1 # Copyright (c) 2012 The ANGLE Project Authors. All rights reserved. 2 # Use of this source code is governed by a BSD-style license that can be 3 # found in the LICENSE file. 4 # 5 6 # This script generates a function that converts 16-bit precision floating 7 # point numbers to 32-bit. 8 # It is based on ftp://ftp.fox-toolkit.org/pub/fasthalffloatconversion.pdf. 9 10 def convertMantissa(i): 11 if i == 0: 12 return 0 13 elif i < 1024: 14 m = i << 13 15 e = 0 16 while not (m & 0x00800000): 17 e -= 0x00800000 18 m = m << 1 19 m &= ~0x00800000 20 e += 0x38800000 21 return m | e 22 else: 23 return 0x38000000 + ((i - 1024) << 13) 24 25 def convertExponent(i): 26 if i == 0: 27 return 0 28 elif i in range(1, 31): 29 return i << 23 30 elif i == 31: 31 return 0x47800000 32 elif i == 32: 33 return 0x80000000 34 elif i in range(33, 63): 35 return 0x80000000 + ((i - 32) << 23) 36 else: 37 return 0xC7800000 38 39 def convertOffset(i): 40 if i == 0 or i == 32: 41 return 0 42 else: 43 return 1024 44 45 print """// 46 // Copyright (c) 2012 The ANGLE Project Authors. All rights reserved. 47 // Use of this source code is governed by a BSD-style license that can be 48 // found in the LICENSE file. 49 // 50 51 // This file is automatically generated. 52 53 namespace gl 54 { 55 """ 56 57 print "const static unsigned g_mantissa[2048] = {" 58 for i in range(0, 2048): 59 print " %#010x," % convertMantissa(i) 60 print "};\n" 61 62 print "const static unsigned g_exponent[64] = {" 63 for i in range(0, 64): 64 print " %#010x," % convertExponent(i) 65 print "};\n" 66 67 print "const static unsigned g_offset[64] = {" 68 for i in range(0, 64): 69 print " %#010x," % convertOffset(i) 70 print "};\n" 71 72 print """float float16ToFloat32(unsigned short h) 73 { 74 unsigned i32 = g_mantissa[g_offset[h >> 10] + (h & 0x3ff)] + g_exponent[h >> 10]; 75 return *(float*) &i32; 76 } 77 } 78 """ 79
