The Ring programming language version 1.5.2 book - Part 74 of 181
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This document provides information about low level functions in Ring that allow interaction with C code and pointers. It describes the following functions: - callgc() forces garbage collection to free temporary variables - varptr() gets a C pointer for a Ring variable - space() allocates memory and returns a string pointer - nullpointer() returns a NULL pointer for optional parameters - object2pointer() gets a C pointer for a Ring list or object - pointer2object() converts a C pointer back to a Ring list or object - ptrcmp() compares two C pointers It also briefly mentions ringvm functions for getting information about the runtime environment like loaded classes, functions, memory usage and more.
![Ring Documentation, Release 1.5.2
65.1 callgc() function
Use this function to force calling the garbage collector during function execution when you use a loop that create temp.
variables that you don’t free using the assignment operation.
It’s very rare to need this function but it’s useful when you create something like event-loop for your game engine and
start creating lists on the fly when you call functions.
Example
While True
# process events
# call functions using temp. lists like myfunc(["temp list"])
# call the garbage collector
callgc()
End
Tip: In Ring the garbage collector works automatically in the end of function execution or when you use the assign-
ment statement.
65.2 varptr() function
Use the varptr() function when you need to pass a pointer to a C/C++ function.
Syntax:
varptr(cVariableName,cPointerType) —> Low Level Object (C Pointer)
example:
r = 10
z = 20
see r + nl
see varptr("r","int")
see varptr("z","int")
Output:
10
00E3C740
int
2
00E3BEC0
int
2
Note: the low level object is a list contains three items (The Pointer, The Type, The Status)
65.3 space() function
Use the space function to allocate a specific number of bytes in Memory.
65.1. callgc() function 712](https://image.slidesharecdn.com/731pdfsamfayedringdoc1-180228061132/85/The-Ring-programming-language-version-1-5-2-book-Part-74-of-181-8-320.jpg)
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The Ring programming language version 1.5.2 book - Part 74 of 181
- 1. Ring Documentation, Release 1.5.2 64.4 Printing Final Intermediate Code Command: ring test.ring -icfinal Output: Hello World 1 2 3 4 5 6 7 8 9 10 welcome x: 10.000000 y: 20.000000 z: 30.000000 =================================================== Byte Code - After Execution by the VM =================================================== PC OPCode Data 1 ReturnNull 2 Func main 3 NewLine 2 4 FuncExE 5 PushC Hello World 6 PushP 007D3670 0 7 PushV 8 SUM 0 9 Print 10 NewLine 3 11 ExitMark 29 28 12 LoadAFirst x 13 PushN 1.000000 14 BeforeEqual 0 15 Assignment 16 PushN 1.000000 17 StepNumber 18 JumpVarLPLENum x 10.000000 29 19 NewLine 4 20 FuncExE 21 PushPLocal x 0 22 PushV 23 PushP 007D3670 0 24 PushV 25 SUM 0 26 Print 27 NewLine 5 64.4. Printing Final Intermediate Code 705
- 2. Ring Documentation, Release 1.5.2 28 IncLPJump x 18 29 POPExitMark 30 POPStep 31 NewLine 6 32 LoadFuncP test 33 Call 0 34 NoOperation 35 NewLine 8 36 PushV 37 FreeStack 38 ReturnNull 39 Func test 40 NewLine 9 41 FuncExE 42 PushC welcome 43 PushP 007D3670 0 44 PushV 45 SUM 0 46 Print 47 NewLine 10 48 PushPLocal o1 0 49 AssignmentPointer 50 New point 51 SetScope 52 PushV 53 BraceStart 54 LoadA x 0 58 55 AssignmentPointer 56 PushN 10.000000 57 BeforeEqual 0 58 SetProperty 0 106 59 FreeStack 60 LoadA y 0 64 61 AssignmentPointer 62 PushN 20.000000 63 BeforeEqual 0 64 SetProperty 0 141 65 FreeStack 66 LoadA z 0 70 67 AssignmentPointer 68 PushN 30.000000 69 BeforeEqual 0 70 SetProperty 0 176 71 FreeStack 72 LoadFunc ismethod 73 LoadA self 0 74 PushV 75 PushC braceend 76 Call 77 NoOperation 78 PushV 79 JumpZ 85 80 LoadFunc braceend 81 Call 82 NoOperation 83 PushV 84 FreeStack 85 BraceEnd 64.4. Printing Final Intermediate Code 706
