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Functions | |
| void | init_qtable_head_cache (void) |
| initialization of quantization tables (direct - JPEG header ones) cache TODO: add init_qtable_head_cache to module initialization | |
| int | get_qtable (int quality2, unsigned char *y_tab, unsigned char *c_tab) |
| calculates a pair of direct (JPEG header) tables for the specified quality (2-bytes ) | |
| void | init_qtable_fpga (void) |
| initialization of quantization tables (reverse, for the FPGA) cache TODO: add init_qtable_fpga to module initialization | |
| int | set_qtable_fpga (int quality2) |
| Finds an already programmed FPGA page or calculates (an programms FPGA with) a new one. | |
| void | reset_qtables (void) |
| force (re-)initilaization of quantization tables cache and FPGA qunatization table (in FPGA) when next used. | |
Definition in file quantization_tables.h.
| int get_qtable | ( | int | quality2, | |
| unsigned char * | y_tab, | |||
| unsigned char * | c_tab | |||
| ) |
calculates a pair of direct (JPEG header) tables for the specified quality (2-bytes )
| quality2 | single byte (standard) or a pair of bytes (see file header description) | |
| y_tab | caller-provided pointer to a 64-byte Y (intensity) quantization table (NULL - don't copy) | |
| c_tab | caller-provided pointer to a 64-byte C (color) quantization table (NULL - don't copy) |
look if such q value is already in cache
End of cache?
yes, re-use the LRE slot
no, hit or never used so far, and not the first - anyway use this slot
bypass this
this points to the old mre
this is now mre
is it a hit or a miss?
miss, calculate the table and save it to cache first
Safety limit on quality factor. Convert 0 to 1 to avoid zero divide.
The basic table is used as-is (scaling 100) for a quality of 50. Qualities 50..100 are converted to scaling percentage 200 - 2*Q; note that at Q=100 the scaling is 0, which will cause jpeg_add_quant_table to make all the table entries 1 (hence, minimum quantization loss). Qualities 1..50 are converted to scaling percentage 5000/Q.
limit the values to the valid range
now table pair is calculated and stored in cache
copy tables to the output
Definition at line 193 of file quantization_tables.c.
References D14, D1I, flags, init_qtable_head_cache(), local_irq_restore, local_irq_save, MDF14, MDF15, memcpy(), printk, qtable_cache, qtable_cache_initialized, qtable_cache_mre, qtable_cache_next, qtable_cache_values, QTABLE_HEAD_CACHE, QTABLE_SIZE, and std_quant_tbls.
Referenced by jpegheader_create(), and qtables_create().
| void init_qtable_fpga | ( | void | ) |
initialization of quantization tables (reverse, for the FPGA) cache
TODO: add init_qtable_fpga to module initialization
needs to turn off IRQ
Definition at line 288 of file quantization_tables.c.
References D1I, flags, FPGA_NQTAB, local_irq_restore, local_irq_save, MDF14, printk, qtable_fpga_initialized, qtable_fpga_mre, qtable_fpga_next, and qtable_fpga_values.
Referenced by set_qtable_fpga().
| void init_qtable_head_cache | ( | void | ) |
initialization of quantization tables (direct - JPEG header ones) cache
TODO: add init_qtable_head_cache to module initialization
needs to turn off IRQ
undefined
last value is invalid, but that's OK - it should not be used
Definition at line 171 of file quantization_tables.c.
References D1I, flags, local_irq_restore, local_irq_save, MDF, printk, qtable_cache_initialized, qtable_cache_mre, qtable_cache_next, qtable_cache_values, and QTABLE_HEAD_CACHE.
Referenced by get_qtable().
| void reset_qtables | ( | void | ) |
force (re-)initilaization of quantization tables cache and FPGA qunatization table (in FPGA) when next used.
Definition at line 161 of file quantization_tables.c.
References qtable_cache_initialized, and qtable_fpga_initialized.
Referenced by image_acq_init().
| int set_qtable_fpga | ( | int | quality2 | ) |
Finds an already programmed FPGA page or calculates (an programms FPGA with) a new one.
| quality2 | single byte (standard) or a pair of bytes (see file header description) |
look if such q value is already in cache
NOTE: never
End of cache?
yes, re-use the LRE slot
NOTE: never
no, hit or never used so far, and not the latest - anyway use this slot
bypass this
this points to the old mre
this is now mre
NOTE: never
is it a hit or miss?
miss, calculate the table and send it to the FPGA
Safety limit on quality factor. Convert 0 to 1 to avoid zero divide.
The basic table is used as-is (scaling 100) for a quality of 50. Qualities 50..100 are converted to scaling percentage 200 - 2*Q; note that at Q=100 the scaling is 0, which will cause jpeg_add_quant_table to make all the table entries 1 (hence, minimum quantization loss). Qualities 1..50 are converted to scaling percentage 5000/Q.
limit the values to the valid range
now table pair is calculated and stored in cache
copy tables to the FPGA
Definition at line 307 of file quantization_tables.c.
References CX313_FPGA_TABLES_QUANT, D14, D15, D1I, flags, FPGA_NQTAB, fpga_table_write_nice(), init_qtable_fpga(), local_irq_restore, local_irq_save, MDF14, MDF15, printk, qtable_fpga_initialized, qtable_fpga_mre, qtable_fpga_next, qtable_fpga_values, QTABLE_SIZE, and std_quant_tbls.
Referenced by pgm_quality().
1.5.1