kolibrios-fun/programs/emulator/chip8/utils.inc

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; note: proc that defines without stdcall, call using "call"
; note: by stdcall convention callee is responsible for cleaning up the stack,
; arguments are pushed onto the stack in right-to-left order
align 4
proc _memset stdcall, dest:dword, val:byte, cnt:dword ; doesnt clobber any registers
;DEBUGF DBG_INFO, "memset(%x, %u, %u)\n", [dest], [val], [cnt]
push eax ecx edi
mov edi, dword [dest]
mov al, byte [val]
mov ecx, dword [cnt]
rep stosb
pop edi ecx eax
ret
endp
align 4
proc _srand stdcall, seed:dword
push eax
;DEBUGF DBG_INFO, "_srand: next_rand = %u\n", [next_rand]
mov eax, dword [seed]
mov dword [next_rand], eax
pop eax
ret
endp
align 4
proc _rand stdcall
push ebx edx
;DEBUGF DBG_INFO, "_rand: next_rand = %u\n", [next_rand]
mov eax, dword [next_rand]
mov ebx, 214013
mul ebx
add eax, 2531011
mov dword [next_rand], eax
shr eax, 16
and eax, 0x7fff
pop edx ebx
ret
endp
align 4
proc _getseed stdcall
push edx
rdtsc
xor eax, edx
pop edx
ret
endp
; calculate (num % num_mod) / num_div
align 4
proc mod_div stdcall, num: dword, num_mod: dword, num_div:dword ; TODO check
; in: num - number
; num_mod - first divisor
; num_div - second divisor
; out: eax - the result
; destroys: mb flags
push ecx edx
xor edx, edx
mov eax, dword [num]
mov ecx, dword [num_mod]
div ecx
mov eax, edx
xor edx, edx
mov ecx, dword [num_div]
div ecx
pop edx ecx
ret
endp
; update key map; TODO impl;
align 4
proc keyboard_update stdcall, _code: dword
push eax ebx ecx edx
mov eax, dword [_code]
mov edx, eax
and edx, 0xF000
mov ebx, eax
and ebx, 0x0F00
shr ebx, 8
xor ecx, ecx
cmp edx, 0x6000
jne .if1_end
mov ecx, 0x9
.if1_end:
add ebx, ecx
; DEBUGF DBG_INFO, "keynum %x\n", ebx
cmp ebx, KEY_SIZE
jae .ret
DEBUGF DBG_INFO, "keynum %x\n", ebx
mov byte [key + ebx], 1
.ret:
pop edx ecx ebx eax
ret
endp
; ; get seconds count
; align 4
; proc get_clock stdcall
; ; out: eax - time from system start in 10^-2 secs
; push ebx
; mov eax, 26
; mov ebx, 9
; int 0x40
; pop ebx
; ret
; endp