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1 #ifndef CYGONCE_KERNEL_MFIXIMPL_INL |
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2 #define CYGONCE_KERNEL_MFIXIMPL_INL |
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3 |
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4 //========================================================================== |
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5 // |
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6 // mfiximpl.inl |
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7 // |
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8 // Memory pool with fixed block class declarations |
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9 // |
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10 //========================================================================== |
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11 //####COPYRIGHTBEGIN#### |
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12 // |
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13 // ------------------------------------------- |
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14 // The contents of this file are subject to the Cygnus eCos Public License |
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15 // Version 1.0 (the "License"); you may not use this file except in |
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16 // compliance with the License. You may obtain a copy of the License at |
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17 // http://sourceware.cygnus.com/ecos |
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18 // |
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19 // Software distributed under the License is distributed on an "AS IS" |
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20 // basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the |
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21 // License for the specific language governing rights and limitations under |
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22 // the License. |
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23 // |
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24 // The Original Code is eCos - Embedded Cygnus Operating System, released |
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25 // September 30, 1998. |
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26 // |
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27 // The Initial Developer of the Original Code is Cygnus. Portions created |
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28 // by Cygnus are Copyright (C) 1998,1999 Cygnus Solutions. All Rights Reserved. |
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29 // ------------------------------------------- |
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30 // |
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31 //####COPYRIGHTEND#### |
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32 //========================================================================== |
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33 //#####DESCRIPTIONBEGIN#### |
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34 // |
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35 // Author(s): hmt |
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36 // Contributors: hmt |
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37 // Date: 1998-03-23 |
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38 // Purpose: Define Mfiximpl class interface |
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39 // Description: Inline class for constructing a fixed block allocator |
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40 // Usage: #include <cyg/kernel/mfiximpl.hxx> |
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41 // #include <cyg/kernel/mfiximpl.inl> |
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42 // |
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43 //####DESCRIPTIONEND#### |
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44 // |
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45 //========================================================================== |
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46 |
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47 #include <cyg/hal/hal_arch.h> // HAL_LSBIT_INDEX magic asm code |
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48 |
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49 |
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50 Cyg_Mempool_Fixed_Implementation::Cyg_Mempool_Fixed_Implementation( |
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51 cyg_uint8 *base, |
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52 cyg_int32 size, |
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53 CYG_ADDRWORD alloc_unit ) |
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54 { |
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55 cyg_int32 i; |
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56 bitmap = (cyg_uint32 *)base; |
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57 blocksize = alloc_unit; |
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58 |
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59 CYG_ASSERT( blocksize > 0, "Bad blocksize" ); |
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60 CYG_ASSERT( size > 2, "Bad blocksize" ); |
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61 CYG_ASSERT( blocksize < size, "blocksize, size bad" ); |
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62 |
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63 numblocks = size / blocksize; |
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64 top = base + size; |
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65 |
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66 CYG_ASSERT( numblocks >= 2, "numblocks bad" ); |
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67 |
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68 i = (numblocks + 31)/32; // number of words to map blocks |
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69 while ( (i * 4 + numblocks * blocksize) > size ) { |
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70 numblocks --; // steal one block for admin |
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71 i = (numblocks + 31)/32; // number of words to map blocks |
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72 } |
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73 |
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74 CYG_ASSERT( 0 < i, "Bad word count for bitmap after fitment" ); |
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75 CYG_ASSERT( 0 < numblocks, "Bad block count after fitment" ); |
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76 |
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77 maptop = i; |
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78 // this should leave space for the bitmap and maintain alignment |
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79 mempool = top - (numblocks * blocksize); |
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80 CYG_ASSERT( base < mempool && mempool < top, "mempool escaped" ); |
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81 CYG_ASSERT( (cyg_uint8 *)(&bitmap[ maptop ]) <= mempool, |
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82 "mempool overwrites bitmap" ); |
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83 CYG_ASSERT( &mempool[ numblocks * blocksize ] <= top, |
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84 "mempool overflows top" ); |
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85 freeblocks = numblocks; |
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86 firstfree = 0; |
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87 |
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88 // clear out the bitmap; no blocks allocated yet |
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89 for ( i = 0; i < maptop; i++ ) |
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90 bitmap[ i ] = 0; |
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91 // apart from the non-existent ones at the top |
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92 for ( i = ((numblocks-1)&31) + 1; i < 32; i++ ) |
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93 bitmap[ maptop - 1 ] |= ( 1 << i ); |
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94 } |
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95 |
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96 Cyg_Mempool_Fixed_Implementation::~Cyg_Mempool_Fixed_Implementation() |
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97 { |
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98 } |
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99 |
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100 inline cyg_uint8 * |
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101 Cyg_Mempool_Fixed_Implementation::alloc( cyg_int32 size ) |
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102 { |
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103 // size parameter is not used |
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104 CYG_UNUSED_PARAM( cyg_int32, size ); |
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105 if ( 0 >= freeblocks ) |
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106 return NULL; |
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107 cyg_int32 i = firstfree; |
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108 cyg_uint8 *p = NULL; |
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109 do { |
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110 if ( 0xffffffff != bitmap[ i ] ) { |
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111 // then there is a free block in this bucket |
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112 register cyg_uint32 j, k; |
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113 k = ~bitmap[ i ]; // look for a 1 in complement |
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114 HAL_LSBIT_INDEX( j, k ); |
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115 CYG_ASSERT( 0 <= j && j <= 31, "Bad bit index" ); |
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116 CYG_ASSERT( 0 == (bitmap[ i ] & (1 << j)), "Found bit not clear" ); |
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117 bitmap[ i ] |= (1 << j); // set it allocated |
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118 firstfree = i; |
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119 freeblocks--; |
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120 CYG_ASSERT( freeblocks >= 0, "allocated too many" ); |
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121 p = &mempool[ ((32 * i) + j) * blocksize ]; |
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122 break; |
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123 } |
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124 if ( ++i >= maptop ) |
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125 i = 0; // wrap if at top |
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126 } while ( i != firstfree ); // prevent hang if internal error |
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127 CYG_ASSERT( NULL != p, "Should have a block here" ); |
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128 CYG_ASSERT( mempool <= p && p <= top, "alloc mem escaped" ); |
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129 return p; |
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130 } |
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131 |
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132 inline cyg_bool |
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133 Cyg_Mempool_Fixed_Implementation::free( cyg_uint8 *p, cyg_int32 size ) |
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134 { |
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135 // size parameter is not used |
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136 CYG_UNUSED_PARAM( cyg_int32, size ); |
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137 if ( p < mempool || p >= top ) |
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138 return false; // address way out of bounds |
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139 cyg_int32 i = p - mempool; |
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140 i = i / blocksize; |
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141 if ( &mempool[ i * blocksize ] != p ) |
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142 return false; // address not aligned |
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143 cyg_int32 j = i / 32; |
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144 CYG_ASSERT( 0 <= j && j < maptop, "map index escaped" ); |
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145 i = i - 32 * j; |
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146 CYG_ASSERT( 0 <= i && i < 32, "map bit index escaped" ); |
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147 if ( ! ((1 << i) & bitmap[ j ] ) ) |
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148 return false; // block was not allocated |
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149 bitmap[ j ] &=~(1 << i); // clear the bit |
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150 freeblocks++; // count the block |
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151 CYG_ASSERT( freeblocks <= numblocks, "freeblocks overflow" ); |
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152 return true; |
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153 } |
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154 |
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155 // ------------------------------------------------------------------------- |
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156 #endif // ifndef CYGONCE_KERNEL_MFIXIMPL_INL |
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157 // EOF mfiximpl.inl |
