diff options
Diffstat (limited to 'src/arch/i386/prefix/libprefix.S')
| -rw-r--r-- | src/arch/i386/prefix/libprefix.S | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/src/arch/i386/prefix/libprefix.S b/src/arch/i386/prefix/libprefix.S index 406dac393..bf26358a9 100644 --- a/src/arch/i386/prefix/libprefix.S +++ b/src/arch/i386/prefix/libprefix.S @@ -43,6 +43,114 @@ #define CR0_PE 1 +/***************************************************************************** + * Utility function: print character (with LF -> LF,CR translation) + * + * Parameters: + * %al : character to print + * Returns: + * Nothing + * Corrupts: + * %ax + ***************************************************************************** + */ + .section ".prefix.lib" + .code16 + .globl print_character +print_character: + /* Preserve registers */ + pushw %bx + pushw %bp + /* Print character */ + movw $0x0007, %bx /* page 0, attribute 7 (normal) */ + movb $0x0e, %ah /* write char, tty mode */ + cmpb $0x0a, %al /* '\n'? */ + jne 1f + int $0x10 + movb $0x0d, %al +1: int $0x10 + /* Restore registers and return */ + popw %bp + popw %bx + ret + .size print_character, . - print_character + +/***************************************************************************** + * Utility function: print a NUL-terminated string + * + * Parameters: + * %ds:si : string to print + * Returns: + * %ds:si : character after terminating NUL + ***************************************************************************** + */ + .section ".prefix.lib" + .code16 + .globl print_message +print_message: + /* Preserve registers */ + pushw %ax + /* Print string */ +1: lodsb + testb %al, %al + je 2f + call print_character + jmp 1b +2: /* Restore registers and return */ + popw %ax + ret + .size print_message, . - print_message + +/***************************************************************************** + * Utility functions: print hex digit/byte/word/dword + * + * Parameters: + * %al (low nibble) : digit to print + * %al : byte to print + * %ax : word to print + * %eax : dword to print + * Returns: + * Nothing + ***************************************************************************** + */ + .section ".prefix.lib" + .code16 + .globl print_hex_dword +print_hex_dword: + rorl $16, %eax + call print_hex_word + rorl $16, %eax + /* Fall through */ + .size print_hex_dword, . - print_hex_dword + .globl print_hex_word +print_hex_word: + xchgb %al, %ah + call print_hex_byte + xchgb %al, %ah + /* Fall through */ + .size print_hex_word, . - print_hex_word + .globl print_hex_byte +print_hex_byte: + rorb $4, %al + call print_hex_nibble + rorb $4, %al + /* Fall through */ + .size print_hex_byte, . - print_hex_byte + .globl print_hex_nibble +print_hex_nibble: + /* Preserve registers */ + pushw %ax + /* Print digit (technique by Norbert Juffa <norbert.juffa@amd.com> */ + andb $0x0f, %al + cmpb $10, %al + sbbb $0x69, %al + das + call print_character + /* Restore registers and return */ + popw %ax + ret + .size print_hex_nibble, . - print_hex_nibble + /**************************************************************************** * pm_call (real-mode near call) * |