nanocoat/lib/base/fixed.c

   1 /* -*- Mode: C; indent-tabs-mode: t; tab-width: 4 -*-
   2 // ---------------------------------------------------------------------------
   3 // SquirrelJME
   4 //     Copyright (C) Stephanie Gawroriski <xer@multiphasicapps.net>
   5 // ---------------------------------------------------------------------------
   6 // SquirrelJME is under the Mozilla Public License Version 2.0.
   7 // See license.mkd for licensing and copyright information.
   8 // -------------------------------------------------------------------------*/
   9
  10 #include "sjme/fixed.h"
  11
  12 /** The number of bits to shift for fractions. */
  13 #define SJME_FIXED_SHIFT 16
  14
  15 /** The number of bits in an entire fixed value. */
  16 #define SJME_FIXED_FULL_BITS 32
  17
  18 /** The value one. */
  19 #define SJME_FIXED_ONE 0x10000
  20
  21 /** The masked for shifted values. */
  22 #define SJME_FIXED_MASK 0xFFFF
  23
  24 /** The masked for rounding values. */
  25 #define SJME_FIXED_ROUND_MASK 0x800
  26
  27 sjme_fixed sjme_fixed_ceil(
  28         sjme_attrInValue sjme_jint v)
  29 {
  30         sjme_fixed z;
  31
  32         z = v & (~SJME_FIXED_MASK);
  33         if ((v & SJME_FIXED_MASK) != 0)
  34                 return z + SJME_FIXED_ONE;
  35         return z;
  36 }
  37
  38 sjme_fixed sjme_fixed_div(
  39         sjme_attrInValue sjme_fixed num,
  40         sjme_attrInValue sjme_fixed den)
  41 {
  42         if (den == 0)
  43                 return 0;
  44
  45         return (sjme_fixed)((((int64_t)num) << SJME_FIXED_SHIFT) / den);
  46 }
  47
  48 sjme_fixed sjme_fixed_floor(
  49         sjme_attrInValue sjme_jint v)
  50 {
  51         return v & (~SJME_FIXED_MASK);
  52 }
  53
  54 sjme_fixed sjme_fixed_fraction(
  55         sjme_attrInValue sjme_jint num,
  56         sjme_attrInValue sjme_jint den)
  57 {
  58         if (den == 0)
  59                 return 0;
  60
  61         return sjme_fixed_div(sjme_fixed_hi(num),
  62                 sjme_fixed_hi(den));
  63 }
  64
  65 sjme_fixed sjme_fixed_hi(
  66         sjme_attrInValue sjme_jint val)
  67 {
  68         return val << SJME_FIXED_SHIFT;
  69 }
  70
  71 sjme_jint sjme_fixed_int(
  72         sjme_attrInValue sjme_fixed val)
  73 {
  74         return val >> SJME_FIXED_SHIFT;
  75 }
  76
  77 sjme_fixed sjme_fixed_mul(
  78         sjme_attrInValue sjme_fixed a,
  79         sjme_attrInValue sjme_fixed b)
  80 {
  81         return (sjme_fixed)(((int64_t)a) * ((int64_t)b) >> SJME_FIXED_SHIFT);
  82 }
  83
  84 sjme_fixed sjme_fixed_round(
  85         sjme_attrInValue sjme_jint v)
  86 {
  87         if (((v & SJME_FIXED_ROUND_MASK) != 0) == (v < 0))
  88                 return sjme_fixed_ceil(v);
  89         return sjme_fixed_floor(v);
  90 }