finished code to calculate number of blocks in CBDOS

src/dos_m65/utils/util_dir_filesize.s

@@ -7,13 +7,75 @@ util_dir_filesize_bytes: ; preserves .X
 	; Convert file size in bytes (32-bit value) to blocks, afterwards
 	; continue processing in 'util_dir_filesize_blocks'
 
-	; XXX temporary - calculate size in 254-byte blocks
-
-	lda PAR_FSIZE_BYTES+1
-	sta PAR_FSIZE_BLOCKS+0
+	; Start from handling some large values
+	
+	lda PAR_FSIZE_BYTES+3
+	+bne util_dir_filesize_max         ; file over 16MB size
 	lda PAR_FSIZE_BYTES+2
+	inc
+	+beq util_dir_filesize_max         ; file over 8MB size 
+
+	; Set initial size as 0 blocks
+	
+	lda #$00
+	sta PAR_FSIZE_BLOCKS+0
 	sta PAR_FSIZE_BLOCKS+1
 
+	; Calculate number of blocks
+
+	ldy #$03
+
+@lp:
+
+	lda PAR_FSIZE_BYTES+2
+	cmp util_dir_cmptab_hi,y
+	bcc @lp_next
+	bne @lp_adc_sbc
+	lda PAR_FSIZE_BYTES+1
+	cmp util_dir_cmptab_mi,y
+	bcc @lp_next
+	bne @lp_adc_sbc
+	lda PAR_FSIZE_BYTES+0
+	cmp util_dir_cmptab_lo,y
+	bcc @lp_next
+
+@lp_adc_sbc:
+
+	clc
+	lda PAR_FSIZE_BLOCKS+0
+	adc util_dir_addtab_lo,y
+	sta PAR_FSIZE_BLOCKS+0
+	lda PAR_FSIZE_BLOCKS+1
+	adc util_dir_addtab_hi,y
+	sta PAR_FSIZE_BLOCKS+1
+
+	sec
+	lda PAR_FSIZE_BYTES+0
+	sbc util_dir_cmptab_lo, y
+	sta PAR_FSIZE_BYTES+0
+	lda PAR_FSIZE_BYTES+1
+	sbc util_dir_cmptab_mi, y
+	sta PAR_FSIZE_BYTES+1
+	lda PAR_FSIZE_BYTES+2
+	sbc util_dir_cmptab_hi, y
+	sta PAR_FSIZE_BYTES+2
+
+	bra @lp
+
+@lp_next:
+
+	dey
+	bpl @lp
+	
+	; Correct for bytes not filling in the whole block
+	
+	lda PAR_FSIZE_BYTES+0
+	beq util_dir_filesize_blocks
+	
+	inc PAR_FSIZE_BLOCKS+0
+	bne util_dir_filesize_blocks
+	inc PAR_FSIZE_BLOCKS+1
+
 	; FALLTROUGH
 
 util_dir_filesize_blocks: ; preserves .X
@@ -95,3 +157,26 @@ util_dir_filesize_4: ; file size needs 4 digits
 
 	ldy #$00
 	rts
+
+
+; Tables for calculating blocks from bytes
+
+util_dir_addtab_hi:
+
+	!byte $00, $00 ; 2 next bytes same as in 'lo' table
+
+util_dir_addtab_lo:	
+
+	!byte $01, $10, $00, $00
+
+util_dir_cmptab_hi:
+
+	!byte ^(254), ^(254 * 16), ^(254 * 16 * 16), ^(254 * 16 * 16 * 16), ^(254 * 16 * 16 * 16 * 16)
+
+util_dir_cmptab_mi:
+
+	!byte >(254), >(254 * 16), >(254 * 16 * 16), >(254 * 16 * 16 * 16), >(254 * 16 * 16 * 16 * 16)
+
+util_dir_cmptab_lo:
+
+	!byte <(254), <(254 * 16), <(254 * 16 * 16), <(254 * 16 * 16 * 16), <(254 * 16 * 16 * 16 * 16)