1 // 2 // Illustrate allocating some unused registers as local variables of function 3 // 4 // 5 // 6 7 /* -------------------------------------------------- 8 Define required labels for EGTAPI 9 -------------------------------------------------- */ 10 .global main, Stop, CodeEnd, DataStart, DataEnd 11 12 .global Pause, sumRange 13 14 /* -------------------------------------------------- 15 Begin of the program instructions 16 -------------------------------------------------- */ 17 .text 18 main: 19 // sum = sumRange(A, x, y) 20 21 // pass A in r0 22 0000 000000E3 movw r0, #:lower16:A 23 0004 000040E3 movt r0, #:upper16:A 24 25 // pass x in r1 26 0008 001000E3 movw r1, #:lower16:x 27 000c 001040E3 movt r1, #:upper16:x 28 0010 001091E5 ldr r1, [r1] 29 30 // pass y in r2 31 0014 002000E3 movw r2, #:lower16:y 32 0018 002040E3 movt r2, #:upper16:y 33 001c 002092E5 ldr r2, [r2] 34 35 0020 FEFFFFEB bl sumRange 36 37 0024 001000E3 movw r1, #:lower16:sum 38 0028 001040E3 movt r1, #:upper16:sum 39 002c 000081E5 str r0, [r1] 40 41 Pause: 42 // sum = sumRange(B, 3, 7) 43 44 0030 000000E3 movw r0, #:lower16:B 45 0034 000040E3 movt r0, #:upper16:B 46 47 0038 0310A0E3 mov r1, #3 48 003c 0720A0E3 mov r2, #7 49 50 0040 FEFFFFEB bl sumRange 51 52 0044 001000E3 movw r1, #:lower16:sum 53 0048 001040E3 movt r1, #:upper16:sum 54 004c 000081E5 str r0, [r1] 55 56 57 58 59 Stop: 60 0050 0000A0E1 nop // Stop point of main( ) 61 62 63 sumRange: 64 // A=r0, a=r1, b=r2, i=r3, s=r4 65 66 0054 0040A0E3 mov r4, #0 // s = 0 67 0058 0130A0E1 mov r3, r1 // i = a 68 69 while: 70 005c 020053E1 cmp r3, r2 71 0060 050000AA bge whileEnd 72 73 0064 035083E0 add r5, r3, r3 // r5 = 2*i 74 0068 055085E0 add r5, r5, r5 // r5 = 4*i 75 76 006c 055090E7 ldr r5, [r0, r5] // r5 = A[i] 77 78 0070 054084E0 add r4, r4, r5 // s = s + A[i] 79 80 0074 013083E2 add r3, r3, #1 // i++ 81 0078 F7FFFFEA b while 82 83 whileEnd: 84 // return(s) 85 86 007c 0400A0E1 mov r0, r4 87 0080 0EF0A0E1 mov pc, lr 88 89 CodeEnd: 90 0084 0000A0E1 nop 91 92 /* -------------------------------------------------- 93 Begin of the permanent program variables 94 -------------------------------------------------- */ 95 .data 96 DataStart: 97 98 0000 0B000000 A: .4byte 11, 12, 13, 14, 15, 16, 17, 18, 19 , 20 98 0C000000 98 0D000000 98 0E000000 98 0F000000 99 0028 01000000 B: .4byte 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 99 02000000 99 03000000 99 04000000 99 05000000 100 0050 01000000 x: .4byte 1 101 0054 03000000 y: .4byte 3 102 0058 FFFFFFFF sum: .4byte -1 103 104 DataEnd: 105 106 .end DEFINED SYMBOLS /home/cs255001/cs255/demo/8-sub/reg-local1.s:18 .text:0000000000000000 main /home/cs255001/cs255/demo/8-sub/reg-local1.s:59 .text:0000000000000050 Stop /home/cs255001/cs255/demo/8-sub/reg-local1.s:89 .text:0000000000000084 CodeEnd /home/cs255001/cs255/demo/8-sub/reg-local1.s:96 .data:0000000000000000 DataStart /home/cs255001/cs255/demo/8-sub/reg-local1.s:104 .data:000000000000005c DataEnd /home/cs255001/cs255/demo/8-sub/reg-local1.s:41 .text:0000000000000030 Pause /home/cs255001/cs255/demo/8-sub/reg-local1.s:63 .text:0000000000000054 sumRange /home/cs255001/cs255/demo/8-sub/reg-local1.s:98 .data:0000000000000000 A /home/cs255001/cs255/demo/8-sub/reg-local1.s:22 .text:0000000000000000 $a /home/cs255001/cs255/demo/8-sub/reg-local1.s:100 .data:0000000000000050 x /home/cs255001/cs255/demo/8-sub/reg-local1.s:101 .data:0000000000000054 y /home/cs255001/cs255/demo/8-sub/reg-local1.s:102 .data:0000000000000058 sum /home/cs255001/cs255/demo/8-sub/reg-local1.s:99 .data:0000000000000028 B /home/cs255001/cs255/demo/8-sub/reg-local1.s:69 .text:000000000000005c while /home/cs255001/cs255/demo/8-sub/reg-local1.s:83 .text:000000000000007c whileEnd NO UNDEFINED SYMBOLS 1 2 .global malloc, print 3 .global stdout_start, stdout_end 4 5 // ********************************************** 6 // malloc: simulate memory allocate 7 // 8 // This function will NOT change ANY registers 9 // (I.e.: will preserve ALL registers) 10 // ********************************************** 11 malloc: 12 0000 0E002DE9 push {r1, r2, r3} // Save scratch registers 13 14 0004 001000E3 movw r1, #:lower16:maddr 15 0008 001040E3 movt r1, #:upper16:maddr // r1 = &maddr 16 000c 003091E5 ldr r3, [r1] // r3 = maddr 17 18 // -------------------------------------- 19 // Make new maddr (divisible by 8) 20 // -------------------------------------- 21 22 0010 002083E0 add r2, r3, r0 // New maddr 23 0014 082082E2 add r2, r2, #8 // Making sure it increase 24 25 0018 0700A0E3 mov r0, #0x7 // r0 = 0000..00111 26 001c 0000E0E1 mvn r0, r0 // r0 = 1111..11000 27 0020 002002E0 and r2, r2, r0 // Knock off the last 3 bits 28 0024 002081E5 str r2, [r1] // Update maddr 29 30 31 // -------------------------------------- 32 // Return to caller 33 // -------------------------------------- 34 0028 0300A0E1 mov r0, r3 // Return maddr value in r0 35 002c 0E00BDE8 pop {r1, r2, r3} // Restore scratch registers 36 0030 0EF0A0E1 mov pc, lr // Return 37 38 0034 00000400 maddr: .word 0x40000 // Start address of the heap 39 40 41 // ******************************************************************* 42 // print: simulate print output in Egtapi 43 // 44 // input: r0 = address of string 45 // r1 = # characters to write 46 // 47 // Egtapi will show ASCII data stored starting at stdout_start 48 // until stdout_end in its output area 49 // 50 // This function will NOT change ANY registers 51 // (I.e.: will preserve ALL registers) 52 // ******************************************************************* 53 print: 54 0038 1C002DE9 push {r2, r3, r4} // Save scratch registers 55 56 003c 002000E3 movw r2, #:lower16:stdout_end 57 0040 002040E3 movt r2, #:upper16:stdout_end // r2 = &stdout_end 58 0044 002092E5 ldr r2, [r2] // r2 = stdout_end 59 60 0048 0130A0E1 mov r3, r1 // r3 = # char to copy 61 62 printLoop: 63 004c 000053E3 cmp r3, #0 64 0050 0500000A beq printDone 65 66 0054 0040D0E5 ldrb r4, [r0] // Get next char 67 0058 0040C2E5 strb r4, [r2] // Write next char 68 69 005c 010080E2 add r0, r0, #1 70 0060 012082E2 add r2, r2, #1 71 72 0064 013043E2 sub r3, r3, #1 73 74 0068 F7FFFFEA b printLoop 75 76 printDone: 77 006c 2040A0E3 mov r4, #32 // Space 78 0070 0040C2E5 strb r4, [r2] 79 0074 012082E2 add r2, r2, #1 80 81 0078 003000E3 movw r3, #:lower16:stdout_end 82 007c 003040E3 movt r3, #:upper16:stdout_end // r2 = &stdout_end 83 0080 002083E5 str r2, [r3] 84 85 0084 1C00BDE8 pop {r2, r3, r4} // Restore scratch registers 86 0088 0EF0A0E1 mov pc, lr // Return 87 88 89 90 91 008c 00000500 stdout_start: .word 0x50000 // This value remains unchanged 92 0090 00000500 stdout_end: .word 0x50000 93 94 95 .end DEFINED SYMBOLS /home/egtapi/lib/cs255lib.s:11 .text:0000000000000000 malloc /home/egtapi/lib/cs255lib.s:53 .text:0000000000000038 print /home/egtapi/lib/cs255lib.s:91 .text:000000000000008c stdout_start /home/egtapi/lib/cs255lib.s:92 .text:0000000000000090 stdout_end /home/egtapi/lib/cs255lib.s:12 .text:0000000000000000 $a /home/egtapi/lib/cs255lib.s:38 .text:0000000000000034 maddr /home/egtapi/lib/cs255lib.s:38 .text:0000000000000034 $d /home/egtapi/lib/cs255lib.s:54 .text:0000000000000038 $a /home/egtapi/lib/cs255lib.s:62 .text:000000000000004c printLoop /home/egtapi/lib/cs255lib.s:76 .text:000000000000006c printDone /home/egtapi/lib/cs255lib.s:91 .text:000000000000008c $d NO UNDEFINED SYMBOLS