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Completely eliminates extra stack-allocated buffers

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This commit is contained in:
Roger Braunstein 2024-07-07 15:37:32 -07:00
parent 715e6427bb
commit a751f4f9a6
1 changed files with 27 additions and 26 deletions
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53
Cart_Reader/LYNX.ino
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@ -121,19 +121,17 @@ static bool detectBlockSize_LYNX() {
lynxUseAudin = false;
lynxBlockSize = 0;
int i;
uint8_t block[LYNX_BLOCKADDR];
for (i = 0; i < LYNX_BLOCKADDR; i++) {
block[i] = readByte_LYNX(i, 0);
}
// Somewhat arbitrary, however many bytes would be unlikely to be
// coincidentally mirrored
const size_t DETECT_BYTES = 128;
for (i = 0; i < LYNX_BLOCKADDR; i++) {
for (int i = 0; i < DETECT_BYTES; i++) {
// If any differences are detected when AUDIN=1,
// AUDIN is used to bankswitch
// meaning we also use the maximum block size
// (1024kb cart / 256 blocks = 4kb block bank switched between two
// lower/upper 2kb blocks)
if (block[i] != readByte_LYNX(i, 1)) {
if (readByte_LYNX(i, 0) != readByte_LYNX(i, 1)) {
lynxUseAudin = true;
lynxBlockSize = 2048;
return true;
@ -143,16 +141,14 @@ static bool detectBlockSize_LYNX() {
// Use the already-dumped 2KB to detect mirroring in a small sample
// Valid cart sizes of 128kb, 256kb, 512kb / 256 blocks
// = block sizes of 512b, 1024b, 2048b
const size_t DETECT_BYTES = 128;
for (i = 0; i < DETECT_BYTES; i++) {
if (block[i] != block[i + 256]) {
lynxBlockSize = max(lynxBlockSize, 512);
}
if (block[i] != block[i + 512]) {
lynxBlockSize = max(lynxBlockSize, 1024);
}
if (block[i] != block[i + 1024]) {
for (int i = 0; i < DETECT_BYTES; i++) {
uint8_t b = readByte_LYNX(i);
if (b != readByte_LYNX(i + 1024)) {
lynxBlockSize = max(lynxBlockSize, 2048);
} else if (b != readByte_LYNX(i + 512)) {
lynxBlockSize = max(lynxBlockSize, 1024);
} else if (b != readByte_LYNX(i + 256)) {
lynxBlockSize = max(lynxBlockSize, 512);
}
}
@ -197,16 +193,24 @@ static void writeHeader_LYNX() {
myFile.write(header, LYNX_HEADER_SIZE);
}
static void readROM_LYNX() {
uint8_t block[lynxBlockSize];
uint32_t i;
// Saves memory by using existing sd buffer instead of a second block-sized buffer (which could be up to 2KB)
// Minimum block size is 512b, size of sdBuffer is 512b, all block sizes multiples of 512b,
// so we shouldn't need to check for leftovers...
static inline void ringBufferWrite_LYNX(uint32_t blocki, uint8_t byte) {
sdBuffer[blocki % 512] = byte;
if ((blocki + 1) % 512 == 0) {
myFile.write(sdBuffer, 512);
}
}
static void readROM_LYNX() {
dataDir_LYNX(INPUT);
// The upper part of the address is used as a block address
// There are always 256 blocks, but the size of the block can vary
// So outer loop always steps through block addresses
uint32_t i;
const uint32_t upto = LYNX_BLOCKCOUNT * LYNX_BLOCKADDR;
for (uint32_t blockAddr = 0; blockAddr < upto; blockAddr += LYNX_BLOCKADDR) {
draw_progressbar(blockAddr, upto);
@ -215,26 +219,23 @@ static void readROM_LYNX() {
if (lynxUseAudin) {
// AUDIN bank switching uses a 4kb block split to 2 banks
for (i = 0; i < lynxBlockSize / 2; i++) {
block[i] = readByte_LYNX(blockAddr + i, 0);
ringBufferWrite_LYNX(i, readByte_LYNX(blockAddr + i, 0));
}
for (; i < lynxBlockSize; i++) {
block[i] = readByte_LYNX(blockAddr + i - (lynxBlockSize / 2), 1);
ringBufferWrite_LYNX(i, readByte_LYNX(blockAddr + i - (lynxBlockSize / 2), 1));
}
} else {
for (i = 0; i < lynxBlockSize; i++) {
block[i] = readByte_LYNX(i + blockAddr);
ringBufferWrite_LYNX(i, readByte_LYNX(i + blockAddr));
}
}
myFile.write(block, lynxBlockSize);
}
draw_progressbar(upto, upto);
}
#pragma region MENU
static const char* const menuOptionsLYNX[] PROGMEM = {FSTRING_READ_ROM,
FSTRING_RESET};
static const char* const menuOptionsLYNX[] PROGMEM = {FSTRING_READ_ROM, FSTRING_RESET};
void lynxMenu() {
size_t menuCount = sizeof(menuOptionsLYNX) / sizeof(menuOptionsLYNX[0]);