| 1 | ; File name : CgaSnow.inc
|
|---|
| 2 | ; Project name : AssemblyLibrary
|
|---|
| 3 | ; Created date : 8.10.2010
|
|---|
| 4 | ; Last update : 8.10.2010
|
|---|
| 5 | ; Author : Tomi Tilli
|
|---|
| 6 | ; Description : Macros for preventing CGA snow.
|
|---|
| 7 | %ifndef CGASNOW_INC
|
|---|
| 8 | %define CGASNOW_INC
|
|---|
| 9 |
|
|---|
| 10 | ;--------------------------------------------------------------------
|
|---|
| 11 | ; WAIT_RETRACE_IF_NECESSARY_THEN
|
|---|
| 12 | ; Parameters:
|
|---|
| 13 | ; %1: Instruction that accessed CGA memory
|
|---|
| 14 | ; AL: Character to output
|
|---|
| 15 | ; AH: Attribute to output (stosw only)
|
|---|
| 16 | ; DS: BDA segment (zero)
|
|---|
| 17 | ; ES:SI: Ptr to video memory where to read from (if %1 reads)
|
|---|
| 18 | ; ES:DI: Ptr to video memory where to output (if %1 writes)
|
|---|
| 19 | ; Returns:
|
|---|
| 20 | ; SI, DI: Updated according to instruction
|
|---|
| 21 | ; Corrupts registers:
|
|---|
| 22 | ; AX, DX
|
|---|
| 23 | ;--------------------------------------------------------------------
|
|---|
| 24 | %macro WAIT_RETRACE_IF_NECESSARY_THEN 1
|
|---|
| 25 | %ifdef ELIMINATE_CGA_SNOW
|
|---|
| 26 | %ifidn %1, stosb
|
|---|
| 27 | call CgaSnow_Stosb
|
|---|
| 28 | %elifidn %1, stosw
|
|---|
| 29 | call CgaSnow_Stosw
|
|---|
| 30 | %elifidn %1, scasb
|
|---|
| 31 | call CgaSnow_Scasb
|
|---|
| 32 | %elifidn %1, rep movsb
|
|---|
| 33 | call CgaSnow_RepMovsb
|
|---|
| 34 | %else
|
|---|
| 35 | %error "Invalid instruction passed to WAIT_RETRACE_IF_NECESSARY_THEN"
|
|---|
| 36 | %endif
|
|---|
| 37 | %else ; No CGA snow prevention
|
|---|
| 38 | %ifidn %1, rep movsb
|
|---|
| 39 | eSEG_STR rep, es, movsb
|
|---|
| 40 | %else
|
|---|
| 41 | %1 ; Single instruction
|
|---|
| 42 | %endif
|
|---|
| 43 | %endif
|
|---|
| 44 | %endmacro
|
|---|
| 45 |
|
|---|
| 46 |
|
|---|
| 47 | ;--------------------------------------------------------------------
|
|---|
| 48 | ; WAIT_UNTIL_SAFE_CGA_WRITE
|
|---|
| 49 | ; Parameters:
|
|---|
| 50 | ; DX: CGA Status Register Address (3DAh)
|
|---|
| 51 | ; Returns:
|
|---|
| 52 | ; Nothing
|
|---|
| 53 | ; Corrupts registers:
|
|---|
| 54 | ; AL
|
|---|
| 55 | ;--------------------------------------------------------------------
|
|---|
| 56 | %macro WAIT_UNTIL_SAFE_CGA_WRITE 0
|
|---|
| 57 | %%WaitUntilNotInRetrace:
|
|---|
| 58 | in al, dx
|
|---|
| 59 | shr al, 1 ; 1 = Bit 0: A 1 indicates that regen-buffer memory access can be
|
|---|
| 60 | ; made without interfering with the display. (H or V retrace)
|
|---|
| 61 | jc SHORT %%WaitUntilNotInRetrace
|
|---|
| 62 | %%WaitUntilNextRetraceStarts:
|
|---|
| 63 | in al, dx
|
|---|
| 64 | shr al, 1
|
|---|
| 65 | jnc SHORT %%WaitUntilNextRetraceStarts
|
|---|
| 66 | %endmacro
|
|---|
| 67 |
|
|---|
| 68 |
|
|---|
| 69 | %endif ; CGASNOW_INC
|
|---|
