1 // Copyright 2015, ARM Limited
2 // All rights reserved.
3 //
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5 // modification, are permitted provided that the following conditions are met:
6 //
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8 //     this list of conditions and the following disclaimer.
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10 //     this list of conditions and the following disclaimer in the documentation
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14 //     specific prior written permission.
15 //
16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND
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20 // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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25 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 
27 #ifndef VIXL_UTILS_H
28 #define VIXL_UTILS_H
29 
30 #include <string.h>
31 #include <cmath>
32 #include "vixl/globals.h"
33 #include "vixl/compiler-intrinsics.h"
34 
35 namespace vixl {
36 
37 // Macros for compile-time format checking.
38 #if GCC_VERSION_OR_NEWER(4, 4, 0)
39 #define PRINTF_CHECK(format_index, varargs_index) \
40   __attribute__((format(gnu_printf, format_index, varargs_index)))
41 #else
42 #define PRINTF_CHECK(format_index, varargs_index)
43 #endif
44 
45 // Check number width.
is_intn(unsigned n,int64_t x)46 inline bool is_intn(unsigned n, int64_t x) {
47   VIXL_ASSERT((0 < n) && (n < 64));
48   int64_t limit = INT64_C(1) << (n - 1);
49   return (-limit <= x) && (x < limit);
50 }
51 
is_uintn(unsigned n,int64_t x)52 inline bool is_uintn(unsigned n, int64_t x) {
53   VIXL_ASSERT((0 < n) && (n < 64));
54   return !(x >> n);
55 }
56 
truncate_to_intn(unsigned n,int64_t x)57 inline uint32_t truncate_to_intn(unsigned n, int64_t x) {
58   VIXL_ASSERT((0 < n) && (n < 64));
59   return static_cast<uint32_t>(x & ((INT64_C(1) << n) - 1));
60 }
61 
62 #define INT_1_TO_63_LIST(V)                                                    \
63 V(1)  V(2)  V(3)  V(4)  V(5)  V(6)  V(7)  V(8)                                 \
64 V(9)  V(10) V(11) V(12) V(13) V(14) V(15) V(16)                                \
65 V(17) V(18) V(19) V(20) V(21) V(22) V(23) V(24)                                \
66 V(25) V(26) V(27) V(28) V(29) V(30) V(31) V(32)                                \
67 V(33) V(34) V(35) V(36) V(37) V(38) V(39) V(40)                                \
68 V(41) V(42) V(43) V(44) V(45) V(46) V(47) V(48)                                \
69 V(49) V(50) V(51) V(52) V(53) V(54) V(55) V(56)                                \
70 V(57) V(58) V(59) V(60) V(61) V(62) V(63)
71 
72 #define DECLARE_IS_INT_N(N)                                                    \
73 inline bool is_int##N(int64_t x) { return is_intn(N, x); }
74 #define DECLARE_IS_UINT_N(N)                                                   \
75 inline bool is_uint##N(int64_t x) { return is_uintn(N, x); }
76 #define DECLARE_TRUNCATE_TO_INT_N(N)                                           \
77 inline uint32_t truncate_to_int##N(int x) { return truncate_to_intn(N, x); }
78 INT_1_TO_63_LIST(DECLARE_IS_INT_N)
INT_1_TO_63_LIST(DECLARE_IS_UINT_N)79 INT_1_TO_63_LIST(DECLARE_IS_UINT_N)
80 INT_1_TO_63_LIST(DECLARE_TRUNCATE_TO_INT_N)
81 #undef DECLARE_IS_INT_N
82 #undef DECLARE_IS_UINT_N
83 #undef DECLARE_TRUNCATE_TO_INT_N
84 
85 // Bit field extraction.
86 inline uint32_t unsigned_bitextract_32(int msb, int lsb, uint32_t x) {
87   return (x >> lsb) & ((1 << (1 + msb - lsb)) - 1);
88 }
89 
unsigned_bitextract_64(int msb,int lsb,uint64_t x)90 inline uint64_t unsigned_bitextract_64(int msb, int lsb, uint64_t x) {
91   return (x >> lsb) & ((static_cast<uint64_t>(1) << (1 + msb - lsb)) - 1);
92 }
93 
signed_bitextract_32(int msb,int lsb,int32_t x)94 inline int32_t signed_bitextract_32(int msb, int lsb, int32_t x) {
95   return (x << (31 - msb)) >> (lsb + 31 - msb);
96 }
97 
signed_bitextract_64(int msb,int lsb,int64_t x)98 inline int64_t signed_bitextract_64(int msb, int lsb, int64_t x) {
99   return (x << (63 - msb)) >> (lsb + 63 - msb);
100 }
101 
102 // Floating point representation.