- 3. Ring Documentation, Release 1.5.2 86 FreeStack 87 NewLine 11 88 FuncExE 89 PushPLocal o1 0 90 PushV 91 Print 92 NewLine 13 93 ReturnNull 94 Class point 007D8470 95 NewLabel 96 LoadA x 0 97 PushV 98 FreeStack 99 LoadA y 0 100 PushV 101 FreeStack 102 LoadA z 0 103 PushV 104 FreeStack 105 ReturnNull 106 LoadFunc ismethod 107 LoadA ring_gettemp_var 0 108 PushV 109 PushC setx 110 Call 0 111 NoOperation 112 PushV 113 JumpZ 132 114 NewLine 2 115 LoadA ring_gettemp_var 0 116 LoadMethod setx 117 LoadA ring_settemp_var 0 118 PushV 119 Call 0 1 120 AfterCallMethod 121 PushV 122 FreeStack 123 NewLine 3 124 LoadA ring_tempflag_var 0 128 125 AssignmentPointer 126 PushN 0.000000 127 BeforeEqual 0 128 Assignment 0 0 129 FreeStack 130 NewLine 4 131 Jump 140 132 NewLine 5 133 PushP 007D37D8 0 137 134 AssignmentPointer 135 PushN 1.000000 136 BeforeEqual 0 137 Assignment 0 0 138 FreeStack 139 NewLine 6 140 Return 141 LoadFunc ismethod 142 LoadA ring_gettemp_var 0 143 PushV 64.4. Printing Final Intermediate Code 707
- 4. Ring Documentation, Release 1.5.2 144 PushC sety 145 Call 0 146 NoOperation 147 PushV 148 JumpZ 167 149 NewLine 2 150 LoadA ring_gettemp_var 0 151 LoadMethod sety 152 LoadA ring_settemp_var 0 153 PushV 154 Call 0 1 155 AfterCallMethod 156 PushV 157 FreeStack 158 NewLine 3 159 LoadA ring_tempflag_var 0 163 160 AssignmentPointer 161 PushN 0.000000 162 BeforeEqual 0 163 Assignment 0 0 164 FreeStack 165 NewLine 4 166 Jump 175 167 NewLine 5 168 PushP 007D37D8 0 172 169 AssignmentPointer 170 PushN 1.000000 171 BeforeEqual 0 172 Assignment 0 0 173 FreeStack 174 NewLine 6 175 Return 176 LoadFunc ismethod 177 LoadA ring_gettemp_var 0 178 PushV 179 PushC setz 180 Call 0 181 NoOperation 182 PushV 183 JumpZ 202 184 NewLine 2 185 LoadA ring_gettemp_var 0 186 LoadMethod setz 187 LoadA ring_settemp_var 0 188 PushV 189 Call 0 1 190 AfterCallMethod 191 PushV 192 FreeStack 193 NewLine 3 194 LoadA ring_tempflag_var 0 198 195 AssignmentPointer 196 PushN 0.000000 197 BeforeEqual 0 198 Assignment 0 0 199 FreeStack 200 NewLine 4 201 Jump 210 64.4. Printing Final Intermediate Code 708
- 5. Ring Documentation, Release 1.5.2 202 NewLine 5 203 PushP 007D37D8 0 207 204 AssignmentPointer 205 PushN 1.000000 206 BeforeEqual 0 207 Assignment 0 0 208 FreeStack 209 NewLine 6 210 Return =================================================== 64.5 CGI Support Command: ring test.ring -cgi 64.6 No Run Command: ring test.ring -norun 64.7 Printing Instruction Operation Code Command: ring test.ring -ins Output: =================================================== Operation : ReturnNull PC : 1 Line Number : 1 , File test.ring SP (After) : 0 - FuncSP : 0 LineNumber 1 =================================================== ..... ..... ..... Tip: Output removed from the previous example because it’s very large! 64.8 Performance Command: 64.5. CGI Support 709
- 6. Ring Documentation, Release 1.5.2 ring test.ring -performance Output: =================================================== Date : 2015/09/15 Time : 15:56:17 Clock : 0 =================================================== Hello World 1 2 3 4 5 6 7 8 9 10 welcome x: 10.000000 y: 20.000000 z: 30.000000 =================================================== Date : 2015/09/15 Time : 15:56:17 Clock : 0 =================================================== 64.9 Generate Object File You can generate object file (.ringo) from your source code file (.ring) using -go option Tip: You will get one object file to use for distributing/running your application which may contains one or many ring source files that you can keep or distribute based on the application (commercial or open source). Command: ring test.ring -go To run the compiled object file ring test.ringo 64.9. Generate Object File 710
