more sane directory name, updated binaries

src/kernal/tape/load_tape_normal.s

@@ -0,0 +1,172 @@
+// #LAYOUT# STD *        #TAKE
+// #LAYOUT# M65 KERNAL_1 #TAKE
+// #LAYOUT# *   *        #IGNORE
+
+//
+// Tape (normal) part of the LOAD routine
+//
+
+
+// We have the following possible CPU frequencies:
+// - C64    PAL:  CPU frequency 0.985248 MHz
+// - C64    NTSC: CPU frequency 1.022727 MHz
+// The clock difference is about 4% - it is unlikely to cause problems.
+//
+// We have to distinguish the following pulse lengths (http://sidpreservation.6581.org/tape-format/):
+// - S (short)    tap value $30 (PAL: 352 us)
+// - M (medium)   tap value $42 (PAL: 512 us)
+// - L (long)     tap value $56 (PAL: 672 us)
+//
+// The TAP format (http://unusedino.de/ec64/technical/formats/tap.html) uses a resolution of 8 PAL ticks;
+// this implementation sets the timer for twice the precision (timer B is triggered every 4 CPU cycles),
+// probably an overkill, but in realityy it does not cost us anything.
+//
+// So - we have the following thresholds:
+// - S vs M       $72 (in our units of 4 ticks)
+// - M vs L       $98 (in our units of 4 ticks)
+//
+// We need to recognize the following pulse sequences:
+//
+// (S,M) = 0 bit
+// (M,S) = 1 bit
+// (L,M) = new-data marker
+// (L,S) = end-of-data marker
+
+
+#if CONFIG_TAPE_NORMAL
+
+
+#if !CONFIG_TAPE_AUTODETECT
+
+load_tape_normal:
+
+	jsr tape_ditch_verify              // only LOAD is supported, no VERIFY
+
+	// Start playing
+	jsr tape_common_prepare_cia
+	jsr tape_ask_play
+#if CONFIG_TAPE_HEAD_ALIGN
+	jsr tape_prepare_reading
+#endif
+
+	// FALLTROUGH
+
+load_tape_normal_header:
+
+#else
+
+load_tape_normal_takeover:             // entry point for turbo->normal takeover
+
+#endif
+
+	jsr load_MEMUSS_to_STAL
+
+	// Try to load header into tape buffer (we will restore MEMUSS later)
+
+	jsr tape_normal_get_pilot_header
+#if CONFIG_TAPE_AUTODETECT
+	bcs load_tape_normal_switch_turbo  // failed, try turbo
+#endif
+
+	jsr load_TAPE1_to_MEMUSS
+	jsr tape_normal_get_data_1
+#if !CONFIG_TAPE_AUTODETECT
+	bcs load_tape_normal_header        // unable to read block, try again
+#else
+	bcc !+
+load_tape_normal_switch_turbo:
+	jsr lvs_STAL_to_MEMUSS
+	jmp load_tape_turbo_takeover       // unable to read block, try turbo instead
+!:
+#endif
+
+#if CONFIG_TAPE_NO_ERROR_CORRECTION
+	lda RIPRTY
+	cmp #$01                           // sets Carry if checksum verification fails
+#else
+	jsr load_TAPE1_to_MEMUSS
+	jsr tape_normal_get_data_2
+#endif
+#if !CONFIG_TAPE_AUTODETECT
+	bcs load_tape_normal_header        // block load error, try again
+#else
+	bcs load_tape_normal_switch_turbo  // block load error, try turbo instead
+#endif
+
+	// Check header type
+
+	ldy #$00
+	lda (TAPE1),y
+
+	cmp #$05
+	beq_16 tape_load_error             // end of tape mark, nothing to load
+
+	cmp #$01
+	beq !+
+	cmp #$03
+#if !CONFIG_TAPE_AUTODETECT
+	bne load_tape_normal_header        // header types 1 and 3 are loadable, see Mapping the C64, page 77
+#else
+	bne load_tape_normal_takeover
+#endif
+
+	lda #$01
+	sta SA                             // this file is non-relocatable; override secondary address with 1
+!:
+	// Restore MEMUSS, handle header
+
+	jsr lvs_STAL_to_MEMUSS
+	jsr tape_handle_header
+#if !CONFIG_TAPE_AUTODETECT
+	bcs load_tape_normal_header        // if name does not match, look for other header
+#else
+	bcs load_tape_normal_takeover
+#endif
+
+	// FALLTROUGH
+
+load_tape_normal_payload:
+
+	// Retrieve data
+
+	jsr tape_normal_get_pilot_data
+	ldy #$00                           // no data size limit
+	jsr tape_normal_get_data_1
+	bcs_16 tape_load_error
+
+	jsr lvs_check_EAL
+	bne_16 tape_load_error             // amount of data read does not match header info
+
+#if CONFIG_TAPE_NO_ERROR_CORRECTION
+	lda RIPRTY
+	cmp #$01                           // sets Carry if checksum verification fails
+#else
+	jsr lvs_STAL_to_MEMUSS
+	jsr tape_normal_get_data_2
+#endif
+	bcs_16 tape_load_error
+
+	jmp tape_load_success
+
+
+
+load_TAPE1_to_MEMUSS:                   // set MEMUSS (start address) as tape buffer 
+
+	lda TAPE1+1
+	sta MEMUSS+1
+	lda TAPE1+0
+	sta MEMUSS+0
+
+	rts
+
+load_MEMUSS_to_STAL:                   // preserve MEMUSS
+
+	lda MEMUSS+1
+	sta STAL+1
+	lda MEMUSS+0
+	sta STAL+0
+
+	rts
+
+
+#endif