After having considered some comments from Mr.\/Ms. G I optimized my assembly code a little bit.
\nHere a better approach:<\/p>\n
Output<\/strong> 11011110101011011011111011101111 <\/p>\n 00000000111111111111111111111111<\/p>\n Code:<\/strong><\/p>\n After having considered some comments from Mr.\/Ms. G I optimized my assembly code a little bit. Here a better approach: Output deadbeef 11011110101011011011111011101111 00000000111111111111111111111111 Code: .equ STRING_LENGTH, 32 .equ ZERO_CHARACTER, 0x30 .equ ONE_CHARACTER, 0x31 .data Mask: .ascii “%x\\n\\n” .align 4 varToPrint: .long 0xdeadbeef .balign 8 varToUnspace: .long 0xdeadbeef .balign 8 unspacedVarToPrint: .long 0xdeadbeef .balign 8 … Continue reading ARM assembly, take 3<\/span>
\ndeadbeef<\/p>\n\r\n.equ STRING_LENGTH, 32\r\n.equ ZERO_CHARACTER, 0x30\r\n.equ ONE_CHARACTER, 0x31\r\n\r\n.data\r\nMask:\r\n\t.ascii \"%x\\n\\n\"\r\n.align 4 \r\n\r\nvarToPrint:\r\n\t.long 0xdeadbeef\r\n.balign 8 \r\n\r\nvarToUnspace:\r\n\t.long 0xdeadbeef\r\n.balign 8 \r\n\r\nunspacedVarToPrint:\r\n\t.long 0xdeadbeef\r\n.balign 8 \r\n\r\nstringToPrint:\r\n\t.ascii \" \\n\\n\"\r\nlen = STRING_LENGTH\r\n.balign STRING_LENGTH\r\n\r\nunspacedStringToPrint:\r\n\t.ascii \" \\n\\n\"\r\nlen = STRING_LENGTH\r\n.balign STRING_LENGTH\r\n\r\n.text\r\n.globl main\r\nmain:\r\n\tstmfd\tsp!, {r0, r1, r2, r3, r4, r5, r6, r7, lr}\t@ save the registers we use to the stack\r\n\r\n\tldr\tr3, AddrVarToPrint\r\n\tldr\tr6, [r3]\r\n\tldr\tr3, AddrVarToPrint\r\n\tstr\tr6, [r3]\r\n\r\n\t\/*\r\n\tGenerating string of binary representation:\r\n\t\tAddress of variable in r0\r\n\t\tAddress of target string in r1\r\n\t*\/\r\n\tldr\tr0, AddrVarToPrint\r\n\tldr\tr1, AddrStringToPrint\r\n\tbl make_binary_number\r\n\t\/*------------------------------------------*\/\r\n\r\n\t\/*\r\n\tRemoving zeroes between the ones in binary value:\r\n\t\tAddress of variable in r0\r\n\t\tAddress of target variable in r1\r\n\t*\/\r\n\tldr\tr0, AddrVarToPrint\r\n\tldr\tr1, AddrUnspacedVarToPrint\r\n\tbl remove_spaces\r\n\r\n\t\/*\r\n\tGenerating string of binary representation:\r\n\t\tAddress of variable in r0\r\n\t\tAddress of target string in r1\r\n\t*\/\r\n\tldr\tr0, AddrUnspacedVarToPrint\r\n\tldr\tr1, AddrUnspacedStringToPrint\r\n\tbl make_binary_number\r\n\t\/*------------------------------------------*\/\r\n\r\n\tbl print_out_result\r\n\r\n\tb exit\r\n\r\n\/*-Fetching the values and printing them-----------------------*\/\r\nprint_out_result:\r\n\tpush\t{r0, r1, r2, r3, r4, lr}\r\n\r\n\tldr r3, AddrMask\r\n\tmovs\tr0, r3\r\n\tldr\tr3, AddrVarToPrint\r\n\tldr\tr1, [r3]\r\n\tbl\tprintf\r\n\r\n\tldr