int_fast32_t a, b; a = 1; /* the first two numbers of the sequence */ b = 1; /* * Compute two more numbers per iteration. * * An optimizing compiler might run this loop at compile * time, and store the answer within the object file. */ for (count = 4; count <= 40; count += 2) { a = a + b; b = a + b; }

## the first two numbers in the sequence li %r29, 1 li %r30, 1 ## compute two more numbers per iteration li %r0, (40 - 2) / 2 mtctr %r0 # number of loop iterations 5: add %r29, %r29, %r30 add %r30, %r29, %r30 bdnz 5b # loop ctr times

## Formula (suggested by gcc) to divide by 10, is to ## 0xcccccccd ## multiply by ----------- = 0.100000000005821 ## 0x800000000 ## which is to multiply by 0xcccccccd, then shift right 35. ## ... mulhwu %r9, %r5, %r4 # %r9 <= ((%r5 * %r4) >> 32) ... srwi %r9, %r9, 3 # %r9 <= (%r9 >> 3) mulli %r6, %r9, 10 sub %r6, %r5, %r6 # %r6 digit <= remainder

;; set stack pointer to #$1eff lda #$1eff txa ; this is so WRONG

lda #$1eec ; a9 ec 1e clc ; 18 adc #16 ; 69 10 00 sta cpio + $3dc.l ; 8f d0 03 70

;; nvmxdizc .define P_MSELECT %00100000 .define P_XSELECT %00010000 .define P_DECIMAL %00001000 sep #P_DECIMAL ; another MISTAKE rep #P_MSELECT | P_XSELECT

rep #P_MSELECT | P_XSELECT | P_DECIMAL

;; num1, num2 = 1 in decimal mode lda #1 sta <num1 sta <num2 stz <num1 + 2 stz <num2 + 2 stz <num1 + 4 stz <num2 + 4 ;; compute 40th Fibonacci number ldx #(40 - 2) / 2 ; number of loop iterations sed ; set decimal mode _fib_loop: ;; num1 = num1 + num2 lda <num1 clc adc <num2 sta <num1 lda <num1 + 2 adc <num2 + 2 ; carry sta <num1 + 2 lda <num1 + 4 adc <num2 + 4 ; carry sta <num1 + 4 ;; num2 = num1 + num2 lda <num2 clc adc <num1 sta <num2 lda <num2 + 2 adc <num1 + 2 ; carry sta <num2 + 2 lda <num2 + 4 adc <num1 + 4 ; carry sta <num2 + 4 dex bne _fib_loop ; loop X times cld ; clear decimal mode

;; Copy answer from format_buffer to cpio_pos. ;; ;; Attention! WLA-65816 reverses the operands of "mvn", which ;; moves a string of bytes from bank $ss to bank $dd: ;; mvn $ss, $dd ; standard syntax ;; mvn $dd, $ss ; wla-65816 syntax ;; ;; Our banks are ;; $ss == dp[format_buffer + 2] == answer >> 16 ;; $dd == dp[cpio_pos + 2] == cpio >> 16 ;; ldx <format_buffer ; x = source address ldy <cpio_pos ; y = destination address lda <format_bufsiz dec a ; a = length - 1 mvn cpio >> 16, answer >> 16

$ make find40th.sfc wla-65816 -o cpio-65816.s cpio-65816.o wla-65816 -o find40th-65816.s find40th-65816.o wla-65816 -o format-65816.s format-65816.o wlalink -r find40th-65816.link find40th.sfc $ snes9x-gtk find40th.sfc $ pax -rvf find40th.srm result pax: sv4crc vol 1, 1 files, 2048 bytes read, 0 bytes written. $ cat result 102334155 $

65xx => spc700 lda #$23 => mov a, #$23 sta $45 => mov $45, a tax => mov x, a pha lda $67 sta $89 => mov $89, $67 pla

65xx => spc700 clc clrc adc #$03 => adc a, #$03 pha lda $04 clc clrc adc $05 => adc $04, $05 sta $04 pla

65816 => spc700 rep #$20 lda $06 clc movw ya, $06 adc $08 => addw ya, $08 sta $06 movw $06, ya lda #$abcd => mov a, #$cd mov y, #$ab push x mov x, !$1357 mov $00, x mov x, !$1538 clc mov $01, x adc $1357 => addw ya, $00 pop x sta $0200 => mov !$0200, a mov !$0201, y

;; I want to use this code, ;; but the SPC-700 misses these addressing modes! ;; -- mov a, format_integer + y ; NO and a, #$0f ; yes mov x, a ; yes mov a, !digit_table + x ; yes mov x, !hex_low_placement + y ; NO mov [format_buffer] + x, a ; NO

;; This would be the code for the 65816. ;; -- lda.b format_integer, y ; NO, so use TYX and #$0f ; yes tax ; yes lda.w digit_table, x ; yes ldx.w hex_low_placement, y ; yes sta.b (format_buffer), x ; NO, so use PHY, TXY, PLY

;; This is the actual SPC-700 code in ;; 'hexformat' subroutine in my hack. ;; -- mov x, format_integer + y mov a, x ; a = byte from integer and a, #$0f mov x, a ; x = low digit mov a, !digit_table + x mov $00, a ; RAM $00 = ASCII digit mov a, !hex_low_placement + y push y mov y, a ; y = placement of digit mov a, $00 mov [format_buffer] + y, a ; place digit in buffer pop y ; restore y = loop counter