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UNTESTED: still experimenting

partial-rewrite
Ben Blazak 2013-12-23 19:13:53 -08:00
parent 6b9d6916b2
commit 55e96d5413
1 changed files with 35 additions and 28 deletions
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63
firmware/lib/layout/eeprom-macro/atmega32u4.c
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@ -21,10 +21,11 @@
* with the least significant byte occupying the lowest address. Protocols,
* data formats (including UTF-8), and such are primarily big endian. I like
* little endianness better -- it feels more mathematically consistent to me
* -- but after writing a bit of code, it seems that big endian
* serializations are slightly easier to work with, at least in C. For that
* reason, this code organizes bytes in a big endian manner whenever it has a
* choice between the two.
* -- but after writing a bit of code, it seems that while writing is easier
* to do as little endian, reading is easier to do as big endian; and since
* we'll be reading much more often than writing, big endian seems like the
* logical choice. For that reason, this code organizes bytes in a big
* endian manner whenever it has a choice between the two.
*
* - For a long time, I was going to try to make this library robust in the
* event of power loss, but in the end I decided not to. This feature is
@ -147,13 +148,13 @@ typedef struct {
// the file, as well as the documented order of the bytes for the stored
// start and end addresses of the EEPROM
//
// - sizes (in bytes):
// - sizes (in bytes) (with optimizations on):
//
// function frame stack
// read big 170 3 10
// read little 200 3 12
// write big 268 0 9
// write little 174 0 5
// function frame stack
// read big 154 3 10
// read little 200 3 12
// write big 208 0 9
// write little 172 0 5
/**
* TODO
@ -170,12 +171,17 @@ key_action_t read_key_action_big_endian(void * from) {
while (byte >> 7) {
byte = eeprom__read(from++);
k.layer = (k.layer << 2) | (byte >> 4 & 0b11);
k.row = (k.row << 2) | (byte >> 2 & 0b11);
k.column = (k.column << 2) | (byte >> 0 & 0b11);
k.layer <<= 2;
k.row <<= 2;
k.column <<= 2;
k.layer |= byte >> 4 & 0b11;
k.row |= byte >> 2 & 0b11;
k.column |= byte >> 0 & 0b11;
}
return k;
return k; // success
}
key_action_t read_key_action_little_endian(void * from) {
uint8_t byte = eeprom__read(from++);
@ -187,14 +193,14 @@ key_action_t read_key_action_little_endian(void * from) {
.column = byte >> 0 & 0b11,
};
for (uint8_t i=1; i<4 && byte>>7; i++) {
for (uint8_t i=2; i<8 && byte>>7; i+=2) {
byte = eeprom__read(from++);
k.layer |= ( byte >> 4 & 0b11 ) << i*2;
k.row |= ( byte >> 2 & 0b11 ) << i*2;
k.column |= ( byte >> 0 & 0b11 ) << i*2;
k.layer |= ( byte >> 4 & 0b11 ) << i;
k.row |= ( byte >> 2 & 0b11 ) << i;
k.column |= ( byte >> 0 & 0b11 ) << i;
}
return k;
return k; // success
}
/**
@ -204,23 +210,24 @@ uint8_t write_key_action_big_endian(void * to, key_action_t k) {
if (to > EEMEM_END-3)
return 1; // error: might not be enough space
int8_t i = 3;
int8_t i = 0;
uint8_t byte;
byte = k.layer | k.row | k.column;
for (; i>0 && !(byte >> i*2 & 0b11); i--);
while (byte >>= 2)
i += 2;
byte = (k.pressed ? 1 : 0) << 6;
for (; i>=0; i--) {
byte = byte | ( i>0 ? 1 : 0 ) << 7
| ( k.layer >> i*2 & 0b11 ) << 4
| ( k.row >> i*2 & 0b11 ) << 2
| ( k.column >> i*2 & 0b11 ) << 0 ;
for (; i>=0; i-=2) {
byte = byte | ( i>0 ? 1 : 0 ) << 7
| ( k.layer >> i & 0b11 ) << 4
| ( k.row >> i & 0b11 ) << 2
| ( k.column >> i & 0b11 ) << 0 ;
eeprom__write(to++, byte);
byte = 0;
}
return 0;
return 0; // success
}
uint8_t write_key_action_little_endian(void * to, key_action_t k) {
if (to > EEMEM_END-3)
@ -250,7 +257,7 @@ uint8_t write_key_action_little_endian(void * to, key_action_t k) {
eeprom__write(to, byte);
return 0;
return 0; // success
}
// TODO: rewriting (yet again) - stopped here