103 uint32_t float_to_rawbits(float value);
104 uint64_t double_to_rawbits(double value);
105 float rawbits_to_float(uint32_t bits);
106 double rawbits_to_double(uint64_t bits);
107 
108 uint32_t float_sign(float val);
109 uint32_t float_exp(float val);
110 uint32_t float_mantissa(float val);
111 uint32_t double_sign(double val);
112 uint32_t double_exp(double val);
113 uint64_t double_mantissa(double val);
114 
115 float float_pack(uint32_t sign, uint32_t exp, uint32_t mantissa);
116 double double_pack(uint64_t sign, uint64_t exp, uint64_t mantissa);
117 
118 // An fpclassify() function for 16-bit half-precision floats.
119 int float16classify(float16 value);
120 
121 // NaN tests.
IsSignallingNaN(double num)122 inline bool IsSignallingNaN(double num) {
123   const uint64_t kFP64QuietNaNMask = UINT64_C(0x0008000000000000);
124   uint64_t raw = double_to_rawbits(num);
125   if (std::isnan(num) && ((raw & kFP64QuietNaNMask) == 0)) {
126     return true;
127   }
128   return false;
129 }
130 
131 
IsSignallingNaN(float num)132 inline bool IsSignallingNaN(float num) {
133   const uint32_t kFP32QuietNaNMask = 0x00400000;
134   uint32_t raw = float_to_rawbits(num);
135   if (std::isnan(num) && ((raw & kFP32QuietNaNMask) == 0)) {
136     return true;
137   }
138   return false;
139 }
140 
141 
IsSignallingNaN(float16 num)142 inline bool IsSignallingNaN(float16 num) {
143   const uint16_t kFP16QuietNaNMask = 0x0200;
144   return (float16classify(num) == FP_NAN) &&
145          ((num & kFP16QuietNaNMask) == 0);
146 }
147 
148 
149 template <typename T>
IsQuietNaN(T num)150 inline bool IsQuietNaN(T num) {
151   return std::isnan(num) && !IsSignallingNaN(num);
152 }
153 
154 
155 // Convert the NaN in 'num' to a quiet NaN.
ToQuietNaN(double num)156 inline double ToQuietNaN(double num) {
157   const uint64_t kFP64QuietNaNMask = UINT64_C(0x0008000000000000);
158   VIXL_ASSERT(std::isnan(num));
159   return rawbits_to_double(double_to_rawbits(num) | kFP64QuietNaNMask);
160 }
161 
162 
ToQuietNaN(float num)163 inline float ToQuietNaN(float num) {
164   const uint32_t kFP32QuietNaNMask = 0x00400000;
165   VIXL_ASSERT(std::isnan(num));
166   return rawbits_to_float(float_to_rawbits(num) | kFP32QuietNaNMask);
167 }
168 
169 
170 // Fused multiply-add.
