SIC Simulator實作

# SIC Simulator實作因系統程式的需求，使用C語言實作SIC Simulator ## 初始值、變數宣告 ### 檔案、輸入宣告 ``` FILE* f; //filename char fname[20]; // char tname[20]; //command line char c_line[30]; //object code line char o_line[80]; // command load,show,unload,exit,run char cmd[8]; //program length int prog_len = 0; //start address int start_add = 0; //record first address int first_add = 0; //cursor address int curr_add = 0; ``` ### load、run部分宣告 ``` //virtual memory block char* memory; int mem_size = 0; int loaded = 0; int op = 0; int indexed = 0; int operand = 0; int running = 0; //register A,register X,register L,reister PC,register SW int reg_A, reg_X, reg_L, reg_PC, reg_SW; const char s_command[5][7] = { "load", "show", "unload", "exit", "run" }; const int MAXADD = 0x7FFF; const int IKEY = 0x8000; const char optab[26][3] = { "18", "40", "28", "24", "3C", "30", "34", "38", "48", "00", "50", "08", "04", "20", "44", "D8", "4C", "0C", "54", "14", "E8", "10", "1C", "E0", "2C", "DC" }; ``` 除了SIC指令在初始實都先給上數字之外，還設定SW的值，**未設定** = 0、**相等(eq)** = 1、**大於(gt)** = 2及**小於(lt)** = 3。 ## Load ### Read Header Record ``` void rd_header() { char tmp[7]; int i, j, s; for (i = 7, j = 0; i < 13; i++, j++) tmp[j] = o_line[i]; tmp[j] = '\0'; sscanf(tmp, "%x", &start_add); for (i = 13, j = 0; i < 19; i++, j++) tmp[j] = o_line[i]; tmp[j] = '\0'; sscanf(tmp, "%x", &prog_len); s = prog_len * 2 + 1; memory = (char*)malloc(sizeof(char) * s); if (memory) { for (i = 0; i < s; i++) memory[i] = 'X'; memory[s - 1] = '\0'; loaded = 1; mem_size = s; } else { printf("Loading Failed! (Memory allocation error)\n"); } } ``` ### Read Text Record ``` void rd_text() { char tmp[7]; int i, j, l, s; for (i = 1, j = 0; i < 7; i++, j++) tmp[j] = o_line[i]; tmp[j] = '\0'; sscanf(tmp, "%x", &s); //printf("%X",s); for (i = 7, j = 0; i < 9; i++, j++) tmp[j] = o_line[i]; tmp[j] = '\0'; sscanf(tmp, "%x", &l); l = 9 + l * 2; for (i = 9, j = (s - start_add) * 2; i < l; i++, j++) memory[j] = o_line[i]; } ``` ### Read End Record ``` void rd_end() { char tmp[7]; int i, j; for (i = 1, j = 0; i < 7; i++, j++) tmp[j] = o_line[i]; tmp[j] = '\0'; sscanf(tmp, "%x", &first_add); } ``` 這部分的程式碼為老師提供範例碼就有提供，就仔細看過理解後用於load的操作上，在讀record的部分本來就有完成**Relocation**的部分，因此在Absolute Loader的演算法上，很多部分已經在讀Record時完成，也算是一個很大的幫助。接下來就是將剩下的部分依照演算法完成。 ### Load ``` void s_load() { int i; if(loaded) printf("ERROR : There is already an object program loaded in memory !\n"); else{ printf(" file name > "); fgets(fname, 20, stdin); i = strlen(fname); fname[i - 1] = '\0'; f = fopen(fname, "r"); if(f == NULL) printf("ERROR : Failed to open dile!\n"); else{ fgets(o_line, 80, f); i = strlen(o_line); o_line[i - 1] = '\0'; char prog_name[7]; if (o_line[0] == 'H') { int i, j; for (i = 1, j = 0; i < 7; i++, j++) prog_name[j] = o_line[i]; prog_name[j] = '\0'; rd_header(); } fgets(o_line, 80, f); //verify program name and length printf("Program name = [%s], Program Length = [%x]\n", prog_name, prog_len); while (o_line[0] != 'E') { int i; i = strlen(o_line); o_line[i - 1] = '\0'; //printf("%s\n", o_line); rd_text(); fgets(o_line, 80, f); } rd_end(); loaded = 1; o_line[0] = '\0'; printf("Load Successful!