- 7. CHAPTER SIXTYFIVE LOW LEVEL FUNCTIONS In this chapter we will learn about the low level functions provided by Ring • callgc() • varptr() • space() • nullpointer() • object2pointer() • pointer2object() • ptrcmp() • ringvm_cfunctionslist() • ringvm_functionslist() • ringvm_classeslist() • ringvm_packageslist() • ringvm_memorylist() • ringvm_calllist() • ringvm_fileslist() • ringvm_settrace() • ringvm_tracedata() • ringvm_traceevent() • ringvm_tracefunc() • ringvm_scopescount() • ringvm_evalinscope() • ringvm_passerror() • ringvm_hideerrorMsg() • ringvm_callfunc() 711
- 8. Ring Documentation, Release 1.5.2 65.1 callgc() function Use this function to force calling the garbage collector during function execution when you use a loop that create temp. variables that you don’t free using the assignment operation. It’s very rare to need this function but it’s useful when you create something like event-loop for your game engine and start creating lists on the fly when you call functions. Example While True # process events # call functions using temp. lists like myfunc(["temp list"]) # call the garbage collector callgc() End Tip: In Ring the garbage collector works automatically in the end of function execution or when you use the assign- ment statement. 65.2 varptr() function Use the varptr() function when you need to pass a pointer to a C/C++ function. Syntax: varptr(cVariableName,cPointerType) —> Low Level Object (C Pointer) example: r = 10 z = 20 see r + nl see varptr("r","int") see varptr("z","int") Output: 10 00E3C740 int 2 00E3BEC0 int 2 Note: the low level object is a list contains three items (The Pointer, The Type, The Status) 65.3 space() function Use the space function to allocate a specific number of bytes in Memory. 65.1. callgc() function 712
- 9. Ring Documentation, Release 1.5.2 Syntax: Space(nBytesCount) ---> String Example: mystring = space(200) See "String Size : " + len(mystring) + nl See "String : " + mystring + nl See "String Pointer : " See varptr("mystring","char *") Output: String Size : 200 String : String Pointer : 00FF8FE8 char * 2 Note: You may need the space() and VarPtr() functions to pass buffers to C functions. 65.4 nullpointer() function You may need to pass the NULL pointer to a C function that may expect a pointer as parameter and accept NULL pointers for optional parameters. Example: The next example uses the SDL_BlitSurface() function from the LibSDL Library through RingSDL The function accept SDL_Rect pointers in the second and the last parameter. Also the function accept NULL pointers, so we can pass them using the NULLPointer() Function. SDL_BlitSurface(text, nullpointer(), surface, nullpointer()) Note: The previous code doesn’t work alone, you need to learn how to use RingSDL first. Tip: We can pass NULL as parameter instead of using NULLPointer() 65.5 object2pointer() function Use this function to get a C pointer for Ring lists and objects Syntax: object2pointer(List|Object) --> Low Level Object ( C Pointer ) 65.6 pointer2object() function Use this function to get the Ring list and/or object from the low level object (C Pointer) 65.4. nullpointer() function 713
- 10. Ring Documentation, Release 1.5.2 Syntax: pointer2object(Low Level Object) ---> List|Object Example: # Create the list mylist = 1:5 # Create pointer to the list x = object2pointer(mylist) see x see nl # Add items to the list mylist + "welcome" # print the list items y = pointer2object(x) see y Output: 0069A5D8 OBJECTPOINTER 0 1 2 3 4 5 welcome Note: In Ring the assignment operator copy lists and objects by value, to copy by reference Just use the ob- ject2pointer() and pointer2object() functions. Tip: The object2pointer() and pointer2object() are used in the stdlib - Tree Class implementation to create a reference for the parent node (object) in the child node (another object). 65.7 ptrcmp() function We can compare between two pointers (C Objects) using the ptrcmp() function. Syntax: ptrcmp(oObject1,oObject2) ---> value = 1 if oObject1 = oObject2 value = 0 if oObject1 != oObject2 Example: fp = fopen("ptrcmp.ring","r") fp2 = fp fp3 = fopen("ptrcmp.ring","r") 65.7. ptrcmp() function 714