Streaming PCM Audio from SD Card?

[Dacobi]

There's 16 bit multiplication in the new VERA

Is this in the FX update?

I'm not sure if this would be useful in my case. I'd need both add, sub, mul and div both signed and unsigned.

[Daedalus]

Adding and subtracting 16 bit values is pretty simple in assembly, I use macros for those.

Here are 16 bit add and subtract macros as examples

Code: Select all

.macro math_ADD_16_16 operand, result
	clc
	lda result
	adc operand
	sta result
	lda result+1
	adc operand+1
	sta result+1
	.endmacro
.

:
and:

Code: Select all

macro math_SUB_16_16 minuend, result
	sec
	lda result
	sbc minuend
	sta result
	lda result+1
	sbc minuend+1
	sta result+1
	.endmacro

Individually, they're pretty simple. They're great because they only use one line of assembly code to use, and once debugged, can be assured to work the same again and again.

Multiplication and division use WAY more instructions to implement, but are not complex. The algorithms are the same ones you learned in grade school to multiply and divide, except the "multiplication table" has only one entry instead of 100 for base 10 math.

I have a function that does the multiply, I've never needed to implement a divide. But what I do all the time, is multiple or divide by powers of two... When designing your systems, and they need math, ask yourself "Can I juke this such that it's power of 2 centric?" Because if you can, you can just use a shift algorithm to shift up or down to multiply or divide by a power of 2.

Here's the "shift down 16" macro:

Code: Select all

.macro math_SHIFT_DOWN_16 num_bits, addr16
	phx
	ldx num_bits
	beq :++	; Do nothing if 0 bits
	:
	clc
	lda addr16+1
	ror
	sta addr16+1
	lda addr16
	ror
	sta addr16
	dex
	bne :-
	:
	plx
	.endmacro

I put all of my math macros in a file called "math.inc", it's asm file, "math.asm" has the few routines I use for math.

[Daedalus]

Also, before you say "Send me your macros!" (Which I would gladly do.) Bear in mind that while I have decades of experience with C, I'm only been using the 65c02 in any serious capacity since last November, So I should not be considered an "expert."

[Dacobi]

Also, before you say "Send me your macros!" (Which I would gladly do.) Bear in mind that while I have decades of experience with C, I'm only been using the 65c02 in any serious capacity since last November, So I should not be considered an "expert."

I would love to take a look at your files and regarding the "expert" thing, I haven't done any real work in asm since 1994 in 16bit x86 asm in DOS, so in any case you'd be an expert compared to me : )