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Diffstat (limited to 'boot/common-boot.s')
| -rw-r--r-- | boot/common-boot.s | 368 |
1 files changed, 0 insertions, 368 deletions
diff --git a/boot/common-boot.s b/boot/common-boot.s deleted file mode 100644 index 9305d40..0000000 --- a/boot/common-boot.s +++ /dev/null @@ -1,368 +0,0 @@ -# This Source Code Form is subject to the terms of the Mozilla Public License, -# v. 2.0. If a copy of the MPL was not distributed with this file, You can -# obtain one at https://mozilla.org/MPL/2.0/. - -.global _read_file, _write_error -.global _memcmp, _memchr, _memmem, _mmap -.global _current, _get, _advance, _label_counter -.global _divide_by_zero_error, _strings_index, _string_equal - -.section .rodata - -.equ SYS_READ, 63 -.equ SYS_WRITE, 64 -.equ SYS_MMAP2, 222 -.equ STDIN, 0 -.equ STDOUT, 1 -.equ STDERR, 2 -.equ PROT_READ, 0x1 -.equ PROT_WRITE, 0x2 -.equ MAP_PRIVATE, 0x02 -.equ MAP_ANONYMOUS, 0x20 - -new_line: .ascii "\n" - -.section .text - -# Write the current token to stderr. Ends the output with a newline. -# -# a0 - String pointer. -# a1 - String length. -.type _write_error, @function -_write_error: - mv t0, a0 - mv t1, a1 - - li a0, STDERR - mv a1, t0 - mv a2, t1 - li a7, SYS_WRITE - ecall - - li a0, STDERR - la a1, new_line - li a2, 1 - li a7, SYS_WRITE - ecall - - ret - -# a0 - First pointer. -# a1 - Second pointer. -# a2 - The length to compare. -# -# Returns 0 in a0 if memory regions are equal. -.type _memcmp, @function -_memcmp: - mv t0, a0 - li a0, 0 - -.Lmemcmp_loop: - beqz a2, .Lmemcmp_end - - lbu t1, (t0) - lbu t2, (a1) - sub a0, t1, t2 - - bnez a0, .Lmemcmp_end - - addi t0, t0, 1 - addi a1, a1, 1 - addi a2, a2, -1 - - j .Lmemcmp_loop - -.Lmemcmp_end: - ret - -# Reads standard input into a buffer. -# a0 - Buffer pointer. -# a1 - Buffer size. -# -# Sets s1 to the buffer passed in a0. -# -# Returns the amount of bytes written in a0. -.type _read_file, @function -_read_file: - # Prologue. - addi sp, sp, -8 - sw ra, 4(sp) - sw s0, 0(sp) - addi s0, sp, 8 - - mv s1, a0 - - li a0, STDIN - mv a2, a1 - mv a1, s1 - li a7, SYS_READ - ecall - - # Epilogue. - lw ra, 4(sp) - lw s0, 0(sp) - addi sp, sp, 8 - ret - -.type _divide_by_zero_error, @function -_divide_by_zero_error: - addi a7, zero, 172 # getpid - ecall - - addi a1, zero, 8 # SIGFPE - addi a7, zero, 129 # kill - ecall - ret - -# a0 - Pointer to an array to get the first element. -# -# Dereferences a pointer and returns what is on the address in a0. -.type _get, @function -_get: - lw a0, (a0) - ret - -# Searches for the occurences of a character in the given memory block. -# -# Parameters: -# a0 - Memory block. -# a1 - Needle. -# a2 - Memory size. -# -# Sets a0 to the pointer to the found character or to null if the character -# doesn't occur in the memory block. -.type _memchr, @function -_memchr: -.Lmemchr_loop: - beqz a2, .Lmemchr_nil # Exit if the length is 0. - - lbu t0, (a0) # Load the character from the memory block. - beq t0, a1, .Lmemchr_end # Exit if the character was found. - - # Otherwise, continue with the next character. - addi a0, a0, 1 - addi a2, a2, -1 - - j .Lmemchr_loop - -.Lmemchr_nil: - li a0, 0 - -.Lmemchr_end: - ret - -# Locates a substring. -# -# Parameters: -# a0 - Haystack. -# a1 - Haystack size. -# a2 - Needle. -# a3 - Needle size. -# -# Sets a0 to the pointer to the beginning of the substring in memory or to 0 -# if the substring doesn't occur in the block. -.type _memmem, @function -_memmem: - # Prologue. - addi sp, sp, -24 - sw ra, 20(sp) - sw s0, 16(sp) - addi s0, sp, 24 - - # Save preserved registers. They are used to keep arguments. - sw s1, 12(sp) - sw s2, 