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Clean up architecture and some corrections
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,110 @@ | ||
| /////////////////////////////////////////////////////////////////////////////// | ||
| // Copyright Christopher Kormanyos 2024. | ||
| // Distributed under The Unlicense | ||
| // | ||
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| #include <stdbool.h> | ||
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| #include <startup/asm_util.h> | ||
| #include <mcal/mcal_gpt.h> | ||
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| // The clock is a 32-bit value that represents the number of seconds | ||
| // after midnight, January 1st, 1970. | ||
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| // The clock shadow is located at ports:41-44, where 41 is the least significant byte. | ||
| // The actual clock is located at ports:45-48, where 45 is the least significant byte. | ||
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| // See also: https://wikiti.brandonw.net/index.php?title=83Plus:Ports:40 | ||
| // See also: https://wikiti.brandonw.net/index.php?title=83Plus:Ports:41 | ||
| // See also: https://wikiti.brandonw.net/index.php?title=83Plus:Ports:45 | ||
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| static bool clock_seconds_run_bit_initial_state; | ||
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| static uint8_t clock_seconds_read_port40(void) ATTRIBUTE_NAKED; | ||
| static void clock_seconds_start (void) ATTRIBUTE_NAKED; | ||
| static void clock_seconds_stop (void) ATTRIBUTE_NAKED; | ||
| static uint8_t clock_seconds_value (void) ATTRIBUTE_NAKED; | ||
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| void mcal_gpt_init(void) | ||
| { | ||
| const uint8_t clock_seconds_run_bit_value = (uint8_t) (clock_seconds_read_port40() & (uint8_t) UINT8_C(1)); | ||
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| clock_seconds_run_bit_initial_state = ((clock_seconds_run_bit_value != (uint8_t) UINT8_C(0)) ? true : false); | ||
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| clock_seconds_start(); | ||
| } | ||
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| void mcal_gpt_de_init(void) | ||
| { | ||
| if(!clock_seconds_run_bit_initial_state) | ||
| { | ||
| clock_seconds_stop(); | ||
| } | ||
| } | ||
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| uint8_t mcal_gpt_get_time_elapsed(void) | ||
| { | ||
| return clock_seconds_value(); | ||
| } | ||
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| static uint8_t clock_seconds_read_port40(void) ATTRIBUTE_NAKED | ||
| { | ||
| __asm__("in a, (0x40)\n"); | ||
| __asm__("ld h, a\n"); | ||
| __asm__("ret\n"); | ||
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| #if defined(_MSC_VER) | ||
| return (uint8_t) UINT8_C(0); | ||
| #endif | ||
| } | ||
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| static void clock_seconds_start(void) ATTRIBUTE_NAKED | ||
| { | ||
| __asm__("in a, (0x48)\n"); // Read byte3 of the actual clock. | ||
| __asm__("out (0x44), a\n"); // Set byte3 of the clock shadow (using the value read above). | ||
| __asm__("in a, (0x47)\n"); // Read byte2 of the actual clock. | ||
| __asm__("out (0x43), a\n"); // Set byte2 of the clock shadow (using the value read above). | ||
| __asm__("in a, (0x46)\n"); // Read byte1 of the actual clock. | ||
| __asm__("out (0x42), a\n"); // Set byte1 of the clock shadow (using the value read above). | ||
| __asm__("xor a\n"); // Clear register a. | ||
| __asm__("out (0x41), a\n"); // Clear byte0 of the clock shadow. | ||
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| // Ensure that the set command bit is off since its transition | ||
| // to high will actually set the clock. The setting uses the values | ||
| // from the clock shadow at ports:45-48. | ||
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| __asm__("in a, (0x40)\n"); | ||
| __asm__("and a, #0xFC\n"); | ||
| __asm__("or a, #0x1\n"); | ||
| __asm__("out (0x40), a\n"); | ||
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| // Set and start the clock. | ||
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| __asm__("or a, #0x3\n"); | ||
| __asm__("out (0x40), a\n"); | ||
| __asm__("ret\n"); | ||
| } | ||
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| static void clock_seconds_stop(void) ATTRIBUTE_NAKED | ||
| { | ||
| // Stop the clock. | ||
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| __asm__("in a, (0x40)\n"); | ||
| __asm__("and a, #0xFE\n"); | ||
| __asm__("out (0x40), a\n"); | ||
| __asm__("ret\n"); | ||
| } | ||
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| static uint8_t clock_seconds_value(void) ATTRIBUTE_NAKED | ||
| { | ||
| // Return the lower 8-bits of the clock, where port:45 is | ||
| // the least significant byte of the clock. | ||
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| __asm__("in a, (0x45)\n"); | ||
| __asm__("ld h, a\n"); | ||
| __asm__("ret\n"); | ||
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| #if defined(_MSC_VER) | ||
| return (uint8_t) UINT8_C(0); | ||
| #endif | ||
| } |
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