source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS_Configurator_v2/Src/EEPROM.asm @ 138

; Project name  :   XTIDE Univeral BIOS Configurator v2
; Author        :   Tomi Tilli
; Description   :   Functions for managing EEPROM contents.

; Section containing initialized data
SECTION .data

ALIGN WORD_ALIGN
g_rgwEepromTypeToSizeInWords:
    dw      (2<<10) / 2     ; EEPROM_TYPE.2816_2kiB
    dw      (8<<10) / 2
    dw      (32<<10) / 2
    dw      (64<<10) / 2

g_rgwEepromPageToSizeInBytes:
    dw      1               ; EEPROM_PAGE.1_byte
    dw      2
    dw      4
    dw      8
    dw      16
    dw      32
    dw      64



; Section containing code
SECTION .text

;--------------------------------------------------------------------
; EEPROM_GetSmallestEepromSizeInWordsToCXforImageWithWordSizeInAX
;   Parameters:
;       AX:     Image size in WORDs
;   Returns:
;       CX:     Required EEPROM size in WORDs
;       CF:     Set if EEPROM size found
;               Cleared if no valid EEPROM found
;   Corrupts registers:
;       BX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
EEPROM_GetSmallestEepromSizeInWordsToCXforImageWithWordSizeInAX:
    mov     bx, g_rgwEepromTypeToSizeInWords
    mov     cx, NUMBER_OF_EEPROM_TYPES
ALIGN JUMP_ALIGN
.CheckNextEepromSize:
    cmp     ax, [cs:bx]
    jbe     SHORT .ReturnEepromSizeInCX
    inc     bx
    inc     bx
    loop    .CheckNextEepromSize
    clc     ; None of the supported EEPROMs are large enough
    ret
ALIGN JUMP_ALIGN
.ReturnEepromSizeInCX:
    mov     cx, [cs:bx]
    stc
    ret


;--------------------------------------------------------------------
; EEPROM_LoadXtideUniversalBiosFromRomToRamBufferAndReturnSizeInDXCX
;   Parameters:
;       Nothing
;   Returns:
;       DX:CX:  BIOS size in bytes
;   Corrupts registers:
;       AX, BX, SI, DI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
EEPROM_LoadXtideUniversalBiosFromRomToRamBufferAndReturnSizeInDXCX:
    push    es

    call    EEPROM_FindXtideUniversalBiosROMtoESDI
    call    .GetXtideUniversalBiosSizeFromEStoDXCX
    xor     si, si              ; Load from beginning of ROM
    call    LoadBytesFromRomToRamBuffer

    call    .GetXtideUniversalBiosSizeFromEStoDXCX
    pop     es
    ret

;--------------------------------------------------------------------
; .GetXtideUniversalBiosSizeFromEStoDXCX
;   Parameters:
;       Nothing
;   Returns:
;       DX:CX:  Bios size in bytes
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
.GetXtideUniversalBiosSizeFromEStoDXCX:
    xor     dx, dx
    eMOVZX  cx, BYTE [es:ROMVARS.bRomSize]
    eSHL_IM cx, 9               ; *= 512 for byte count
    ret


;--------------------------------------------------------------------
; EEPROM_LoadOldSettingsFromRomToRamBuffer
;   Parameters:
;       Nothing
;   Returns:
;       CF:     Set if EEPROM was found
;               Cleared if EEPROM not found
;   Corrupts registers:
;       AX, BX, CX, SI, DI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
EEPROM_LoadOldSettingsFromRomToRamBuffer:
    mov     cx, ROMVARS_size - ROMVARS.wFlags   ; Number of bytes to load
    mov     si, ROMVARS.wFlags                  ; Offset where to start loading
    ; Fall to LoadBytesFromRomToRamBuffer

;--------------------------------------------------------------------
; LoadBytesFromRomToRamBuffer
;   Parameters:
;       CX:     Number of bytes to load from ROM
;       SI:     Offset to first byte to load
;   Returns:
;       CF:     Set if EEPROM was found
;               Cleared if EEPROM not found
;   Corrupts registers:
;       AX, BX, CX, SI, DI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
LoadBytesFromRomToRamBuffer:
    push    es
    push    ds

    call    EEPROM_FindXtideUniversalBiosROMtoESDI
    jnc     SHORT .XtideUniversalBiosNotFound
    push    es
    pop     ds                                          ; DS:SI points to ROM

    call    Buffers_GetFileBufferToESDI
    mov     di, si                                      ; ES:DI points to RAM buffer

    cld
    call    Memory_CopyCXbytesFromDSSItoESDI
    stc

.XtideUniversalBiosNotFound:
    pop     ds
    pop     es
    ret


;--------------------------------------------------------------------
; EEPROM_FindXtideUniversalBiosROMtoESDI
;   Parameters:
;       Nothing
;   Returns:
;       ES:DI:  EEPROM segment
;       CF:     Set if EEPROM was found
;               Cleared if EEPROM not found
;   Corrupts registers:
;       AX, BX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
EEPROM_FindXtideUniversalBiosROMtoESDI:
    push    si
    push    cx

    xor     di, di                  ; Zero DI (offset)
    mov     bx, 0C000h              ; First possible ROM segment
ALIGN JUMP_ALIGN
.SegmentLoop:
    mov     es, bx                  ; Possible ROM segment to ES
    call    Buffers_IsXtideUniversalBiosSignatureInESDI
    je      SHORT .RomFound
    add     bx, 200h                ; Increment by 8kB
    jnc     SHORT .SegmentLoop      ; Loop until segment overflows
    clc
    jmp     SHORT .ReturnWithoutUpdatingCF
ALIGN JUMP_ALIGN
.RomFound:
    stc
.ReturnWithoutUpdatingCF:
    pop     cx
    pop     si
    ret


;--------------------------------------------------------------------
; EEPROM_LoadFromRomToRamComparisonBuffer
;   Parameters:
;       Nothing
;   Returns:
;       Nothing
;   Corrupts registers:
;       BX, CX, SI, DI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
EEPROM_LoadFromRomToRamComparisonBuffer:
    push    es
    push    ds

    mov     ds, [cs:g_cfgVars+CFGVARS.wEepromSegment]
    xor     si, si
    call    Buffers_GetFlashComparisonBufferToESDI
    eMOVZX  bx, BYTE [cs:g_cfgVars+CFGVARS.bEepromType]
    mov     cx, [cs:bx+g_rgwEepromTypeToSizeInWords]
    cld
    rep movsw

    pop     ds
    pop     es
    ret