8(sp) - sw s3, 4(sp) - sw s4, 0(sp) - - mv s1, a0 - mv s2, a1 - mv s3, a2 - mv s4, a3 - -.Lmemmem_loop: - blt s2, s3, .Lmemmem_nil # Exit if the needle length is greater than memory. - - mv a0, s1 - mv a1, s3 - mv a2, s4 - call _memcmp - - mv t0, a0 # memcmp result. - mv a0, s1 # Memory pointer for the case the substring was found. - beqz t0, .Lmemmem_end - - addi s1, s1, 1 - add s2, s2, -1 - - j .Lmemmem_loop - -.Lmemmem_nil: - li a0, 0 - -.Lmemmem_end: - - # Restore the preserved registers. - lw s1, 12(sp) - lw s2, 8(sp) - lw s3, 4(sp) - lw s4, 0(sp) - - # Epilogue. - lw ra, 20(sp) - lw s0, 16(sp) - add sp, sp, 24 - ret - -# Searches for a string in a string array. -# -# Parameters: -# a0 - Number of elements in the string array. -# a1 - String array. -# a2 - Needle length. -# a3 - Needle. -# -# Sets a0 to the 1-based index of the needle in the haystack or to 0 if the -# element could not be found. -.type _strings_index, @function -_strings_index: - # Prologue. - addi sp, sp, -32 - sw ra, 28(sp) - sw s0, 24(sp) - addi s0, sp, 32 - - sw s1, 20(sp) - mv s1, a0 - sw s2, 16(sp) - mv s2, a1 - sw s3, 12(sp) - mv s3, a2 - sw s4, 8(sp) - mv s4, a3 - sw s5, 4(sp) - li s5, 0 # Index counter. - -.Lstrings_index_loop: - addi s5, s5, 1 - beqz s1, .Lstrings_index_missing - - lw a2, (s2) # Read the length of the current element in the haystack. - bne a2, s3, .Lstrings_index_next # Lengths don't match, skip the iteration. - - addi a0, s2, 4 - mv a1, s4 - call _memcmp - - beqz a0, .Lstrings_index_end - -.Lstrings_index_next: - # Advance the pointer, reduce the length. - lw a2, (s2) - addi s2, s2, 4 - add s2, s2, a2 - addi s1, s1, -1 - j .Lstrings_index_loop - -.Lstrings_index_missing: - li s5, 0 - -.Lstrings_index_end: - mv a0, s5 - - lw s1, 20(sp) - lw s2, 16(sp) - lw s3, 12(sp) - lw s4, 8(sp) - lw s5, 4(sp) - - # Epilogue. - lw ra, 28(sp) - lw s0, 24(sp) - add sp, sp, 32 - ret - -# Compares two strings for equality. -# -# Parameters: -# a0 - Length of the first string. -# a1 - Pointer to the first string. -# a2 - Length of the second string. -# a3 - Pointer to the second string. -# -# Sets a0 to 1 if the string are equal, to 0 if not. -.type _string_equal, @function -_string_equal: - # Prologue. - addi sp, sp, -32 - sw ra, 28(sp) - sw s0, 24(sp) - addi s0, sp, 32 - - # Compare string lengths. - bne a0, a2, .Lstring_equal_not_found - - # If lengths match, compare the content. - mv a0, a1 - mv a1, a3 - # a2 is already set to the length. - call _memcmp - - bnez a0, .Lstring_equal_not_found - - li a0, 1 - j .Lstring_equal_end - -.Lstring_equal_not_found: - mv a0, zero - -.Lstring_equal_end: - # Epilogue. - lw ra, 28(sp) - lw s0, 24(sp) - addi sp, sp, 32 - ret - -# Sets a0 to the mapping address. -.type _mmap, @function -_mmap: - li a0, 0 # Address at which to create the mapping. - li a1, 4096 # The length of the mapping. - li a2, PROT_READ | PROT_WRITE # Protection flags. - li a3, MAP_ANONYMOUS | MAP_PRIVATE # The mapping is not backed by a file. - li a4, -1 # File descriptor. - li a5, 0 # Page offset. - li a7, SYS_MMAP2 - ecall - - ret - -# Sets the a0 to the current position in the source text (s1). -.type _current, @function -_current: - mv a0, s1 - ret - -# Advances the position of the source text. -# -# Parameters: -# a0 - The number of bytes to advance. -.type _advance, @function -_advance: - add s1, s1, a0 - ret - -# Advances the global label counter by 1 setting a0 to the previous value. -# -# Parameters: -# a0 - If it is 0, resets the counter to 1. -.type _label_counter, @function -_label_counter: - bnez a0, .Llabel_counter_advance - li s2, 0 - -.Llabel_counter_advance: - mv a0, s2 - addi s2, s2, 1 - - ret |