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1 C with Continuation (CwC) and Continuation based C (CbC)
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2
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3 Shinji Kono
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4 University of the Ryukyus
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5
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6 0. What is this.
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7
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8 We have gcc and LLVM version. You should use these.
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9
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10 This is a extension of C ( and a subset of C ). It has a
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11 programming unit which is called code segment. Code
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12 segment can be communicate with so called light weight continuation.
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13
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14
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15 #include <stdio.h>
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16
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17 code factorial(int n,int result,int orig,
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18 code(*print)(),code(*exit1)(), void *exit1env)
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19 {
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20 if (n<0) {
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21 printf("err %d!\n",n);
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22 goto (*exit1)(0),exit1env;
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23 }
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24 if (n==0)
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25 goto (*print)(n,result,orig,print,exit1,exit1env);
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26 else {
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27 result *= n;
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28 n--;
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29 goto factorial(n,result,orig,print,exit1,exit1env);
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30 }
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31 }
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32
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33 int main( int ac, char *av[])
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34 {
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35 int n;
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36 n = 10;
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37 goto factorial(n,1,n,print,return,environment);
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38 }
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39
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40 code print(int n,int result,int orig,code(*print)(),(*exit1)(),void*exit1env)
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41 {
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42 printf("%d! = %d\n",orig, result);
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43 goto (*exit1)(0),exit1env;
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44 }
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45
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46 If you don't use function call, this language becomes subset of C.
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47 It is called Continuation based C. Actually it can be a lower layer of
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48 C language. Normal C program can be compiled into CbC.
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49
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50 CbC is a kind of architecture independent assembler language.
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51
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52 1. Syntax
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53
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54 code code_segment_name(interfaces) {
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55 body;
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56 }
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57
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58 code is a type for code segment. A code segment has no return
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59 statements.
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60
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61 Interfaces are arguments. It can be struts. or unions. Some
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62 part of interfaces are mapped into registers. No
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63 references are allowed in register interface variables.
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64
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65 Goto statements transfer the control from a segment
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66 to a segment.
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67 goto segment_name(interfaces);
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68 If two code segments has a same interfaces, transfer cost is very
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69 small. It us usually a single jump instruction.
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70 If there are differences, some parallel assignment is performed.
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71
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72 2. Interaction between function and code segment.
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73
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74 In CwC, you can call C function at any time in code segments.
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75 If you want to call code segment from C and want to do some
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76 return, explicit handling of function environment.
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77
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78 goto factorial(n,1,n,print,return,environment);
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79
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80 return and environment is a special variable which contains
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81 return point. An environment variable is something like jumpbuf
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82 in setjump, but it is a simple pointer. Unlike jumpbuf,
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83 there is no way to allocate are for environment.
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84 void *environment;
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85
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86 A return variable is a continuation with environment of
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87 original function. It's type is varied for called function.
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88
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89 code (*return)(int return_value);
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90
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91 To go to the continuation, use goto with environment.
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92
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93 goto (*exit1)(0),exit1env;
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94
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95 3. How to use
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96
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97 mc-powerpc, mc-ia32 is a compiler. It generates assembler
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98 source code .s from C source code.
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99
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100 mc-powerpc source.c
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101 gcc source.s
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102 generates a.out.
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103 mc-powerpc source.c
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104 gcc -c sources.s
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105 generates sources.o
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106
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107 -s comments in assembler source.
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108 -c check only.
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109 -v report memory usage
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110 -oname output file names
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111 -Dname define name
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112 -Dname=value define name as value
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113 '-Dname(a)=a+1' define macro function with args
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114 -Idir/ add library include directory. / is necessary.
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115
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116 Some examples can be fond in test directory.
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117
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118 3. Unimplemented lists
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119
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120 Mips version is not ready.
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121
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122 64bit long long is now supported
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123 // long long, long double, unsigned long long can be used as type,
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124 // but no operation (including assignment) are no allowed.
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125 // Long long value (0LL) can be used but it gives long value.
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126 // Long is equal to an int and a pointer (32bit).
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127
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128 Only Mac OS X and Red hat Linux is supported.
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129 Intel Mac is supported.
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130
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131 Inline directive is ignored and gives normal function definition.
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132
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133 Register float is supported in Power PC
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134 // Register float arguments does no accepts assignment operation such as
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135 // *=, /=, +=.
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136
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137 //No built-in alloca.
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138
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139 // No varargs.
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140
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141 Use stdarg
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142
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143 // Switch statements is implemented as series of compare and branch,
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144 // no tables.
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145
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146 // Some operations such as concatenation are not implemented in macro
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147 // processor.
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148
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149 Macro processor is a coroutine in this compiler, slightly different
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150 from cpp.
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151
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152 No -g support.
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153
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154 No runtime driver for CbC.
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155
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156 // #include does not search, sources current directory.
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157 #include does search, sources current directory.
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159 bit-field is supported, but no global initialization of bit-field.
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161
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162 /************************************************************************
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163 ** Copyright (C) 2006 Shinji Kono
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164 ** 連絡先： 琉球大学情報工学科 河野 真治
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165 ** （E-Mail Address: kono@ie.u-ryukyu.ac.jp）
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166 **
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167 ** このソースのいかなる複写，改変，修正も許諾します。ただし、
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168 ** その際には、誰が貢献したを示すこの部分を残すこと。
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169 ** 再配布や雑誌の付録などの問い合わせも必要ありません。
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170 ** 営利利用も上記に反しない範囲で許可します。
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171 ** バイナリの配布の際にはversion messageを保存することを条件とします。
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172 ** このプログラムについては特に何の保証もしない、悪しからず。
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173 **
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174 ** Everyone is permitted to do anything on this program
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175 ** including copying, modifying, improving,
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176 ** as long as you don't try to pretend that you wrote it.
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177 ** i.e., the above copyright notice has to appear in all copies.
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178 ** Binary distribution requires original version messages.
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179 ** You don't have to ask before copying, redistribution or publishing.
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180 ** THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE.
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181 ***********************************************************************/
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