fixed up some bad comments in boot.asm

This commit is contained in:
Gregory Kenneth Bowne 2024-03-24 19:38:29 -07:00
parent 6c4ee8ed02
commit a6f5bdb64c
8 changed files with 137 additions and 183 deletions

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.vscode/browse.vc.db vendored

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11
.vscode/launch.json vendored
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@ -4,6 +4,7 @@
// For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
"version": "0.2.0",
"configurations": [
{
"name": "gcc-8 - Build and debug active file Level 1",
"type": "cppdbg",
@ -27,6 +28,16 @@
"logging": {
"engineLogging": true
}
},
{
"name": "Debug with QEMU",
"type": "cppdbg",
"request": "launch",
"program": "${workspaceFolder}/boot.bin",
"miDebuggerPath": "/usr/bin/qemu-system-i386",
"miDebuggerArgs": "-kernel",
"cwd": "${workspaceFolder}",
"preLaunchTask": "build"
}
]
}

165
.vscode/settings.json vendored
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@ -1,113 +1,66 @@
{
"files.associations": {
"*.c": "c",
"*.h": "c",
"*.cpp": "cpp",
"*.hpp": "hpp",
"*.asm": "asm",
"*.bin": "bin"
},
"files.fileAssociations": {
".c": "c",
".h": "c",
".cpp": "cpp",
".hpp": "cpp",
".asm": "asm",
".bin": "bin"
},
"emmet.includeLanguages": {
"c": "c",
"cpp": "cpp",
"assembly": "asm"
},
"C_Cpp_Runner.cCompilerPath": "/usr/bin",
"C_Cpp_Runner.cppCompilerPath": "/usr/bin",
"C_Cpp_Runner.debuggerPath": "/usr/bin",
"C_Cpp_Runner.cStandard": "c17",
"C_Cpp_Runner.cppStandard": "c++20",
"C_Cpp_Runner.msvcBatchPath": "C:/Program Files/Microsoft Visual Studio/2022/Community/VC/Auxiliary/Build/vcvarsall.bat",
"C_Cpp_Runner.useMsvc": false,
"C_Cpp_Runner.warnings": [
"-Wall",
"-Wextra",
"-Wextra",
"-Wpedantic"
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"C_Cpp_Runner.warningsAsError": false,
"C_Cpp_Runner.compilerArgs": [],
"C_Cpp_Runner.linkerArgs": [
"-dynamic-linker {/lib64/ld-linux-x86-64.so.2}"
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"C_Cpp_Runner.includePaths": [],
"C_Cpp_Runner.includeSearch": [
"*",
"**/*"
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"**/build/**",
"**/.*",
"**/.*/**",
"**/.vscode",
"**/.vscode/**"
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"C_Cpp_Runner.useAddressSanitizer": false,
"C_Cpp_Runner.showCompilationTime": false,
"c-cpp-flylint.enable": true,
"c-cpp-flylint.debug": true,
"c-cpp-flylint.flexelint.enable": false,
"c-cpp-flylint.cppcheck.enable": true,
"c-cpp-flylint.clang.enable": false,
"C_Cpp_Config.cCompilerPath": "gcc",
"C_Cpp_Config.cppCompilerPath": "g++",
"C_Cpp_Config.debuggerPath": "gdb",
"C_Cpp_Config.makePath": "make",
// General C/C++ settings
"C_Cpp.autoAddFileAssociations": true,
"C_Cpp.autocompleteAddParentheses": true,
"C_Cpp.clang_format_sortIncludes": true,
"C_Cpp.vcFormat.indent.preserveComments": true,
"C_Cpp.vcFormat.indent.namespaceContents": false,
"C_Cpp.vcFormat.indent.caseContentsWhenBlock": true,
"C_Cpp.vcFormat.space.pointerReferenceAlignment": "right",
"C_Cpp.default.browse.limitSymbolsToIncludedHeaders": false,
"C_Cpp.default.cppStandard": "c++20",
"C_Cpp.default.cStandard": "c17",
"C_Cpp.formatting": "clangFormat",
"[c]": {
"editor.formatOnSave": true,
"editor.defaultFormatter": "ms-vscode.cpptools"
},
"[cpp]": {
"editor.formatOnSave": true,
"editor.defaultFormatter": "ms-vscode.cpptools"
},
"C_Cpp.codeAnalysis.clangTidy.enabled": true,
"C_Cpp.configurationWarnings": "disabled",
"cmake.configureOnOpen": false,
"C_Cpp.configurationWarnings": "enabled",
"C_Cpp.default.browse.limitSymbolsToIncludedHeaders": false,
"C_Cpp.default.cStandard": "c11",
"C_Cpp.default.compilerPath": "",
"C_Cpp.default.cppStandard": "c++11",
"C_Cpp.default.enableConfigurationSquiggles": true,
"C_Cpp.errorSquiggles": "enabledIfIncludesResolve",
"C_Cpp.formatting": "default",
"C_Cpp.loggingLevel": "Debug",
"C_Cpp.vcFormat.indent.caseContentsWhenBlock": true,
"C_Cpp.vcFormat.indent.namespaceContents": false,
"C_Cpp.vcFormat.indent.preserveComments": true,
"C_Cpp.vcFormat.space.pointerReferenceAlignment": "right",
// CMake integration settings
"cmake.autoSelectActiveFolder": false,
"cmake.configureOnEdit": false,
"c-cpp-flylint.flexelint.configFile": "",
"c-cpp-flylint.flexelint.executable": "",
"c-cpp-flylint.language": "c",
"C_Cpp.autocompleteAddParentheses": true,
"C_Cpp.errorSquiggles": "enabled",
"C_Cpp_Runner.makePath": "",
"cmake.sourceDirectory": "${workspaceFolder}",
"C_Cpp.default.compilerPath": "/usr/bin",
"C_Cpp.loggingLevel": "Error",
"C_Cpp.default.enableConfigurationSquiggles": true,
"C_Cpp.default.includePath": [
"${workspaceFolder}/**", // Include all files in the workspace folder
"/usr/include", // Standard system include path
"/usr/local/include", // Additional system include path
"/path/to/custom/includes" // Custom include path
],
"workbench.editorAssociations": {
"*.bin": "default",
"*.h": "default",
"*.c": "default",
"*.json": "default",
"*.asm": "default"
"cmake.configureOnOpen": false,
"cmake.cmakePath": "/usr/bin/cmake",
"cmake.sourceDirectory": "${workspaceFolder}/",
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"[c]": {
"editor.defaultFormatter": "ms-vscode.cpptools",
"editor.formatOnSave": true
},
"C_Cpp.default.intelliSenseMode": "linux-gcc-x86",
"cmake.cmakePath": "/usr/bin/cmake"
"[cpp]": {
"editor.defaultFormatter": "ms-vscode.cpptools",
"editor.formatOnSave": true
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"*.cpp": "cpp",
"*.h": "c",
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"*.c": "default",
"*.cpp": "default",
"*.h": "default",
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"/usr/include",
"${workspaceFolder}/**",
"${workspaceFolder}/src/include",
"${workspaceFolder}/include"
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"/usr/include",
"${workspaceFolder}/**",
"${workspaceFolder}/src/include",
"${workspaceFolder}/include"
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"C_Cpp.default.configurationProvider": "ms-vscode.cpptools",
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}

