_fixnormz_S
+#define FUNCTION_fixnorm_S
+
+#ifdef FUNCTION_fixnormz_D
+inline int fixnormz_D(long value) {
+    int result;
+
+    // asm volatile (
+    //     "li       %0, 0                    \n"  // Initialize leadingBits to 0
+    //     "not      t1, %1                   \n"  // Perform bitwise NOT on 'result'
+    //     "loop%=:                             \n"
+    //     "bgez     t1, end%=                  \n"  // If MSB is 0 (a is non-negative), break loop
+    //     "slli     t1, t1, 1                \n"  // Shift 'a' left by 1 bit (store result in t1)
+    //     "addi     %0, %0, 1                \n"  // Increment leadingBits
+    //     "j        loop%=                     \n"  // Repeat the loop
+    //     "end%=:                              \n"
+    //     : "=&r" (result) // Output operands
+    //     : "r" (value)
+    //     : "t1"                                         
+    // );
+
+    asm volatile(
+        // R_TYPE_INSTR(_f7, _rs2, _rs1, _f3, _rd, _opc)
+        // .word (((_f7) << 25) | ((_rs2) << 20) | ((_rs1) << 15) | ((_f3) << 12) | ((_rd) << 7) | (_opc))
+        "mv a0, %1 \n"
+        ".word (((0b0110000) << 25) | ((0b00000) << 20) | ((10) << 15) | ((0b001) << 12) | ((11) << 7) | (0b0010011)) \n" // a0 is register 10, a1 is register 11
+        "mv %0, a1 \n"
+        : "=r" (result) // output
+        : "r" (value) // input
+        : "a0", "a1"
+    );
+
+    return result;
+}
+#endif /* #ifdef FUNCTION_fixnormz_D */
+
+#ifdef FUNCTION_fixnorm_D
+inline INT fixnorm_D(LONG value) {
+  if (!value) return 0;
+  if (value < 0) value = ~value;
+  return fixnormz_D(value) - 1;
+}
+#endif /* #ifdef FUNCTION_fixnorm_D */
+
+#ifdef FUNCTION_fixnormz_S
+inline INT fixnormz_S(SHORT value) {
+  INT result;
+  result = (LONG)(value << 16);
+  if (result == 0)
+    result = 16;
+  else
+    result = fixnormz_D(result);
+  return result;
+}
+#endif /* #ifdef FUNCTION_fixnormz_S */
+
+#ifdef FUNCTION_fixnorm_S
+inline INT fixnorm_S(SHORT value) {
+  LONG lvalue = (LONG)(value << 16);
+  if (!lvalue) return 0;
+  if (lvalue < 0) lvalue = ~lvalue;
+  return fixnormz_D(lvalue) - 1;
+}
+#endif /* #ifdef FUNCTION_fixnorm_S */
+
+#endif /* __riscv */
+
+#endif /* !defined(CLZ_RISCV_H) */