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Text File  |  1975-07-17  |  2.4 KB  |  166 lines
  1. /    storage allocator for use with C
  2. /
  3. /
  4. /
  5. /    hand-tooled from C compilation to modify save-return
  6. /    so that it can be called from within the C save
  7. /    when running with coroutines
  8. /
  9. /#
  10. //*
  11. / *    C storage allocator
  12. / *    (circular first fit strategy)
  13. / */
  14. /#define BLOK 512
  15. /#define BUSY 01
  16. /
  17. /char *allocs[2] {        /*initial empty arena*/
  18. /    &allocs[1],
  19. /    &allocs[0]
  20. /};
  21. /struct { int word; };
  22. /char **allocp &allocs[1];    /*current search pointer*/
  23. /char **alloct &allocs[1];    /*top of arena (last cell)*/
  24. /
  25. /alloc(nbytes)
  26. /{
  27. /    register int nwords;
  28. /    register char **p, **q;
  29. /    static char **t;
  30. /
  31. /    allocs[0].word =| BUSY;    /*static initialization*/
  32. /    allocs[1].word =| BUSY;
  33. /
  34. /    nwords = (nbytes+(2*sizeof(p)-1))/sizeof(p);
  35. /    for(p=allocp;;) {
  36. /        do {
  37. /            if((p->word&BUSY)==0) {
  38. /                while(((q = *p)->word&BUSY)==0)
  39. /                    *p = *q;
  40. /                if(q >= &p[nwords])
  41. /                    goto found;
  42. /            }
  43. /            q = p;
  44. /            p = p->word & ~BUSY;
  45. /        } while(q>=allocp || p<allocp);
  46. /        if((*alloct=t=sbrk(BLOK*sizeof(p))) == -1)
  47. /            return(-1);
  48. /        if(t!=alloct+1)
  49. /            alloct->word =| BUSY;
  50. /        alloct = (*t = &t[BLOK]-1);
  51. /        *alloct = allocs;
  52. /        alloct->word =| BUSY;
  53. /    }
  54. /found:
  55. /    allocp = &p[nwords];
  56. /    if(q>allocp)
  57. /        *allocp = *p;
  58. /    *p = allocp.word|BUSY;
  59. /    return(p+1);
  60. /}
  61. /
  62. /free(p)
  63. /char **p;
  64. /{
  65. /    allocp = p-1;
  66. /    allocp->word =& ~BUSY;
  67. /}
  68. .globl    _allocs
  69. .data
  70. _allocs=.
  71. 2+_allocs
  72. _allocs
  73. .globl    _allocp
  74. .data
  75. _allocp=.
  76. 2+_allocs
  77. .globl    _alloct
  78. .data
  79. _alloct=.
  80. 2+_allocs
  81. .globl    _alloc
  82.  
  83. .globl    _sbrk
  84. .text
  85. _alloc:
  86. mov    r5,-(sp)
  87. mov    sp,r5
  88. mov    r4,-(sp)
  89. mov    r3,-(sp)
  90. mov    r2,-(sp)
  91. bis    $1,_allocs
  92. bis    $1,2+_allocs
  93. mov    4(r5),r4
  94. add    $3,r4
  95. asr    r4
  96. mov    _allocp,r3
  97. jbr    L6
  98. L7:mov    r3,r2
  99. mov    (r3),r3
  100. bic    $!177776,r3
  101. cmp    r2,_allocp
  102. jhis    L6
  103. cmp    r3,_allocp
  104. jlo    L6
  105. mov    $2000,-(sp)
  106. jsr    pc,*$_sbrk
  107. tst    (sp)+
  108. mov    r0,t
  109. mov    r0,*_alloct
  110. cmp    $177777,r0
  111. jeq    L11
  112. mov    _alloct,r0
  113. add    $2,r0
  114. cmp    t,r0
  115. jeq    L12
  116. bis    $1,*_alloct
  117. L12:mov    t,r0
  118. add    $1776,r0
  119. mov    r0,*t
  120. mov    r0,_alloct
  121. mov    $_allocs,*_alloct
  122. bis    $1,*_alloct
  123. L6:bit    $1,(r3)
  124. jeq    L8
  125. jbr    L7
  126. L20001:mov    (r2),(r3)
  127. L8:mov    (r3),r2
  128. bit    $1,(r2)
  129. jeq    L20001
  130. mov    r4,r0
  131. asl    r0
  132. add    r3,r0
  133. cmp    r2,r0
  134. jlo    L7
  135. mov    r4,r0
  136. asl    r0
  137. add    r3,r0
  138. mov    r0,_allocp
  139. cmp    r2,r0
  140. jlos    L13
  141. mov    (r3),*_allocp
  142. L13:mov    _allocp,r0
  143. bis    $1,r0
  144. mov    r0,(r3)
  145. mov    r3,r0
  146. add    $2,r0
  147. L11:
  148. mov    (sp)+,r2
  149. mov    (sp)+,r3
  150. mov    (sp)+,r4
  151. mov    (sp)+,r5
  152. rts    pc
  153. .globl    _free
  154. .text
  155. _free:
  156. mov    r5,-(sp)
  157. mov    sp,r5
  158. mov    4(r5),r0
  159. add    $177776,r0
  160. mov    r0,_allocp
  161. bic    $!177776,*_allocp
  162. mov    (sp)+,r5
  163. rts    pc
  164. .bss
  165. t:    .=.+2
  166.