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Make pgm_read_byte() and pgm_read_word() again backwards compatible c… #3319

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Make pgm_read_byte() and pgm_read_word() again backwards compatible c… #3319

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41 changes: 18 additions & 23 deletions cores/esp8266/pgmspace.h
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Original file line number Diff line number Diff line change
Expand Up @@ -88,29 +88,24 @@ int vsnprintf_P(char *str, size_t strSize, PGM_P formatP, va_list ap) __attribut

#ifdef __ets__

#define pgm_read_with_offset(addr, res) \
asm("extui %0, %1, 0, 2\n" /* Extract offset within word (in bytes) */ \
"sub %1, %1, %0\n" /* Subtract offset from addr, yielding an aligned address */ \
"l32i.n %1, %1, 0x0\n" /* Load word from aligned address */ \
"slli %0, %0, 3\n" /* Mulitiply offset by 8, yielding an offset in bits */ \
"ssr %0\n" /* Prepare to shift by offset (in bits) */ \
"srl %0, %1\n" /* Shift right; now the requested byte is the first one */ \
:"=r"(res), "=r"(addr) \
:"1"(addr) \
:);

static inline uint8_t pgm_read_byte(const void* addr) {
register uint32_t res;
pgm_read_with_offset(addr, res);
return (uint8_t) res; /* This masks the lower byte from the returned word */
}

/* Although this says "word", it's actually 16 bit, i.e. half word on Xtensa */
static inline uint16_t pgm_read_word(const void* addr) {
register uint32_t res;
pgm_read_with_offset(addr, res);
return (uint16_t) res; /* This masks the lower half-word from the returned word */
}
#define pgm_read_abstract(addr, result_type) \
(__extension__({ \
PGM_P __local = (PGM_P)(addr); \
register uint32_t __res; \
asm volatile("extui %0, %1, 0, 2\n" /* Extract offset within word (in bytes) */\
"sub %1, %1, %0\n" /* Subtract offset from addr, yielding an aligned address */\
"_l32i %1, %1, 0x0\n" /* Load word from aligned address */\
"slli %0, %0, 3\n" /* Multiply offset by 8, yielding an offset in bits */\
"ssr %0\n" /* Prepare to shift by offset (in bits) */\
"srl %0, %1\n" /* Shift right; now the requested byte is the first one */\
:"=r"(__res), "=r"(__local) \
:"1"(__local) \
:); \
(result_type) __res; \
}))

#define pgm_read_byte(addr) pgm_read_abstract(addr, uint8_t)
#define pgm_read_word(addr) pgm_read_abstract(addr, uint16_t)

#else //__ets__
#define pgm_read_byte(addr) (*reinterpret_cast<const uint8_t*>(addr))
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