FusedMultiplyAdd(double op1,double op2,double a)171 inline double FusedMultiplyAdd(double op1, double op2, double a) {
172   return fma(op1, op2, a);
173 }
174 
175 
FusedMultiplyAdd(float op1,float op2,float a)176 inline float FusedMultiplyAdd(float op1, float op2, float a) {
177   return fmaf(op1, op2, a);
178 }
179 
180 
LowestSetBit(uint64_t value)181 inline uint64_t LowestSetBit(uint64_t value) {
182   return value & -value;
183 }
184 
185 
186 template<typename T>
HighestSetBitPosition(T value)187 inline int HighestSetBitPosition(T value) {
188   VIXL_ASSERT(value != 0);
189   return (sizeof(value) * 8 - 1) - CountLeadingZeros(value);
190 }
191 
192 
193 template<typename V>
WhichPowerOf2(V value)194 inline int WhichPowerOf2(V value) {
195   VIXL_ASSERT(IsPowerOf2(value));
196   return CountTrailingZeros(value);
197 }
198 
199 
200 unsigned CountClearHalfWords(uint64_t imm, unsigned reg_size);
201 
202 
203 template <typename T>
ReverseBits(T value)204 T ReverseBits(T value) {
205   VIXL_ASSERT((sizeof(value) == 1) || (sizeof(value) == 2) ||
206               (sizeof(value) == 4) || (sizeof(value) == 8));
207   T result = 0;
208   for (unsigned i = 0; i < (sizeof(value) * 8); i++) {
209     result = (result << 1) | (value & 1);
210     value >>= 1;
211   }
212   return result;
213 }
214 
215 
216 template <typename T>
ReverseBytes(T value,int block_bytes_log2)217 T ReverseBytes(T value, int block_bytes_log2) {
218   VIXL_ASSERT((sizeof(value) == 4) || (sizeof(value) == 8));
219   VIXL_ASSERT((1U << block_bytes_log2) <= sizeof(value));
220   // Split the 64-bit value into an 8-bit array, where b[0] is the least
221   // significant byte, and b[7] is the most significant.
222   uint8_t bytes[8];
223   uint64_t mask = UINT64_C(0xff00000000000000);
224   for (int i = 7; i >= 0; i--) {
225     bytes[i] = (static_cast<uint64_t>(value) & mask) >> (i * 8);
226     mask >>= 8;
227   }
228 
229   // Permutation tables for REV instructions.
230   //  permute_table[0] is used by REV16_x, REV16_w
231   //  permute_table[1] is used by REV32_x, REV_w
232   //  permute_table[2] is used by REV_x
233   VIXL_ASSERT((0 < block_bytes_log2) && (block_bytes_log2 < 4));
234   static const uint8_t permute_table[3][8] = { {6, 7, 4, 5, 2, 3, 0, 1},
235                                                {4, 5, 6, 7, 0, 1, 2, 3},
236                                                {0, 1, 2, 3, 4, 5, 6, 7} };
237   T result = 0;
238   for (int i = 0; i < 8; i++) {
239     result <<= 8;
240     result |= bytes[permute_table[block_bytes_log2 - 1][i]];
241   }
242   return result;
243 }
244 
245 
246 // Pointer alignment
247 // TODO: rename/refactor to make it specific to instructions.
248 template<typename T>
IsWordAligned(T pointer)249 bool IsWordAligned(T pointer) {
250   VIXL_ASSERT(sizeof(pointer) == sizeof(intptr_t));   // NOLINT(runtime/sizeof)
251   return ((intptr_t)(pointer) & 3) == 0;
252 }
253 
254 // Increment a pointer (up to 64 bits) until it has the specified alignment.
255 template<class T>
AlignUp(T pointer,size_t alignment)256 T AlignUp(T pointer, size_t alignment) {
257   // Use C-style casts to get static_cast behaviour for integral types (T), and
258   // reinterpret_cast behaviour for other types.
259 
260   uint64_t pointer_raw = (uint64_t)pointer;
261   VIXL_STATIC_ASSERT(sizeof(pointer) <= sizeof(pointer_raw));
262 
263   size_t align_step = (alignment - pointer_raw) % alignment;
264   VIXL_ASSERT((pointer_raw + align_step) % alignment == 0);
265 
266   return (T)(pointer_raw + align_step);
267 }
268 
269 // Decrement a pointer (up to 64 bits) until it has the specified alignment.
270 template<class T>
AlignDown(T pointer,size_t alignment)271 T AlignDown(T pointer, size_t alignment) {
272   // Use C-style casts to get static_cast behaviour for integral types (T), and
273   // reinterpret_cast behaviour for other types.
274 
275   uint64_t pointer_raw = (uint64_t)pointer;
276   VIXL_STATIC_ASSERT(sizeof(pointer) <= sizeof(pointer_raw));
277 
278   size_t align_step = pointer_raw % alignment;
279   VIXL_ASSERT((pointer_raw - align_step) % alignment == 0);
280 
281   return (T)(pointer_raw - align_step);
282 }
283 
284 }  // namespace vixl
285 
286 #endif  // VIXL_UTILS_H
287