add auto cpu frequency

When this feature enabled:
* Frequency sets to 14MHz on esxdos activity - for fastest loading from
sd card;
* Frequency sets to 14MHz on 48 BASIC startup;
* Frequency sets to 3.5MHz within ~1ms after #FE port access - this
allows to load from tape within turbo mode. Also this improves beeper
sound effects;
* Otherwise user configured frequency is used.

fpga/rtl/magic.sv

@@ -2,6 +2,7 @@ import common::*;
 module magic(
     input rst_n,
     input clk28,
+    input ck35,
 
     cpu_bus bus,
     output [7:0] d_out,
@@ -14,6 +15,7 @@ module magic(
     input magic_button,
     input pause_button,
     input div_paged,
+    input basic48_paged,
 
     output reg magic_mode,
     output reg magic_map,
@@ -74,13 +76,15 @@ end
 
 
 /* MAGIC CONFIG */
+turbo_t turbo0;
+reg autoturbo_en;
 wire config_cs = magic_map && bus.ioreq && bus.a[7:0] == 8'hFF;
 always @(posedge clk28 or negedge rst_n) begin
     if (!rst_n) begin
         magic_reboot <= 0;
         magic_beeper <= 0;
         machine <= MACHINE_PENT;
-        turbo <= TURBO_NONE;
+        turbo0 <= TURBO_NONE;
         panning <= PANNING_ABC;
         joy_sinclair <= 0;
         divmmc_en <= 0;
@@ -90,11 +94,12 @@ always @(posedge clk28 or negedge rst_n) begin
         covox_en <= 1'b1;
         soundrive_en <= 1'b1;
         sd_indication_en <= 1'b1;
+        autoturbo_en <= 1'b0;
     end
     else if (config_cs && bus.wr) case (bus.a[15:8])
         8'h01: {magic_reboot, magic_beeper} <= bus.d[1:0];
         8'h02: machine <= machine_t'(bus.d[2:0]);
-        8'h03: turbo <= turbo_t'(bus.d[2:0]);
+        8'h03: turbo0 <= turbo_t'(bus.d[2:0]);
         8'h04: panning <= panning_t'(bus.d[1:0]);
         8'h07: joy_sinclair <= bus.d[0];
         8'h08: ay_en <= bus.d[0];
@@ -102,6 +107,7 @@ always @(posedge clk28 or negedge rst_n) begin
         8'h0A: ulaplus_en <= bus.d[0];
         8'h0B: {soundrive_en, covox_en} <= bus.d[1:0];
         8'h0C: sd_indication_en <= bus.d[0];
+        8'h0E: autoturbo_en <= bus.d[0];
     endcase
 end
 
@@ -115,6 +121,39 @@ always @(posedge clk28 or negedge rst_n) begin
 end
 
 
+/* AUTOMATIC TURBO */
+reg [11:0] portfe_noturbo; // 1170uS
+always @(posedge clk28 or negedge rst_n) begin
+    if (!rst_n)
+        portfe_noturbo <= 0;
+    else if (bus.ioreq && !bus.a[0])
+        portfe_noturbo <= 1'b1;
+    else if (|portfe_noturbo && ck35)
+        portfe_noturbo <= portfe_noturbo + 1'b1;
+end
+reg basic48_ramclear_turbo;
+always @(posedge clk28 or negedge rst_n) begin
+    if (!rst_n)
+        basic48_ramclear_turbo <= 0;
+    else if (basic48_paged && bus.m1 && bus.a[15:6] == 10'b0001000111)
+        basic48_ramclear_turbo <= 1'b1;
+    else if (!basic48_paged || (bus.m1 && bus.a[15:6] != 10'b0001000111))
+        basic48_ramclear_turbo <= 0;
+end
+always @(posedge clk28 or negedge rst_n) begin
+    if (!rst_n)
+        turbo <= TURBO_NONE;
+    else if (autoturbo_en && div_paged && !magic_map)
+        turbo <= TURBO_14;
+    else if (autoturbo_en && |portfe_noturbo)
+        turbo <= TURBO_NONE;
+    else if (autoturbo_en && basic48_ramclear_turbo)
+        turbo <= TURBO_14;
+    else
+        turbo <= turbo0;
+end
+
+
 /* BUS CONTROLLER */
 assign d_out_active = config_rd;
 assign d_out = config_data;

fpga/rtl/top.sv

@@ -227,6 +227,7 @@ assign sd_indication = sd_indication_en & ~sd_cs;
 magic magic0(
     .rst_n(n_rstcpu),
     .clk28(clk28),
+    .ck35(ck35),
 
     .bus(bus),
     .d_out(magic_dout),
@@ -239,6 +240,7 @@ magic magic0(
     .magic_button(ps2_key_magic),
     .pause_button(ps2_key_pause),
     .div_paged(div_map && !div_mapram),
+    .basic48_paged(basic48_paged),
 
     .magic_mode(magic_mode),
     .magic_map(magic_map),

rom_src/config.asm

@@ -32,6 +32,8 @@ sd         DB 2
 ulaplus    DB 1
 dac        DB 3
 sdind      DB 1
+_reserv4   DB 0
+autoturbo  DB 0
     ENDS
 
 CFG_DEFAULT CFG_T

rom_src/menu_structure.asm

@@ -44,6 +44,7 @@ menudefault: MENU_DEF 20
 
 menuadv: MENU_DEF 22
     MENUENTRY_T str_sd_indication menu_sdind_value_cb     menu_sdind_cb
+    MENUENTRY_T str_autoturbo     menu_autoturbo_value_cb menu_autoturbo_cb
     MENUENTRY_T str_back          0                       menu_back_cb
     MENUENTRY_T 0
 .end:
@@ -130,6 +131,15 @@ menu_sdind_value_cb:
 .values_table:
     DW str_off_short.end-2
     DW str_on_short.end-2
+
+menu_autoturbo_value_cb:
+    ld ix, .values_table
+    ld a, (cfg.autoturbo)
+    jp menu_value_get
+.values_table:
+    DW str_off_short.end-2
+    DW str_on_short.end-2
+
 menu_value_get:
     sla a
     ld c, a
@@ -231,6 +241,15 @@ menu_sdind_cb:
     out (c), a
     ret
 
+menu_autoturbo_cb:
+    ld a, (cfg.autoturbo)
+    ld c, 1
+    call menu_handle_press
+    ld (cfg.autoturbo), a
+    ld bc, #0eff
+    out (c), a
+    ret
+
 menu_back_cb:
     call restore_screen
     ld hl, (var_menumain)

rom_src/strings.asm

@@ -41,4 +41,5 @@ str_dac_sd:            DEFSTR "      SD"
 str_dac_covoxsd:       DEFSTR "Covox+SD"
 str_menuadv:           DEFSTR "Advanced..."
 str_sd_indication:     DEFSTR "SD indication"
+str_autoturbo:         DEFSTR "Auto CPU freq"
 str_back:              DEFSTR "Go back..."