1 /* -------------------------------------------------- 2 Define required labels for EGTAPI 3 -------------------------------------------------- */ 4 .global main, Stop, CodeEnd, DataStart, DataEnd 5 6 .global a, b, x 7 8 /* -------------------------------------------------- 9 <----a b-----> 10 ------+----------+-------- 11 12 if (x <= a or x >= b) 13 x = x + 1; 14 else 15 x = x - 1; 16 -------------------------------------------------- */ 17 .text 18 main: 19 // Test if (x <= a ) 20 0000 000000E3 movw r0, #:lower16:x 21 0004 000040E3 movt r0, #:upper16:x // r0 = addr(x) 22 0008 000090E5 ldr r0, [r0] // r0 = x 23 24 000c 001000E3 movw r1, #:lower16:a 25 0010 001040E3 movt r1, #:upper16:a // r1 = addr(a) 26 0014 001091E5 ldr r1, [r1] // r1 = a 27 28 0018 010050E1 cmp r0, r1 // x <= a ? 29 001c 070000DA ble then // Branch to "then" if x <= a 30 31 // test if ( x >= b ) 32 0020 000000E3 movw r0, #:lower16:x 33 0024 000040E3 movt r0, #:upper16:x // r0 = addr(x) 34 0028 000090E5 ldr r0, [r0] // r0 = x 35 36 002c 001000E3 movw r1, #:lower16:b 37 0030 001040E3 movt r1, #:upper16:b // r1 = addr(b) 38 0034 001091E5 ldr r1, [r1] // r1 = b 39 40 0038 010050E1 cmp r0, r1 // x >= b ? 41 003c 050000BA blt else // Branch to "else" if x < b 42 43 then: 44 // x = x + 1 45 0040 000000E3 movw r0, #:lower16:x 46 0044 000040E3 movt r0, #:upper16:x // r0 = addr(x) 47 48 0048 001090E5 ldr r1, [r0] // r1 = x 49 004c 011081E2 add r1, r1, #1 // r1 = x+1 50 0050 001080E5 str r1, [r0] // x = x+1 51 52 0054 040000EA b ifEnd // ** SKIP over the else part !!! *** 53 54 else: 55 // x = x - 1 56 0058 000000E3 movw r0, #:lower16:x 57 005c 000040E3 movt r0, #:upper16:x // r0 = addr(x) 58 59 0060 001090E5 ldr r1, [r0] // r1 = x 60 0064 011041E2 sub r1, r1, #1 // r1 = x-1 61 0068 001080E5 str r1, [r0] // x = x-1 62 63 ifEnd: 64 65 Stop: 66 CodeEnd: 67 006c 0000A0E1 nop 68 69 /* -------------------------------------------------- 70 Begin of the permanent program variables 71 -------------------------------------------------- */ 72 .data 73 DataStart: 74 75 0000 05000000 x: .4byte 5 // Try x: 10 < x < 20 76 0004 0A000000 a: .4byte 10 77 0008 14000000 b: .4byte 20 78 79 DataEnd: 80 81 .end DEFINED SYMBOLS x.s:18 .text:0000000000000000 main x.s:65 .text:000000000000006c Stop x.s:66 .text:000000000000006c CodeEnd x.s:73 .data:0000000000000000 DataStart x.s:79 .data:000000000000000c DataEnd x.s:76 .data:0000000000000004 a x.s:77 .data:0000000000000008 b x.s:75 .data:0000000000000000 x x.s:20 .text:0000000000000000 $a x.s:43 .text:0000000000000040 then x.s:54 .text:0000000000000058 else x.s:63 .text:000000000000006c ifEnd 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