* peislam.asm - originally a PEI-slam helper, now hosts the GetTick
* and ReadBParam trampolines. The PEI-slam logic was rolled into
* iigsBlitStageToShr in joeyDraw.asm.

                keep    PEISLAM
                case    on


* Stub kept so the PEISLAM load segment stays present (the build's
* PORT_ASM_SRCS_ALL wildcard pulls in this file by name).
peislamStub     start   IIGSASM
                rtl
                end


****************************************************************
* uint16_t iigsGetTickWord(void)
*
* Calls Misc Toolset GetTick ($2503) and returns the low 16 bits of
* the 32-bit tick counter. The system increments this counter from
* the actual VBL hardware interrupt, so it stays accurate regardless
* of caller polling rate -- C-side polling of $C019 missed transitions
* for any op over ~1 ms.
*
* GetTick output convention: caller pushes 4 bytes of output space,
* tool dispatcher writes the LongWord into them. We pull the low 16
* bits into A (ORCA-C Word return convention -- A holds the result,
* not Y; verified against jIIgs.asm asmGetVbl) and discard the high
* 16 into X.
*
* ORCA-C cdecl ABI: caller has M=I=16. Word return in A.
****************************************************************

iigsGetTickWord start IIGSASM
                pha             ; output space high word
                pha             ; output space low word
                ldx     #$2503  ; _GetTick
                jsl     $E10000

                pla             ; A = low 16 bits (return value)
                plx             ; discard high 16 bits
                rtl
                end


****************************************************************
* uint16_t iigsReadHzParam(void)
*
* Reads battery RAM parameter hrtz50or60 ($1D) via _ReadBParam ($0C03)
* and returns the raw value: 0 = NTSC (60 Hz), 1 = PAL (50 Hz).
*
* GetTick fires from the hardware VBL ISR, so its rate matches the
* video field rate -- 60 Hz on NTSC, 50 Hz on PAL. halFrameHz must
* report whichever this machine actually runs so wall-clock math
* (frames * 1000 / halFrameHz) is correct on both.
****************************************************************

iigsReadHzParam start IIGSASM
                pha             ; output space (Word)
                pea     $001D   ; hrtz50or60 parameter ID
                ldx     #$0C03  ; _ReadBParam
                jsl     $E10000

                pla             ; A = result (ORCA-C Word return)
                rtl
                end