\n"); } fclose(f); } } ``` 看到其他人的程式碼都是將開檔案部分直接就寫在load的command之後，但是由於當初所想就沒想那麼多，就在load的部分上加上一個輸入的部分。 **loaded**用於紀錄是否已經有程式在內部，如果已經有城市在內部就沒有辦法load並且回報錯誤資訊。由於每個Record的第一個字元會提示這個Record是哪種Record，可用於判斷是否將程式讀完，並且在讀完程式時回報Load Successful!。這個部份在課本上有提供演算法，就在這邊也順便附上。 ![](https://i.imgur.com/IZn3RFl.png) 其實簡單來說就是把每個Record讀完之後跳到結束位址。 ## Show ``` void s_show() { int i, j = 0; for(curr_add = first_add;curr_add < first_add + prog_len;curr_add += 16){ printf("%x ",curr_add); for(i = 0 + j * 32;i < 8 + j * 32 && memory[i] != '\0';i++) printf("%c",memory[i]); printf(" "); for(;i < 16 + j * 32 && memory[i] != '\0';i++) printf("%c",memory[i]); printf(" "); for(;i < 24 + j * 32 && memory[i] != '\0';i++) printf("%c",memory[i]); printf(" "); for(;i < 32 + j * 32 && memory[i] != '\0';i++) printf("%c",memory[i]); printf("\n"); j++; } } ``` 顯示目前Memory內所包含的資料，由於前便是使用Dynamic Allocated來進行陣列配置，因此會依照程式的大小配置陣列大小。在未配置的空間會以'X'裝入。 ## Unload 主要目的就是將已經讀入的部分清除。 ``` void s_unload() { if(loaded){ fclose(f); fname[0] = '\0'; o_line[0] = '\0'; free(memory); prog_len = 0; start_add = 0; first_add = 0; curr_add = 0; mem_size = 0; loaded = 0; op = 0; indexed = 0; operand = 0; } } ``` 這部分主要就是將已經讀入的東西清除，因此這部分就十分直覺。 ## Run ### initial_run ``` void init_run() { reg_A = 0; reg_X = 0; reg_L = 0; reg_PC = first_add; reg_SW = 0; curr_add = (first_add - start_add) * 2; running = 1; } ``` 初始執行前的狀態，將暫存器歸零，Program Counter調到目前即將執行的位址。 ### get_op ``` void get_op() { char s[3]; char t[5]; s[0] = memory[curr_add]; s[1] = memory[curr_add + 1]; s[2] = '\0'; op = lookup(s); t[0] = memory[curr_add + 2]; t[1] = memory[curr_add + 3]; t[2] = memory[curr_add + 4]; t[3] = memory[curr_add + 5]; t[4] = '\0'; sscanf(t, "%X", &operand); if (operand >= IKEY) { indexed = 1; operand -= IKEY; } else { indexed = 0; } curr_add += 6; //printf("*%X*", curr_add ); reg_PC += 3; } ``` 針對每一個object code進行分析，將opode讀出，operand讀出，並進行轉換。由於前面有對每一個opcode進行數字編號，這個部分主要就是轉換，並且進行位置的調控。 ### get_value ``` int get_value(int r, int x) { int tmp = 0; char s[7]; int i, j; if (x) r += reg_X; i = (r - start_add) * 2; for (j = 0; j < 6; j++) s[j] = memory[i++]; s[6] = '\0'; sscanf(s, "%X", &tmp); return tmp; } ``` ### get_byte ``` int get_byte(int r, int x) { int tmp = 0; char s[3]; int i, j; if (x) r += reg_X; i = (r - start_add) * 2; j = 0; s[j++] = memory[i++]; s[j++] = memory[i++]; s[2] = '\0'; sscanf(s, "%X", &tmp); printf("LDCH: r = [%X], x = [%d], tmp = [%c]\n", r, x, tmp); return tmp; } ``` ### put_byte ``` void put_byte(int k, int r, int x) { int tmp = 0; char s[3]; int i, j; if (x) r += reg_X; sprintf(s, "%02X", k); i = (r - start_add) * 2; j = 0; memory[i++] = s[j++];; memory[i++] = s[j++];; } ``` ### pute_value ``` void put_value(int k, int r, int x) { int tmp = 0; char s[7]; int i, j; printf("put_value ( %X, %X, %X ) starts.\n", k, r, x); if (x) r += reg_X; sprintf(s, "%06X", k); i = (r - start_add) * 2; for (j = 0; j < 6; j++) memory[i++] = s[j]; printf("put_value ( %X, %X, %X ) finishes.\n", k, r, x); } ``` 在進行LD及ST暫存器時會使用到，並且在進行PC relative的指令取值時也會使用到。 ### show_reg ``` void show_reg() { printf("Register A = [%06X];\n", reg_A); printf("Register X = [%06X];\n", reg_X); printf("Register L = [%06X];\n", reg_L); printf("Register SW = [%06X];\n", reg_SW); printf("Register PC = [%06X];\n", reg_PC); } ``` 展示目前reg的狀況，用於執行完後展示。 ### s_run ``` void s_run() { init_run(); printf("*%X*", curr_add ); while (running) { get_op(); //printf("%X", operand ); //printf("%d\n", op); switch(op){ case 0: reg_A += get_value(operand,indexed); break; case 1: reg_A &= get_value(operand,indexed); break; case 2: if(reg_A > get_value(operand,indexed)) reg_SW = gt; else if(reg_A < get_value(operand,indexed)) reg_SW = lt; else reg_SW = eq; break; case 3: reg_A /= get_value(operand,indexed); break; case 4: reg_PC = operand; curr_add = (reg_PC - start_add)*2; break; case 5: if(reg_SW == eq) reg_PC = operand,curr_add = (reg_PC - start_add)*2; break; ``` ``` case 6: if(reg_SW == gt) reg_PC = operand,curr_add = (reg_PC - start_add)*2; break; case 7: if(reg_SW == lt) reg_PC = operand,curr_add = (reg_PC - start_add)*2; break; ``` ``` case 8: reg_L = reg_PC,reg_PC = operand, curr_add = (reg_PC - start_add)*2; break; case 9: reg_A = get_value(operand,indexed); break; case 10: reg_A = (reg_A & 16776960) | get_byte(operand,indexed); break; ``` case 11: reg_L = get_value(operand,indexed); break; case 12: reg_X = get_value(operand,indexed); case 13: reg_A *= get_value(operand,indexed); break; case 14: reg_A |= get_value(operand,indexed); break; case 15: reg_A = reg_A; break; ``` case 16: if(reg_L == 0) running = 0; else reg_PC = reg_L,curr_add = (reg_PC - start_add) * 2; break; case 17: put_value(reg_A,operand,indexed); break; case 18: put_byte(reg_A,operand,indexed); break; case 19: put_value(reg_L,operand,indexed); break; case 20 : put_value(reg_SW,operand,indexed); break; ``` ``` case 21: put_value(reg_X,operand,indexed); break; case 22: reg_A -= get_value(operand,indexed); break; case 23: reg_SW = gt; break; case 24: reg_X += 1; if(reg_X > get_value(operand,indexed)) reg_SW = gt; else if(reg_X < get_value(operand,indexed)) reg_SW = lt; else reg_SW = eq; break; case 25: reg_A = reg_A; break; default: break; } } show_reg(); } ``` 進行程式碼的執行，這個部分可以參考[SIC指令集](http://solomon.ipv6.club.tw/Course/SP.941/sic-instruction.html)來進行，由於程式碼較多就不一一解釋，大部分的函式都可以從前面的介紹中找到，比較特別的部分是在測試Device的部分，由於無法真正進行，只有進行準備或者跳過。 ## 主程式 ``` int main() { int comm = 0; comm = readline(); while (comm != cEXIT) { switch (comm) { case cLOAD: s_load(); break; case cSHOW: s_show(); break; case cUNLOAD: s_unload(); break; case cRUN: s_run(); break; default: printf("Unknown Command!\n"); break; } comm = cMIN; comm = readline(); } if (loaded) s_unload(); } ``` 當輸入exit時會結束程式並進行歸零，其餘就按照上面指令碼名稱去呼叫函式。至此，SIC Simulator的介紹及實作也告一個段落。 ## Sample Run ![](https://i.imgur.com/4UQg7Gp.png) ![](https://i.imgur.com/sE5tLVH.png) ![](https://i.imgur.com/c0Ci3Vr.png) 此為將程式碼在精簡後的結果(將一些檢查部分去除)

Syntax	Example	Reference
# Header	Header	基本排版
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1. Ordered List	Ordered List
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`Code`	`Code`	在筆記中貼入程式碼
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