michael@0: # Copyright (c) 2012 The ANGLE Project Authors. All rights reserved.
michael@0: # Use of this source code is governed by a BSD-style license that can be
michael@0: # found in the LICENSE file.
michael@0: #
michael@0: 
michael@0: # This script generates a function that converts 16-bit precision floating
michael@0: # point numbers to 32-bit.
michael@0: # It is based on ftp://ftp.fox-toolkit.org/pub/fasthalffloatconversion.pdf.
michael@0: 
michael@0: def convertMantissa(i):
michael@0:     if i == 0:
michael@0:         return 0
michael@0:     elif i < 1024:
michael@0:         m = i << 13
michael@0:         e = 0
michael@0:         while not (m & 0x00800000):
michael@0:             e -= 0x00800000
michael@0:             m = m << 1
michael@0:         m &= ~0x00800000
michael@0:         e += 0x38800000
michael@0:         return m | e
michael@0:     else:
michael@0:         return 0x38000000 + ((i - 1024) << 13)
michael@0: 
michael@0: def convertExponent(i):
michael@0:     if i == 0:
michael@0:         return 0
michael@0:     elif i in range(1, 31):
michael@0:         return i << 23
michael@0:     elif i == 31:
michael@0:         return 0x47800000
michael@0:     elif i == 32:
michael@0:         return 0x80000000
michael@0:     elif i in range(33, 63):
michael@0:         return 0x80000000 + ((i - 32) << 23)
michael@0:     else:
michael@0:         return 0xC7800000
michael@0: 
michael@0: def convertOffset(i):
michael@0:     if i == 0 or i == 32:
michael@0:         return 0
michael@0:     else:
michael@0:         return 1024
michael@0: 
michael@0: print """//
michael@0: // Copyright (c) 2012 The ANGLE Project Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: //
michael@0: 
michael@0: // This file is automatically generated.
michael@0: 
michael@0: namespace gl
michael@0: {
michael@0: """
michael@0: 
michael@0: print "const static unsigned g_mantissa[2048] = {"
michael@0: for i in range(0, 2048):
michael@0:     print "    %#010x," % convertMantissa(i)
michael@0: print "};\n"
michael@0: 
michael@0: print "const static unsigned g_exponent[64] = {"
michael@0: for i in range(0, 64):
michael@0:     print "    %#010x," % convertExponent(i)
michael@0: print "};\n"
michael@0: 
michael@0: print "const static unsigned g_offset[64] = {"
michael@0: for i in range(0, 64):
michael@0:     print "    %#010x," % convertOffset(i)
michael@0: print "};\n"
michael@0: 
michael@0: print """float float16ToFloat32(unsigned short h)
michael@0: {
michael@0:     unsigned i32 = g_mantissa[g_offset[h >> 10] + (h & 0x3ff)] + g_exponent[h >> 10];
michael@0:     return *(float*) &i32;
michael@0: }
michael@0: }
michael@0: """