libgo/runtime/go-make-slice.c

   1 /* go-make-slice.c -- make a slice.
   2
   3    Copyright 2011 The Go Authors. All rights reserved.
   4    Use of this source code is governed by a BSD-style
   5    license that can be found in the LICENSE file.  */
   6
   7 #include <stdint.h>
   8
   9 #include "runtime.h"
  10 #include "go-alloc.h"
  11 #include "go-assert.h"
  12 #include "go-panic.h"
  13 #include "go-type.h"
  14 #include "array.h"
  15 #include "arch.h"
  16 #include "malloc.h"
  17
  18 /* Dummy word to use as base pointer for make([]T, 0).
  19    Since you cannot take the address of such a slice,
  20    you can't tell that they all have the same base pointer.  */
  21 uintptr runtime_zerobase;
  22
  23 struct __go_open_array
  24 __go_make_slice2 (const struct __go_type_descriptor *td, uintptr_t len,
  25                   uintptr_t cap)
  26 {
  27   const struct __go_slice_type* std;
  28   intgo ilen;
  29   intgo icap;
  30   uintptr_t size;
  31   struct __go_open_array ret;
  32
  33   __go_assert (td->__code == GO_SLICE);
  34   std = (const struct __go_slice_type *) td;
  35
  36   ilen = (intgo) len;
  37   if (ilen < 0
  38       || (uintptr_t) ilen != len
  39       || (std->__element_type->__size > 0
  40           && len > MaxMem / std->__element_type->__size))
  41     runtime_panicstring ("makeslice: len out of range");
  42
  43   icap = (intgo) cap;
  44   if (cap < len
  45       || (uintptr_t) icap != cap
  46       || (std->__element_type->__size > 0
  47           && cap > MaxMem / std->__element_type->__size))
  48     runtime_panicstring ("makeslice: cap out of range");
  49
  50   ret.__count = ilen;
  51   ret.__capacity = icap;
  52
  53   size = cap * std->__element_type->__size;
  54
  55   if (size == 0)
  56     ret.__values = &runtime_zerobase;
  57   else if ((std->__element_type->__code & GO_NO_POINTERS) != 0)
  58     ret.__values = runtime_mallocgc (size, FlagNoPointers, 1, 1);
  59   else
  60     {
  61       ret.__values = runtime_mallocgc (size, 0, 1, 1);
  62
  63       if (UseSpanType)
  64         runtime_settype (ret.__values,
  65                          (uintptr) std->__element_type | TypeInfo_Array);
  66     }
  67
  68   return ret;
  69 }
  70
  71 struct __go_open_array
  72 __go_make_slice1 (const struct __go_type_descriptor *td, uintptr_t len)
  73 {
  74   return __go_make_slice2 (td, len, len);
  75 }
  76
  77 struct __go_open_array
  78 __go_make_slice2_big (const struct __go_type_descriptor *td, uint64_t len,
  79                       uint64_t cap)
  80 {
  81   uintptr_t slen;
  82   uintptr_t scap;
  83
  84   slen = (uintptr_t) len;
  85   if ((uint64_t) slen != len)
  86     runtime_panicstring ("makeslice: len out of range");
  87
  88   scap = (uintptr_t) cap;
  89   if ((uint64_t) scap != cap)
  90     runtime_panicstring ("makeslice: cap out of range");
  91
  92   return __go_make_slice2 (td, slen, scap);
  93 }
  94
  95 struct __go_open_array
  96 __go_make_slice1_big (const struct __go_type_descriptor *td, uint64_t len)
  97 {
  98   return __go_make_slice2_big (td, len, len);
  99 }