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comparison cpu_dsl.py @ 1710:2344b3650b38

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Fix sbc and implement carry/overflow flags for it in CPU DSL
author Michael Pavone <pavone@retrodev.com>
date Mon, 28 Jan 2019 22:56:43 -0800
parents 9c058ea77b7a
children 87d4f0b4bf1d
comparison
equal deleted inserted replaced
1709:9c058ea77b7a 1710:2344b3650b38
446 dst = params[2] 446 dst = params[2]
447 return decl + '\n\t{dst} = {a} + {b} + ({check} ? 1 : 0);'.format(dst = dst, 447 return decl + '\n\t{dst} = {a} + {b} + ({check} ? 1 : 0);'.format(dst = dst,
448 a = params[0], b = params[1], check = carryCheck 448 a = params[0], b = params[1], check = carryCheck
449 ) 449 )
450 450
451 def _sbcCImpl(prog, params, rawParams): 451 def _sbcCImpl(prog, params, rawParams, flagUpdates):
452 return '\n\t{dst} = {a} - {b} - ({check} ? 1 : 0);'.format(dst = params[2], 452 needsCarry = needsOflow = needsHalf = False
453 if flagUpdates:
454 for flag in flagUpdates:
455 calc = prog.flags.flagCalc[flag]
456 if calc == 'carry':
457 needsCarry = True
458 elif calc == 'half-carry':
459 needsHalf = True
460 elif calc == 'overflow':
461 needsOflow = True
462 decl = ''
463 carryCheck = _getCarryCheck(prog)
464 if needsCarry or needsOflow or needsHalf:
465 size = prog.paramSize(rawParams[2])
466 if needsCarry:
467 size *= 2
468 decl,name = prog.getTemp(size)
469 dst = prog.carryFlowDst = name
470 prog.lastA = params[1]
471 prog.lastB = '({b} ^ ({check} ? 1 : 0))'.format(b = params[0], check = carryCheck)
472 prog.lastBFlow = '((-{b}) ^ ({check} ? -1 : 0))'.format(b = params[0], check = carryCheck)
473 else:
474 dst = params[2]
475 return decl + '\n\t{dst} = {b} - {a} - ({check} ? 1 : 0);'.format(dst = dst,
453 a = params[0], b = params[1], check=_getCarryCheck(prog) 476 a = params[0], b = params[1], check=_getCarryCheck(prog)
454 ) 477 )
455 478
456 _opMap = { 479 _opMap = {
457 'mov': Op(lambda val: val).cUnaryOperator(''), 480 'mov': Op(lambda val: val).cUnaryOperator(''),