Subversion Repositories Spectranet

[/] [trunk/] [syslib/] [detect.asm] - Rev 490

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;The MIT License
;
;Copyright (c) 2011 Alistair Cree
;
;Permission is hereby granted, free of charge, to any person obtaining a copy
;of this software and associated documentation files (the "Software"), to deal
;in the Software without restriction, including without limitation the rights
;to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
;copies of the Software, and to permit persons to whom the Software is
;furnished to do so, subject to the following conditions:
;
;The above copyright notice and this permission notice shall be included in
;all copies or substantial portions of the Software.
;
;THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
;IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
;FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
;AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
;LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
;OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
;THE SOFTWARE.

.include        "spectranet.inc"

;detects the presence of spectranet by setting the border to cyan and reading
;from the spectranet control register. If the value is different we signal an
;error by setting the carry flag, else return with carry clear.
.text

.globl F_detect_spectranet
F_detect_spectranet:
        push bc
        ld bc,CTRLREG
        ld a,5  ;cyan
        ei
        halt
        out (0xFE),a
        in a,(c)
        and 0x07        ;mask off bits
        pop bc
        and a
        cp 5
        ret z
        scf     ;signal error - no spectranet
        ret

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