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@ -16,10 +16,10 @@ identify_drive:
cmp cl, 0x80 ; Check for hard disk interrupt vector (example)
je is_harddrive
; Handle invalid drive type (error handling)
...
; ...
is_floppy:
Perform floppy disk access (assuming AH=0x02 for read sectors)
; Perform floppy disk access (assuming AH=0x02 for read sectors)
mov ah, 0x02 ; Read sectors
mov al, 1 ; Number of sectors to read (1)
@ -68,8 +68,8 @@ memory_error:
; ... (error handling or continue with limited memory)
; Second stage loading (simplified example)
Here's an improved version of the load_second_stage section with the placeholder jump replaced by actual loading logic:
Code snippet
; Here's an improved version of the load_second_stage section with the placeholder jump replaced by actual loading logic:
; Code snippet
load_second_stage:
; Calculate address of second stage bootloader (assuming offset from boot sector)

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@ -8,8 +8,7 @@ start:
MOV SP, 0xFFFF ; Stack grows downwards from the top of the segment
; Copy boot sector data to a safe location
mCopyBootSector
call mCopyBootSector
; Load the kernel
CALL load_kernel
@ -29,9 +28,7 @@ start:
mov es, ax ; Set other segment registers (ES, SS, etc.) as needed
RET
enable_a20:
; Enable A20 gate
cli ; Disable interrupts to prevent interference
call a20wait ; Wait for the keyboard controller to be ready
mov al, 0xAD ; Command to disable keyboard
@ -42,13 +39,13 @@ start:
call a20wait ; Wait for the keyboard controller to be ready
in al, 0x60 ; Read current state of output port
or al, 0x02 ; Set A20 bit
out 0x64, al ; Send command to keyboard controller command port
call a20wait ; Wait for the keyboard controller to be ready
mov al, 0xD1 ; Command to write output port
out 0x64, al ; Send command to keyboard controller command port
call a20wait ; Wait for the keyboard controller to be ready
mov al, 0x02 ; New output port data with A20 enabled
out 0x60, al ; Write new output port data
call a20wait ; Wait for the keyboard controller to be ready
mov al, 0xAE ; Command to re-enable keyboard
out 0x64, al ; Send command to keyboard controller command port
sti ; Re-enable interrupts
ret
@ -66,32 +63,28 @@ start:
; This involves setting up the segment registers with selectors
; that point to descriptors in the GDT that define a flat memory model
; Define GDT structure
limit = 0x00CFFFFFh ; Define limit as a separate variable within gdt_struct
; Placeholder instruction to satisfy NASM
dummy_instruction DB 0x90 ; NOP instruction as a placeholder
gdt_struct:
base_addr equ 0x0000000
; Null descriptor (ignored)
dq 0x0000000000000000h
dq 0x0000000000000000h
dd base_addr, 0 ; Both values are zero for a null descriptor
; Code segment descriptor (flat memory model)
; Base address 0, limit 0xffffffff (full 4GB)
; Present, Readable, Accessed, Code segment, 4KB granularity
; Flags: 0x9A (Bits explained below)
dq 0x0000000000000000h
dq 0x00CFFFFFFFh
dd base_addr, limit
db 0x9A
db 0xCF
; Data segment descriptor (flat memory model)
; Similar structure to code segment descriptor with Data segment flag set
dq 0x0000000000000000h
dq 0x00CFFFFFFFh
dd base_addr, limit
db 0x92
db 0xCF
; Jump to the kernel entry point
JMP 0x1000:0x0000 ; Assuming the kernel is loaded at 0x1000:0x0000
; Macro to copy boot sector data to a safe location
mCopyBootSector:
pusha ; Save all general-purpose registers

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@ -28,7 +28,4 @@ SECTIONS {
bootloader_padding : {
*(.bootloader_padding)
}
/* Set the bootloader size to 512 bytes */
= 512;
}