r3, AddrStringToPrint \r\n\tmovs\tr0, r3\r\n\tbl\tprintf\r\n\r\n\tldr r3, AddrUnspacedStringToPrint\r\n\tmovs\tr0, r3\r\n\tbl\tprintf\r\n\r\n\tpop\t{r0, r1, r2, r3, r4, pc}\r\n\r\n\/*-Generate a binary representation string from integer--------*\/\r\n\/* Address of variable in r0 *\/\r\n\/* Address of target string in r1 *\/\r\nmake_binary_number:\r\n\tpush\t{r2, r3, r4, r5, r6, r7, lr}\r\n\tldr\tr3, [r0] \/* integer value of variable *\/\r\n\r\n\tmovs\tr4, $0 \/* loop counter *\/\r\nbin_loop:\r\n\tmovs r2, $0x1\r\n\tlsls\tr2, r4 \/* r2 = (0x01 >> counter) *\/\r\n\r\n\tmovs\tr6, $STRING_LENGTH-1\r\n\tsubs\tr6, r6, r4 \/* idx = reg_length-counter *\/\r\n\r\n\ttst\tr3, r2\r\n\tbeq\tno_one\r\n\r\n\tmovs\tr5, $ONE_CHARACTER\r\n\tstrb\tr5, [r1,r6]\r\n\tb end_bin_loop\r\n\r\nno_one:\r\n\tmovs\tr5, $ZERO_CHARACTER\r\n\tstrb\tr5, [r1,r6]\r\n\tb end_bin_loop\r\n\r\nend_bin_loop:\r\n\tadds\tr4, r4,$1\r\n\tcmp\tr4, $STRING_LENGTH\r\n\tbne\tbin_loop\r\n\r\n\tpop\t{r2, r3, r4, r5, r6, r7, pc}\r\n\r\n\/*-Removes spaces between ones---------------------------------*\/\r\n\/* Taken we have: 0xdeadbeef\r\n\tBinary representation: 11011110101011011011111011101111\r\n\tThen the ones will be shifted together so that we get\r\n\tthe following result: 00000000111111111111111111111111\r\n*\/\r\n\/* Address of variable in r0 *\/\r\n\/* Address of target variable in r1 *\/\r\nremove_spaces:\r\n\tpush\t{r2, r3, r4, r5, r6, r7, lr}\r\n\tldr\tr6, [r0]\r\n\r\n\tmovs\tr4, $0\r\n\tmovs\tr5, $0\r\n\tmovs\tr7, $0\r\n\r\nunspace_loop:\r\n\tmovs r2, $0x1\r\n\r\n\tlsls\tr2, r4\r\n\r\n\ttst\tr6, r2\r\n\tbeq\tend_unspace_loop\r\n\r\n\tlsls\tr5, r5, $1\r\n\tadds\tr5, r5, $1\r\n\r\nend_unspace_loop:\r\n\tadds\tr4, r4,$1\r\n\tcmp\tr4, $STRING_LENGTH\r\n\tbne\tunspace_loop\r\n\r\n\tstr\tr5, [r1]\r\n\r\n\tpop\t{r2, r3, r4, r5, r6, r7, pc}\r\n\/*-------------------------------------------------------------*\/\r\n\r\n\/*--------EXIT main(void) function -> return 0-----------------*\/\r\nexit:\r\n\tldmfd\tsp!, {r0, r1, r2, r3, r4, r5, r6, r7, pc}\t@ restore registers before exit\r\n\tmovs\tr7, $1 @ set r7 to 1 - the syscall for exit\r\n\tswi\t0 @ then invoke the syscall from linux\r\n\r\n\r\n\/*-----Variable pointers---------------------------------------*\/\r\nAddrMask:\r\n\t.word\tMask\r\n\r\nAddrVarToPrint:\r\n\t.long\tvarToPrint\r\n\r\nAddrVarToUnspace:\r\n\t.long\tvarToUnspace\r\n\r\nAddrStringToPrint:\r\n\t.word stringToPrint\r\n\r\nAddrUnspacedStringToPrint:\r\n\t.word unspacedStringToPrint\r\n\r\nAddrUnspacedVarToPrint:\r\n\t.long unspacedVarToPrint\r\n\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"