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Diffstat (limited to 'src/lib/utils.s')
| -rw-r--r-- | src/lib/utils.s | 214 |
1 files changed, 0 insertions, 214 deletions
diff --git a/src/lib/utils.s b/src/lib/utils.s deleted file mode 100644 index f63d3f9..0000000 --- a/src/lib/utils.s +++ /dev/null @@ -1,214 +0,0 @@ -# These registers are not neccesarily perserved after a function call: -# RAX RCX RDX RSI RDI R8 R9 R10 R11 -# Which means that these must be perserved: -# RBX RBP R12 R13 R14 R15 -# The order of arguments passed to functions is as follows: -# RDI RSI RDX RCX R8 R9 -# The order of the return registers is as follows: -# RAX RDX - -# Buffer for file data -.section .data -myBuffer: - .space 1 - -.section .text - - -# Print RDI as an unsigned integer following by a newline. -# Note: the function does not follow the ordinary calling convention, -# but restores all registers. -.type printNum, @function -.globl printNum -printNum: - push %rbp - movq %rsp, %rbp - - # save - push %rax - push %rdi - push %rsi - push %rdx - push %rcx - push %r8 - push %r9 - - movq %rdi, %rax # arg - - movq $1, %r9 # we always print "\n" - push $10 # '\n' -.LprintNum_convertLoop: - movq $0, %rdx - movq $10, %rcx - idivq %rcx - addq $48, %rdx # '0' is 48 - push %rdx - addq $1, %r9 - cmpq $0, %rax - jne .LprintNum_convertLoop -.LprintNum_printLoop: - movq $1, %rax # sys_write - movq $1, %rdi # stdout - movq %rsp, %rsi # buf - movq $1, %rdx # len - syscall - addq $8, %rsp - addq $-1, %r9 - jne .LprintNum_printLoop - - # restore - pop %r9 - pop %r8 - pop %rcx - pop %rdx - pop %rsi - pop %rdi - pop %rax - - movq %rbp, %rsp - pop %rbp - ret - -.globl intFromString # int intFromString(char *str) -# Pre: str != 0 -# Pre: all characters in the string are one of 0123456789. -.type intFromString, @function -intFromString: - xorq %rax, %rax -.LintFromString_loop: - movzx (%rdi), %rsi # Move a single character/byte %rbx and zero-extend it. - cmpq $0, %rsi # A string ends with a 0-byte. - je .LintFromString_done - movq $10, %rcx # Shift the number 1 decimal place to the left. - mulq %rcx - subq $48, %rsi # Convert from ASCII character to number. ASCII '0' has value 48. '1' is 49, etc. - addq %rsi, %rax # Add the number. - addq $1, %rdi - jmp .LintFromString_loop -.LintFromString_done: - ret - - -# The pointer to the string is argument RDI -# It is required that the string ends with the zero byte -.type printString, @function -.globl printString -printString: - push %r12 # Save R12 - - movq %rdi, %r12 # Save copy of string address - call stringLength # Get length of string in RAX - - movq $1, %rdi # Select to write to stdout - movq %r12, %rsi # Use pointer at start of string - movq %rax, %rdx # Put string size in rdx - movq $1, %rax # Select sys_write - syscall # Call the function - - pop %r12 # Restore R12 - ret - - -# Requires that the file is already open, and file descriptor is passed as first -# argument. -.type printFile, @function -.globl printFile -printFile: - # The callee-saved registers - push %rbx - push %rbp - push %r12 - push %r13 - push %r14 - push %r15 - - movq %rdi, %r10 # Save file descriptor in r10 - -loop: - movq %r10, %rdi # Select the file discriptor - movq $0, %rax # Select read syscall - movq $1, %rdx # Size to read from file - movq $myBuffer, %rsi # Select the buffer to store input - syscall # Read from the file - - cmp $0, %rax # If rax is zero, end of file - je endPrintFile # Jump to end of program - - movq $1, %rdx # Put string size in RDX - movq $myBuffer, %rsi # Use pointer at start of string - movq $1, %rdi # Select to write to stdout - movq $1, %rax # Select sys_write - syscall # Call the function - - jmp loop - -endPrintFile: - # The callee-saved registers - pop %r15 - pop %r14 - pop %r13 - pop %r12 - pop %rbp - pop %rbx - - ret - - -.type printStdin, @function -.globl printStdin -printStdin: - # The callee-saved registers - push %rbx - push %rbp - push %r12 - push %r13 - push %r14 - push %r15 - -printStdinLoop: - movq $0, %rax # Select read syscall - movq $1, %rdx # Size to read - movq $0, %rdi # Select stdin - movq $myBuffer, %rsi # Select the buffer to store input - syscall - - cmp $0, %rax # Check if there was something to be read. - je endPrintStdin # If not, jump to end - - movq $1, %rdx # Put string size in rdx - movq $myBuffer, %rsi # Use pointer at start of string - movq $1, %rdi # Select to write to stdout - movq $1, %rax # Select sys_write - syscall # Call the function - - jmp printStdinLoop - - -endPrintStdin: - # The callee-saved registers - pop %r15 - pop %r14 - pop %r13 - pop %r12 - pop %rbp - pop %rbx - - ret - -.type stringLength, @function -.globl stringLength -stringLength: - movq $0, %rcx # CL will keep the current byte - movq $0, %rax # The length counter - -loopStringLength: - movb (%rdi), %cl # Move the lower byte of the string into CL - cmp $0, %cl # Compare 0 with the lower byte of register C - je endStringLength # Go the end - addq $1, %rax # Add one to length - addq $1, %rdi # Go one forward in address - jmp loopStringLength# Go to start of loop - -endStringLength: - ret - |