first commit

include/errors.inc

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+;    Copyright (C) 2020  Bradley Claus
+;
+;    This program is free software: you can redistribute it and/or modify
+;    it under the terms of the GNU General Public License as published by
+;    the Free Software Foundation, either version 3 of the License, or
+;    (at your option) any later version.
+;
+;    This program is distributed in the hope that it will be useful,
+;    but WITHOUT ANY WARRANTY; without even the implied warranty of
+;    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;    GNU General Public License for more details.
+;
+;    You should have received a copy of the GNU General Public License
+;    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+
+; Errors
+; 12 Errors, 5 in use
+%define MBR_ERROR_DISK_T_ERR         'a'
+%define MBR_ERROR_NO_INT32E          'b'
+%define MBR_ERROR_NO_NO_BOOT_PART    'c'
+%define MBR_ERROR_DISK_READ_ERR      'd'
+%define MBR_ERROR_NO_VBR_SIG         'e'
+%define MBR_ERROR_RESERVED_f         'f'
+%define MBR_ERROR_RESERVED_g         'g'
+%define MBR_ERROR_RESERVED_h         'h'
+%define MBR_ERROR_RESERVED_i         'i'
+%define MBR_ERROR_RESERVED_j         'j'
+%define MBR_ERROR_RESERVED_k         'k'
+%define MBR_ERROR_RESERVED_l         'l'
+
+; 12 Error
+%define VBR_ERROR_WRONG_FAT_SIZE     'm'
+%define VBR_ERROR_NO_SIGNATURE       'n'
+%define VBR_ERROR_DISK_READ_ERR      'o'
+%define VBR_ERROR_RESERVED_p         'p'
+%define VBR_ERROR_RESERVED_q         'q'
+%define VBR_ERROR_RESERVED_r         'r'
+%define VBR_ERROR_RESERVED_s         's'
+%define VBR_ERROR_RESERVED_t         't'
+%define VBR_ERROR_RESERVED_u         'u'
+%define VBR_ERROR_RESERVED_v         'v'
+%define VBR_ERROR_RESERVED_w         'w'
+%define VBR_ERROR_RESERVED_x         'x'
+
+; 26 errors, 8 in use
+%define STAGE2_A20_FAILED            'A'
+%define STAGE2_SIGNATURE_MISSING     'B'
+%define STAGE2_MM_E820_NO_SUPPORT    'C'
+%define STAGE2_MM_E820_MISC_ERR      'D'
+%define STAGE2_MM_E820_NONSTANDARD   'E'
+%define STAGE2_MM_E820_NO_SMAP       'F'
+%define STAGE2_MBR_DISK_READ_ERROR   'G'
+%define STAGE2_FAT32_INIT_ERROR      'H'
+%define STAGE2_FAT32_NO_FILE         'I'
+%define STAGE2_FAT32_END_OF_CHAIN    'J'
+%define STAGE2_ERROR_RESERVED_K      'K'
+%define STAGE2_ERROR_RESERVED_L      'L'
+%define STAGE2_ERROR_RESERVED_M      'M'
+%define STAGE2_ERROR_RESERVED_N      'N'
+%define STAGE2_ERROR_RESERVED_O      'O'
+%define STAGE2_ERROR_RESERVED_P      'P'
+%define STAGE2_ERROR_RESERVED_Q      'Q'
+%define STAGE2_ERROR_RESERVED_R      'R'
+%define STAGE2_ERROR_RESERVED_S      'S'
+%define STAGE2_ERROR_RESERVED_T      'T'
+%define STAGE2_ERROR_RESERVED_U      'U'
+%define STAGE2_ERROR_RESERVED_V      'V'
+%define STAGE2_ERROR_RESERVED_W      'W'
+%define STAGE2_ERROR_RESERVED_X      'X'
+%define STAGE2_ERROR_RESERVED_Y      'Y'
+%define STAGE2_ERROR_RESERVED_Z      'Z'
+
+
+%macro ERROR 1
+    mov al, %1
+    jmp error
+%endmacro
+
+; pass error as ascii character in al, errors a-zA-Z or 0-9
+error:
+    ; color 0x4F is white on red
+    ; fs = 0xb800 => fs:0x0000 = 0xb8000
+    mov dx, 0xB800
+    mov fs, dx
+
+    ; the characters are two bytes in the order of 0xb8000: byte c, byte attribute
+    ; since x86 is le, we store the attribute in the MSB of dx
+    mov dh, 0x4F
+    mov dl, al
+    mov word [fs:0x0000], dx
+
+.stop:
+    hlt
+    jmp short error.stop